Appendix A to Part 63 - Test Methods
40:16.0.1.1.1.46.325.36.122 : Appendix A
Appendix A to Part 63 - Test Methods Method 301 - Field Validation
of Pollutant Measurement Methods From Various Waste Media Using
Method 301 1.0 What is the purpose of Method 301? 2.0 What approval
must I have to use Method 301? 3.0 What does Method 301 include?
4.0 How do I perform Method 301? Reference Materials 5.0 What
reference materials must I use? Sampling Procedures 6.0 What
sampling procedures must I use? 7.0 How do I ensure sample
stability? Determination of Bias and Precision 8.0 What are the
requirements for bias? 9.0 What are the requirements for precision?
10.0 What calculations must I perform for isotopic spiking? 11.0
What calculations must I perform for comparison with a validated
method? 12.0 What calculations must I perform for analyte spiking?
13.0 How do I conduct tests at similar sources? Optional
Requirements 14.0 How do I use and conduct ruggedness testing? 15.0
How do I determine the Limit of Detection for the candidate test
method? Other Requirements and Information 16.0 How do I apply for
approval to use a candidate test method? 17.0 How do I request a
waiver? 18.0 Where can I find additional information? 19.0 Tables.
Using Method 301 1.0 What is the purpose of Method 301?
Method 301 provides a set of procedures for the owner or
operator of an affected source to validate a candidate test method
as an alternative to a required test method based on established
precision and bias criteria. These validation procedures are
applicable under 40 CFR part 63 or 65 when a test method is
proposed as an alternative test method to meet an applicable
requirement or in the absence of a validated method. Additionally,
the validation procedures of Method 301 are appropriate for
demonstration of the suitability of alternative test methods under
40 CFR parts 59, 60, and 61. If, under 40 CFR part 63 or 60, you
choose to propose a validation method other than Method 301, you
must submit and obtain the Administrator's approval for the
candidate validation method.
2.0 What approval must I have to use Method 301?
If you want to use a candidate test method to meet requirements
in a subpart of 40 CFR part 59, 60, 61, 63, or 65, you must also
request approval to use the candidate test method according to the
procedures in Section 16 of this method and the appropriate section
of the part (§ 59.104, § 59.406, § 60.8(b), § 61.13(h)(1)(ii), §
63.7(f), or § 65.158(a)(2)(iii)). You must receive the
Administrator's written approval to use the candidate test method
before you use the candidate test method to meet the applicable
federal requirements. In some cases, the Administrator may decide
to waive the requirement to use Method 301 for a candidate test
method to be used to meet a requirement under 40 CFR part 59, 60,
61, 63, or 65 in absence of a validated test method. Section 17 of
this method describes the requirements for obtaining a waiver.
3.0 What does Method 301 include?
3.1 Procedures. Method 301 includes minimum procedures to
determine and document systematic error (bias) and random error
(precision) of measured concentrations from exhaust gases,
wastewater, sludge, and other media. Bias is established by
comparing the results of sampling and analysis against a reference
value. Bias may be adjusted on a source-specific basis using a
correction factor and data obtained during the validation test.
Precision may be determined using a paired sampling system or
quadruplicate sampling system for isotopic spiking. A quadruplicate
sampling system is required when establishing precision for analyte
spiking or when comparing a candidate test method to a validated
method. If such procedures have not been established and verified
for the candidate test method, Method 301 contains procedures for
ensuring sample stability by developing sample storage procedures
and limitations and then testing them. Method 301 also includes
procedures for ruggedness testing and determining detection limits.
The procedures for ruggedness testing and determining detection
limits are required for candidate test methods that are to be
applied to multiple sources and optional for candidate test methods
that are to be applied at a single source.
3.2 Definitions.
Affected source means an affected source as defined in
the relevant part and subpart under Title 40 (e.g., 40 CFR
parts 59, 60, 61, 63, and 65).
Candidate test method means the sampling and analytical
methodology selected for field validation using the procedures
described in Method 301. The candidate test method may be an
alternative test method under 40 CFR part 59, 60, 61, 63, or
65.
Paired sampling system means a sampling system capable of
obtaining two replicate samples that are collected as closely as
possible in sampling time and sampling location (collocated).
Quadruplicate sampling system means a sampling system
capable of obtaining four replicate samples (e.g., two pairs
of measured data, one pair from each method when comparing a
candidate test method against a validated test method, or analyte
spiking with two spiked and two unspiked samples) that are
collected as close as possible in sampling time and sampling
location.
Surrogate compound means a compound that serves as a
model for the target compound(s) being measured (i.e.,
similar chemical structure, properties, behavior). The surrogate
compound can be distinguished by the candidate test method from the
compounds being analyzed.
4.0 How do I perform Method 301?
First, you use a known concentration of an analyte or compare
the candidate test method against a validated test method to
determine the bias of the candidate test method. Then, you collect
multiple, collocated simultaneous samples to determine the
precision of the candidate test method. Additional procedures,
including validation testing over a broad range of concentrations
over an extended time period are used to expand the applicability
of a candidate test method to multiple sources. Sections 5.0
through 17.0 of this method describe the procedures in detail.
Reference Materials 5.0 What reference materials must I use?
You must use reference materials (a material or substance with
one or more properties that are sufficiently homogenous to the
analyte) that are traceable to a national standards body
(e.g., National Institute of Standards and Technology
(NIST)) at the level of the applicable emission limitation or
standard that the subpart in 40 CFR part 59, 60, 61, 63, or 65
requires. If you want to expand the applicable range of the
candidate test method, you must conduct additional test runs using
analyte concentrations higher and lower than the applicable
emission limitation or the anticipated level of the target analyte.
You must obtain information about your analyte according to the
procedures in Sections 5.1 through 5.4 of this method.
5.1 Exhaust Gas Test Concentration. You must obtain a
known concentration of each analyte from an independent source such
as a specialty gas manufacturer, specialty chemical company, or
chemical laboratory. You must also obtain the manufacturer's
certification of traceability, uncertainty, and stability for the
analyte concentration.
5.2 Tests for Other Waste Media. You must obtain the pure
liquid components of each analyte from an independent manufacturer.
The manufacturer must certify the purity, traceability,
uncertainty, and shelf life of the pure liquid components. You must
dilute the pure liquid components in the same type medium or matrix
as the waste from the affected source.
5.3 Surrogate Analytes. If you demonstrate to the
Administrator's satisfaction that a surrogate compound behaves as
the analyte does, then you may use surrogate compounds for highly
toxic or reactive compounds. A surrogate may be an isotope or
compound that contains a unique element (e.g., chlorine)
that is not present in the source or a derivation of the toxic or
reactive compound if the derivative formation is part of the
method's procedure. You may use laboratory experiments or
literature data to show behavioral acceptability.
5.4 Isotopically-Labeled Materials. Isotope mixtures may
contain the isotope and the natural analyte. The concentration of
the isotopically-labeled analyte must be more than five times the
concentration of the naturally-occurring analyte.
Sampling Procedures 6.0 What sampling procedures must I use?
You must determine bias and precision by comparison against a
validated test method using isotopic spiking or using analyte
spiking (or the equivalent). Isotopic spiking can only be used with
candidate test methods capable of measuring multiple isotopes
simultaneously such as test methods using mass spectrometry or
radiological procedures. You must collect samples according to the
requirements specified in Table 301-1 of this method. You must
perform the sampling according to the procedures in Sections 6.1
through 6.4 of this method.
6.1 Isotopic Spiking. Spike all 12 samples with
isotopically-labelled analyte at an analyte mass or concentration
level equivalent to the emission limitation or standard specified
in the applicable regulation. If there is no applicable emission
limitation or standard, spike the analyte at the expected level of
the samples. Follow the applicable spiking procedures in Section
6.3 of this method.
6.2 Analyte Spiking. In each quadruplicate set, spike
half of the samples (two out of the four samples) with the analyte
according to the applicable procedure in Section 6.3 of this
method. You should spike at an analyte mass or concentration level
equivalent to the emission limitation or standard specified in the
applicable regulation. If there is no applicable emission
limitation or standard, spike the analyte at the expected level of
the samples. Follow the applicable spiking procedures in Section
6.3 of this method.
6.3 Spiking Procedure.
6.3.1 Gaseous Analyte with Sorbent or Impinger Sampling
Train. Sample the analyte being spiked (in the laboratory or
preferably in the field) at a mass or concentration that is
approximately equivalent to the applicable emission limitation or
standard (or the expected sample concentration or mass where there
is no standard) for the time required by the candidate test method,
and then sample the stack gas stream for an equal amount of time.
The time for sampling both the analyte and stack gas stream should
be equal; however, you must adjust the sampling time to avoid
sorbent breakthrough. You may sample the stack gas and the gaseous
analyte at the same time. You must introduce the analyte as close
to the tip of the sampling probe as possible.
6.3.2 Gaseous Analyte with Sample Container (Bag or
Canister). Spike the sample containers after completion of each
test run with an analyte mass or concentration to yield a
concentration approximately equivalent to the applicable emission
limitation or standard (or the expected sample concentration or
mass where there is no standard). Thus, the final concentration of
the analyte in the sample container would be approximately equal to
the analyte concentration in the stack gas plus the equivalent of
the applicable emission standard (corrected for spike volume). The
volume amount of spiked gas must be less than 10 percent of the
sample volume of the container.
6.3.3 Liquid or Solid Analyte with Sorbent or Impinger
Trains. Spike the sampling trains with an amount approximately
equivalent to the mass or concentration in the applicable emission
limitation or standard (or the expected sample concentration or
mass where there is no standard) before sampling the stack gas. If
possible, do the spiking in the field. If it is not possible to do
the spiking in the field, you must spike the sampling trains in the
laboratory.
6.3.4 Liquid and Solid Analyte with Sample Container (Bag or
Canister). Spike the containers at the completion of each test
run with an analyte mass or concentration approximately equivalent
to the applicable emission limitation or standard in the subpart
(or the expected sample concentration or mass where there is no
standard).
6.4 Probe Placement and Arrangement for Stationary Source
Stack or Duct Sampling. To sample a stationary source, you must
place the paired or quadruplicate probes according to the
procedures in this subsection. You must place the probe tips in the
same horizontal plane. Section 17.1 of Method 301 describes
conditions for waivers. For example, the Administrator may approve
a validation request where other paired arrangements for the probe
tips or pitot tubes (where required) are used.
6.4.1 Paired Sampling Probes. For paired sampling probes,
the first probe tip should be 2.5 centimeters (cm) from the outside
edge of the second probe tip, with a pitot tube on the outside of
each probe.
6.4.2 Quadruplicate Sampling Probes. For quadruplicate
sampling probes, the tips should be in a 6.0 cm × 6.0 cm square
area measured from the center line of the opening of the probe tip
with a single pitot tube, where required, in the center of the
probe tips or two pitot tubes, where required, with their location
on either side of the probe tip configuration. Section 17.1 of
Method 301 describes conditions for waivers. For example, you must
propose an alternative arrangement whenever the cross-sectional
area of the probe tip configuration is approximately five percent
or more of the stack or duct cross-sectional area.
7.0 How do I ensure sample stability?
7.1 Developing Sample Storage and Threshold Procedures.
If the candidate test method includes well-established procedures
supported by experimental data for sample storage and the time
within which the collected samples must be analyzed, you must store
the samples according to the procedures in the candidate test
method and you are not required to conduct the procedures specified
in Section 7.2 or 7.3 of this method. If the candidate test method
does not include such procedures, your candidate method must
include procedures for storing and analyzing samples to ensure
sample stability. At a minimum, your proposed procedures must meet
the requirements in Section 7.2 or 7.3 of this method. The minimum
duration between sample collection and storage must be as soon as
possible, but no longer than 72 hours after collection of the
sample. The maximum storage duration must not be longer than 2
weeks.
7.2 Storage and Sampling Procedures for Stack Test
Emissions. You must store and analyze samples of stack test
emissions according to Table 301-2 of this method. You may
reanalyze the same sample at both the minimum and maximum storage
durations for: (1) Samples collected in containers such as bags or
canisters that are not subject to dilution or other preparation
steps, or (2) impinger samples not subjected to preparation steps
that would affect stability of the sample such as extraction or
digestion. For candidate test method samples that do not meet
either of these criteria, you must analyze one of a pair of
replicate samples at the minimum storage duration and the other
replicate at the proposed storage duration but no later than 2
weeks of the initial analysis to identify the effect of storage
duration on analyte samples. If you are using the isotopic spiking
procedure, then you must analyze each sample for the spiked analyte
and the native analyte.
7.3 Storage and Sampling Procedures for Testing Other Waste
Media (e.g., Soil/Sediment, Solid Waste, Water/Liquid). You
must analyze one of each pair of replicate samples (half the total
samples) at the minimum storage duration and the other replicate
(other half of samples) at the maximum storage duration or within 2
weeks of the initial analysis to identify the effect of storage
duration on analyte samples. The minimum time period between
collection and storage should be as soon as possible, but no longer
than 72 hours after collection of the sample.
7.4 Sample Stability. After you have conducted sampling
and analysis according to Section 7.2 or 7.3 of this method,
compare the results at the minimum and maximum storage durations.
Calculate the difference in the results using Equation 301-1.

Where: di
= Difference between the results of the i th replicate pair of
samples. Rmini = Results from the i th replicate sample pair at the
minimum storage duration. Rmaxi = Results from the i th replicate
sample pair at the maximum storage duration.
For single samples that can be reanalyzed for sample stability
assessment (e.g., bag or canister samples and impinger
samples that do not require digestion or extraction), the values
for Rmini and Rmaxi will be obtained from the same sample rather
than replicate samples.
7.4.1 Standard Deviation. Determine the standard
deviation of the paired samples using Equation 301-2.

Where:
SDd = Standard deviation of the differences of the paired samples.
di = Difference between the results of the i th replicate pair of
samples. dm = Mean of the paired sample differences. n = Total
number of paired samples.
7.4.2 T Test. Test the difference in the results for
statistical significance by calculating the t-statistic and
determining if the mean of the differences between the results at
the minimum storage duration and the results after the maximum
storage duration is significant at the 95 percent confidence level
and n-1 degrees of freedom. Calculate the value of the t-statistic
using Equation 301-3.

Where:
t = t-statistic. dm = The mean of the paired sample
differences. SDd = Standard deviation of the differences of the
paired samples. n = Total number of paired samples.
Compare the calculated t-statistic with the critical value of
the t-statistic from Table 301-3 of this method. If the calculated
t-value is less than the critical value, the difference is not
statistically significant. Therefore, the sampling, analysis, and
sample storage procedures ensure stability, and you may submit a
request for validation of the candidate test method. If the
calculated t-value is greater than the critical value, the
difference is statistically significant, and you must repeat the
procedures in Section 7.2 or 7.3 of this method with new samples
using a shorter proposed maximum storage duration or improved
handling and storage procedures.
Determination of Bias and Precision 8.0 What are the requirements
for bias?
You must determine bias by comparing the results of sampling and
analysis using the candidate test method against a reference value.
The bias must be no more than ±10 percent for the candidate test
method to be considered for application to multiple sources. A
candidate test method with a bias greater than ±10 percent and less
than or equal to ±30 percent can only be applied on a
source-specific basis at the facility at which the validation
testing was conducted. In this case, you must use a correction
factor for all data collected in the future using the candidate
test method. If the bias is more than ±30 percent, the candidate
test method is unacceptable.
9.0 What are the requirements for precision?
You may use a paired sampling system or a quadruplicate sampling
system to establish precision for isotopic spiking. You must use a
quadruplicate sampling system to establish precision for analyte
spiking or when comparing a candidate test method to a validated
method. If you are using analyte spiking or isotopic spiking, the
precision, expressed as the relative standard deviation (RSD) of
the candidate test method, must be less than or equal to 20
percent. If you are comparing the candidate test method to a
validated test method, the candidate test method must be at least
as precise as the validated method as determined by an F test (see
Section 11.2.2 of this method).
10.0 What calculations must I perform for isotopic spiking?
You must analyze the bias, RSD, precision, and data acceptance
for isotopic spiking tests according to the provisions in Sections
10.1 through 10.4 of this method.
10.1 Numerical Bias. Calculate the numerical value of the
bias using the results from the analysis of the isotopic spike in
the field samples and the calculated value of the spike according
to Equation 301-4.

Where: B
= Bias at the spike level. Sm = Mean of the measured values of the
isotopically-labeled analyte in the samples. CS = Calculated value
of the isotopically-labeled spike level.
10.2 Standard Deviation. Calculate the standard deviation
of the Si values according to Equation 301-5.

Where: SD
= Standard deviation of the candidate test method. Si = Measured
value of the isotopically-labeled analyte in the i th field sample.
Sm = Mean of the measured values of the isotopically-labeled
analyte in the samples. n = Number of isotopically-spiked samples.
10.3 T Test. Test the bias for statistical significance
by calculating the t-statistic using Equation 301-6. Use the
standard deviation determined in Section 10.2 of this method and
the numerical bias determined in Section 10.1 of this method.

Where: t
= Calculated t-statistic. B = Bias at the spike level. SD =
Standard deviation of the candidate test method. n = Number of
isotopically spike samples.
Compare the calculated t-value with the critical value of the
two-sided t-distribution at the 95 percent confidence level and n-1
degrees of freedom (see Table 301-3 of this method). When you
conduct isotopic spiking according to the procedures specified in
Sections 6.1 and 6.3 of this method as required, this critical
value is 2.201 for 11 degrees of freedom. If the calculated t-value
is less than or equal to the critical value, the bias is not
statistically significant, and the bias of the candidate test
method is acceptable. If the calculated t-value is greater than the
critical value, the bias is statistically significant, and you must
evaluate the relative magnitude of the bias using Equation
301-7.

Where: BR
= Relative bias. B = Bias at the spike level. CS = Calculated value
of the spike level.
If the relative bias is less than or equal to 10 percent, the
bias of the candidate test method is acceptable for use at multiple
sources. If the relative bias is greater than 10 percent but less
than or equal to 30 percent, and if you correct all data collected
with the candidate test method in the future for bias using the
source-specific correction factor determined in Equation 301-8, the
candidate test method is acceptable only for application to the
source at which the validation testing was conducted and may not be
applied to any other sites. If either of the preceding two cases
applies, you may continue to evaluate the candidate test method by
calculating its precision. If not, the candidate test method does
not meet the requirements of Method 301.

Where: CF
= Source-specific bias correction factor. B = Bias at the spike
level. CS = Calculated value of the spike level.
If the CF is outside the range of 0.70 to 1.30, the data and
method are considered unacceptable.
10.4 Precision. Calculate the RSD according to Equation
301-9.

Where:
RSD = Relative standard deviation of the candidate test method. SD
= Standard deviation of the candidate test method calculated in
Equation 301-5. Sm = Mean of the measured values of the spike
samples.
The data and candidate test method are unacceptable if the RSD
is greater than 20 percent.
11.0 What calculations must I perform for comparison with a
validated method?
If you are comparing a candidate test method to a validated
method, then you must analyze the data according to the provisions
in this section. If the data from the candidate test method fail
either the bias or precision test, the data and the candidate test
method are unacceptable. If the Administrator determines that the
affected source has highly variable emission rates, the
Administrator may require additional precision checks.
11.1 Bias Analysis. Test the bias for statistical
significance at the 95 percent confidence level by calculating the
t-statistic.
11.1.1 Bias. Determine the bias, which is defined as the
mean of the differences between the candidate test method and the
validated method (dm). Calculate di according to Equation
301-10.

Where: di
= Difference in measured value between the candidate test method
and the validated method for each quadruplicate sampling train. V1i
= First measured value with the validated method in the ith
quadruplicate sampling train. V2i = Second measured value with the
validated method in the ith quadruplicate sampling train. P1i =
First measured value with the candidate test method in the ith
quadruplicate sampling train. P2i = Second measured value with the
candidate test method in the ith quadruplicate sampling train.
Calculate the numerical value of the bias using Equation
301-11.

Where: B
= Numerical bias. di = Difference between the candidate test method
and the validated method for the ith quadruplicate sampling train.
n = Number of quadruplicate sampling trains.
11.1.2 Standard Deviation of the Differences. Calculate
the standard deviation of the differences, SDd, using Equation
301-12.

Where:
SDd = Standard deviation of the differences between the candidate
test method and the validated method. di = Difference in measured
value between the candidate test method and the validated method
for each quadruplicate sampling train. dm = Mean of the
differences, di, between the candidate test method and the
validated method. n = Number of quadruplicate sampling trains.
11.1.3 T Test. Calculate the t-statistic using Equation
301-13.

Where:
t = Calculated t-statistic. dm = The mean of the
differences, di, between the candidate test method and the
validated method. SDd = Standard deviation of the differences
between the candidate test method and the validated method. n =
Number of quadruplicate sampling trains.
For the procedure comparing a candidate test method to a
validated test method listed in Table 301-1 of this method, n
equals six. Compare the calculated t-statistic with the critical
value of the t-statistic, and determine if the bias is significant
at the 95 percent confidence level (see Table 301-3 of this
method). When six runs are conducted, as specified in Table 301-1
of this method, the critical value of the t-statistic is 2.571 for
five degrees of freedom. If the calculated t-value is less than or
equal to the critical value, the bias is not statistically
significant and the data are acceptable. If the calculated t-value
is greater than the critical value, the bias is statistically
significant, and you must evaluate the magnitude of the relative
bias using Equation 301-14.

Where: BR
= Relative bias. B = Bias as calculated in Equation 301-11. VS =
Mean of measured values from the validated method.
If the relative bias is less than or equal to 10 percent, the
bias of the candidate test method is acceptable. On a
source-specific basis, if the relative bias is greater than 10
percent but less than or equal to 30 percent, and if you correct
all data collected in the future with the candidate test method for
the bias using the correction factor, CF, determined in Equation
301-8 (using VS for CS), the bias of the candidate test method is
acceptable for application to the source at which the validation
testing was conducted. If either of the preceding two cases
applies, you may continue to evaluate the candidate test method by
calculating its precision. If not, the candidate test method does
not meet the requirements of Method 301.
11.2 Precision. Compare the estimated variance (or
standard deviation) of the candidate test method to that of the
validated test method according to Sections 11.2.1 and 11.2.2 of
this method. If a significant difference is determined using the F
test, the candidate test method and the results are rejected. If
the F test does not show a significant difference, then the
candidate test method has acceptable precision.
11.2.1 Candidate Test Method Variance. Calculate the
estimated variance of the candidate test method according to
Equation 301-15.

Where: p
= Estimated variance of the candidate test method. di = The
difference between the i th pair of samples collected with the
candidate test method in a single quadruplicate train. n = Total
number of paired samples (quadruplicate trains).
Calculate the estimated variance of the validated test method
according to Equation 301-16.

Where: v
= Estimated variance of the validated test method. di = The
difference between the i th pair of samples collected with the
validated test method in a single quadruplicate train. n = Total
number of paired samples (quadruplicate trains).
11.2.2 The F test. Determine if the estimated variance of
the candidate test method is greater than that of the validated
method by calculating the F-value using Equation 301-17.

Where: F
= Calculated F value. p = The estimated variance of the candidate
test method. v = The estimated variance of the validated method.
Compare the calculated F value with the one-sided confidence
level for F from Table 301-4 of this method. The upper one-sided
confidence level of 95 percent for F(6,6) is 4.28 when the
procedure specified in Table 301-1 of this method for quadruplicate
sampling trains is followed. If the calculated F value is greater
than the critical F value, the difference in precision is
significant, and the data and the candidate test method are
unacceptable.
12.0 What calculations must I perform for analyte spiking?
You must analyze the data for analyte spike testing according to
this section.
12.1 Bias Analysis. Test the bias for statistical
significance at the 95 percent confidence level by calculating the
t-statistic.
12.1.1 Bias. Determine the bias, which is defined as the
mean of the differences between the spiked samples and the unspiked
samples in each quadruplicate sampling train minus the spiked
amount, using Equation 301-18.

Where: di
= Difference between the spiked samples and unspiked samples in
each quadruplicate sampling train minus the spiked amount. S1i =
Measured value of the first spiked sample in the i th quadruplicate
sampling train. S2i = Measured value of the second spiked sample in
the i th quadruplicate sampling train. M1i = Measured value of the
first unspiked sample in the i th quadruplicate sampling train. M2i
= Measured value of the second unspiked sample in the i th
quadruplicate sampling train. CS = Calculated value of the spike
level.
Calculate the numerical value of the bias using Equation
301-19.

Where: B
= Numerical value of the bias. di = Difference between the spiked
samples and unspiked samples in each quadruplicate sampling train
minus the spiked amount. n = Number of quadruplicate sampling
trains.
12.1.2 Standard Deviation of the Differences. Calculate
the standard deviation of the differences using Equation
301-20.

Where:
SDd = Standard deviation of the differences of paired samples. di =
Difference between the spiked samples and unspiked samples in each
quadruplicate sampling train minus the spiked amount. dm = The mean
of the differences, di, between the spiked samples and unspiked
samples. n = Total number of quadruplicate sampling trains.
12.1.3 T Test. Calculate the t-statistic using Equation
301-21, where n is the total number of test sample differences
(di). For the quadruplicate sampling system procedure in Table
301-1 of this method, n equals six.

Where: t
= Calculated t-statistic.
dm = Mean of the difference, di,
between the spiked samples and unspiked samples. SDd = Standard
deviation of the differences of paired samples. n = Number of
quadruplicate sampling trains.
Compare the calculated t-statistic with the critical value of
the t-statistic, and determine if the bias is significant at the 95
percent confidence level. When six quadruplicate runs are
conducted, as specified in Table 301-1 of this method, the 2-sided
confidence level critical value is 2.571 for the five degrees of
freedom. If the calculated t-value is less than the critical value,
the bias is not statistically significant and the data are
acceptable. If the calculated t-value is greater than the critical
value, the bias is statistically significant and you must evaluate
the magnitude of the relative bias using Equation 301-22.

Where: BR
= Relative bias. B = Bias at the spike level from Equation 301-19.
CS = Calculated value at the spike level.
If the relative bias is less than or equal to 10 percent, the
bias of the candidate test method is acceptable. On a
source-specific basis, if the relative bias is greater than 10
percent but less than or equal to 30 percent, and if you correct
all data collected with the candidate test method in the future for
the magnitude of the bias using Equation 301-8, the bias of the
candidate test method is acceptable for application to the tested
source at which the validation testing was conducted. Proceed to
evaluate precision of the candidate test method.
12.2 Precision. Calculate the standard deviation using
Equation 301-23.

Where: SD
= Standard deviation of the candidate test method. Si = Measured
value of the analyte in the i th spiked sample. Sm = Mean of the
measured values of the analyte in all the spiked samples. n =
Number of spiked samples.
Calculate the RSD of the candidate test method using Equation
301-9, where SD and Sm are the values from Equation 301-23. The
data and candidate test method are unacceptable if the RSD is
greater than 20 percent.
13.0 How do I conduct tests at similar sources?
If the Administrator has approved the use of an alternative test
method to a test method required in 40 CFR part 59, 60, 61, 63, or
65 for an affected source, and you would like to apply the
alternative test method to a similar source, then you must petition
the Administrator as described in Section 17.1.1 of this
method.
Optional Requirements 14.0 How do I use and conduct ruggedness
testing?
Ruggedness testing is an optional requirement for validation of
a candidate test method that is intended for the source where the
validation testing was conducted. Ruggedness testing is required
for validation of a candidate test method intended to be used at
multiple sources. If you want to use a validated test method at a
concentration that is different from the concentration in the
applicable emission limitation under 40 CFR part 59, 60, 61, 63, or
65, or for a source category that is different from the source
category that the test method specifies, then you must conduct
ruggedness testing according to the procedures in Reference 18.16
of Section 18.0 of this method and submit a request for a waiver
for conducting Method 301 at that different source category
according to Section 17.1.1 of this method.
Ruggedness testing is a study that can be conducted in the
laboratory or the field to determine the sensitivity of a method to
parameters such as analyte concentration, sample collection rate,
interferent concentration, collection medium temperature, and
sample recovery temperature. You conduct ruggedness testing by
changing several variables simultaneously instead of changing one
variable at a time. For example, you can determine the effect of
seven variables in only eight experiments. (W.J. Youden,
Statistical Manual of the Association of Official Analytical
Chemists, Association of Official Analytical Chemists, Washington,
DC, 1975, pp. 33-36).
15.0 How do I determine the Limit of Detection for the candidate
test method?
Determination of the Limit of Detection (LOD) as specified in
Sections 15.1 and 15.2 of this method is required for
source-specific method validation and validation of a candidate
test method intended to be used for multiple sources.
15.1 Limit of Detection. The LOD is the minimum
concentration of a substance that can be measured and reported with
99 percent confidence that the analyte concentration is greater
than zero. For this protocol, the LOD is defined as three times the
standard deviation, So, at the blank level.
15.2 Purpose. The LOD establishes the lower detection
limit of the candidate test method. You must calculate the LOD
using the applicable procedures found in Table 301-5 of this
method. For candidate test methods that collect the analyte in a
sample matrix prior to an analytical measurement, you must
determine the LOD using Procedure I in Table 301-5 of this method
by calculating a method detection limit (MDL) as described in 40
CFR part 136, appendix B. For the purposes of this section, the LOD
is equivalent to the calculated MDL. For radiochemical methods, use
the Multi-Agency Radiological Laboratory Analytical Protocols
(MARLAP) Manual (i.e., use the minimum detectable
concentration (MDC) and not the LOD) available at
https://www.epa.gov/radiation/marlap-manual-and-supporting-documents.
Other Requirements and Information 16.0 How do I apply for approval
to use a candidate test method?
16.1 Submitting Requests. You must request to use a
candidate test method according to the procedures in § 63.7(f) or
similar sections of 40 CFR parts 59, 60, 61, and 65 (§ 59.104, §
59.406, § 60.8(b), § 61.13(h)(1)(ii), or § 65.158(a)(2)(iii)). You
cannot use a candidate test method to meet any requirement under
these parts until the Administrator has approved your request. The
request must include a field validation report containing the
information in Section 16.2 of this method. You must submit the
request to the Group Leader, Measurement Technology Group, U.S.
Environmental Protection Agency, E143-02, Research Triangle Park,
NC 27711.
16.2 Field Validation Report. The field validation report
must contain the information in Sections 16.2.1 through 16.2.8 of
this method.
16.2.1 Regulatory objectives for the testing, including a
description of the reasons for the test, applicable emission
limits, and a description of the source.
16.2.2 Summary of the results and calculations shown in
Sections 6.0 through 16.0 of this method, as applicable.
16.2.3 Reference material certification and value(s).
16.2.4 Discussion of laboratory evaluations.
16.2.5 Discussion of field sampling.
16.2.6 Discussion of sample preparation and analysis.
16.2.7 Storage times of samples (and extracts, if
applicable).
16.2.8 Reasons for eliminating any results.
17.0 How do I request a waiver?
17.1 Conditions for Waivers. If you meet one of the
criteria in Section 17.1.1 or 17.1.2 of this method, the
Administrator may waive the requirement to use the procedures in
this method to validate an alternative or other candidate test
method. In addition, if the EPA currently recognizes an appropriate
test method or considers the candidate test method to be
satisfactory for a particular source, the Administrator may waive
the use of this protocol or may specify a less rigorous validation
procedure.
17.1.1 Similar Sources. If the alternative or other
candidate test method that you want to use was validated for
source-specific application at another source and you can
demonstrate to the Administrator's satisfaction that your affected
source is similar to that validated source, then the Administrator
may waive the requirement for you to validate the alternative or
other candidate test method. One procedure you may use to
demonstrate the applicability of the method to your affected source
is to conduct a ruggedness test as described in Section 14.0 of
this method.
17.1.2 Documented Methods. If the bias, precision, LOD,
or ruggedness of the alternative or other candidate test method
that you are proposing have been demonstrated through laboratory
tests or protocols different from this method, and you can
demonstrate to the Administrator's satisfaction that the bias,
precision, LOD, or ruggedness apply to your application, then the
Administrator may waive the requirement to use this method or to
use part of this method.
17.2 Submitting Applications for Waivers. You must sign
and submit each request for a waiver from the requirements in this
method in writing. The request must be submitted to the Group
Leader, Measurement Technology Group, U.S. Environmental Protection
Agency, E143-02, Research Triangle Park, NC 27711.
17.3 Information Application for Waiver. The request for
a waiver must contain a thorough description of the candidate test
method, the intended application, and results of any validation or
other supporting documents. The request for a waiver must contain,
at a minimum, the information in Sections 17.3.1 through 17.3.4 of
this method. The Administrator may request additional information
if necessary to determine whether this method can be waived for a
particular application.
17.3.1 A Clearly Written Test Method. The candidate test
method should be written preferably in the format of 40 CFR part
60, appendix A, Test Methods. Additionally, the candidate test must
include an applicability statement, concentration range, precision,
bias (accuracy), and minimum and maximum storage durations in which
samples must be analyzed.
17.3.2 Summaries of Previous Validation Tests or Other
Supporting Documents. If you use a different procedure from
that described in this method, you must submit documents
substantiating the bias and precision values to the Administrator's
satisfaction.
17.3.3 Ruggedness Testing Results. You must submit
results of ruggedness testing conducted according to Section 14.0
of this method, sample stability conducted according to Section 7.0
of this method, and detection limits conducted according to Section
15.0 of this method, as applicable. For example, you would not need
to submit ruggedness testing results if you will be using the
method at the same affected source and level at which it was
validated.
17.3.4 Applicability Statement and Basis for Waiver
Approval. Discussion of the applicability statement and basis
for approval of the waiver. This discussion should address as
applicable the following: applicable regulation, emission
standards, effluent characteristics, and process operations.
18.0 Where can I find additional information?
You can find additional information in the references in
Sections 18.1 through 18.18 of this method.
18.1 Albritton, J.R., G.B. Howe, S.B. Tompkins, R.K.M. Jayanty, and
C.E. Decker. 1989. Stability of Parts-Per-Million Organic Cylinder
Gases and Results of Source Test Analysis Audits, Status Report No.
11. Environmental Protection Agency Contract 68-02-4125. Research
Triangle Institute, Research Triangle Park, NC. September. 18.2
ASTM Standard E 1169-89 (current version), “Standard Guide for
Conducting Ruggedness Tests,” available from ASTM, 100 Barr Harbor
Drive, West Conshohoken, PA 19428. 18.3 DeWees, W.G., P.M. Grohse,
K.K. Luk, and F.E. Butler. 1989. Laboratory and Field Evaluation of
a Methodology for Speciating Nickel Emissions from Stationary
Sources. EPA Contract 68-02-4442. Prepared for Atmospheric Research
and Environmental Assessment Laboratory, Office of Research and
Development, U.S. Environmental Protection Agency, Research
Triangle Park, NC 27711. January. 18.4 International Conference on
Harmonization of Technical Requirements for the Registration of
Pharmaceuticals for Human Use, ICH-Q2A, “Text on Validation of
Analytical Procedures,” 60 FR 11260 (March 1995). 18.5
International Conference on Harmonization of Technical Requirements
for the Registration of Pharmaceuticals for Human Use, ICH-Q2b,
“Validation of Analytical Procedures: Methodology,” 62 FR 27464
(May 1997). 18.6 Keith, L.H., W. Crummer, J. Deegan Jr., R.A.
Libby, J.K. Taylor, and G. Wentler. 1983. Principles of
Environmental Analysis. American Chemical Society, Washington, DC.
18.7 Maxwell, E.A. 1974. Estimating variances from one or two
measurements on each sample. Amer. Statistician 28:96-97. 18.8
Midgett, M.R. 1977. How EPA Validates NSPS Methodology. Environ.
Sci. & Technol. 11(7):655-659. 18.9 Mitchell, W.J., and M.R.
Midgett. 1976. Means to evaluate performance of stationary source
test methods. Environ. Sci. & Technol. 10:85-88. 18.10 Plackett,
R.L., and J.P. Burman. 1946. The design of optimum multifactorial
experiments. Biometrika, 33:305. 18.11 Taylor, J.K. 1987. Quality
Assurance of Chemical Measurements. Lewis Publishers, Inc., pp.
79-81. 18.12 U.S. Environmental Protection Agency. 1978. Quality
Assurance Handbook for Air Pollution Measurement Systems: Volume
III. Stationary Source Specific Methods. Publication No.
EPA-600/4-77-027b. Office of Research and Development Publications,
26 West St. Clair St., Cincinnati, OH 45268. 18.13 U.S.
Environmental Protection Agency. 1981. A Procedure for Establishing
Traceability of Gas Mixtures to Certain National Bureau of
Standards Standard Reference Materials. Publication No.
EPA-600/7-81-010. Available from the U.S. EPA, Quality Assurance
Division (MD-77), Research Triangle Park, NC 27711. 18.14 U.S.
Environmental Protection Agency. 1991. Protocol for The Field
Validation of Emission Concentrations from Stationary Sources.
Publication No. 450/4-90-015. Available from the U.S. EPA, Emission
Measurement Technical Information Center, Technical Support
Division (MD-14), Research Triangle Park, NC 27711. 18.15
Wernimont, G.T., “Use of Statistics to Develop and Evaluate
Analytical Methods,” AOAC, 1111 North 19th Street, Suite 210,
Arlington, VA 22209, USA, 78-82 (1987). 18.16 Youden, W.J.
Statistical techniques for collaborative tests. In: Statistical
Manual of the Association of Official Analytical Chemists,
Association of Official Analytical Chemists, Washington, DC, 1975,
pp. 33-36. 18.17 NIST/SEMATECH (current version), “e-Handbook of
Statistical Methods,” available from NIST,
http://www.itl.nist.gov/div898/handbook/. 18.18 Statistical
Table,
http://www.math.usask.ca/∼szafron/Stats244/f_table_0_05.pdf.
19.0 Tables.
Table 301-1 - Sampling Procedures
If you are . . . |
You must collect . . . |
Comparing the
candidate test method against a validated method |
A total of 24 samples using a
quadruplicate sampling system (a total of six sets of replicate
samples). In each quadruplicate sample set, you must use the
validated test method to collect and analyze half of the
samples. |
Using isotopic
spiking (can only be used with methods capable of measurement of
multiple isotopes simultaneously) |
A total of 12 samples, all of
which are spiked with isotopically-labeled analyte. You may collect
the samples either by obtaining six sets of paired samples or three
sets of quadruplicate samples. |
Using analyte
spiking |
A total of 24 samples using
the quadruplicate sampling system (a total of six sets of replicate
samples - two spiked and two unspiked). |
Table 301-2 - Storage and Sampling
Procedures for Stack Test Emissions
If you are . . . |
With . . . |
Then you must . . . |
Using isotopic or
analyte spiking procedures |
Sample container (bag or
canister) or impinger sampling systems that are not subject to
dilution or other preparation steps |
Analyze six of the samples
within 7 days and then analyze the same six samples at the proposed
maximum storage duration or 2 weeks after the initial
analysis. |
|
Sorbent and impinger sampling
systems that require extraction or digestion |
Extract or digest six of the
samples within 7 days and extract or digest six other samples at
the proposed maximum storage duration or 2 weeks after the first
extraction or digestion. Analyze an aliquot of the first six
extracts (digestates) within 7 days and proposed maximum storage
duration or 2 weeks after the initial analysis. This will allow
analysis of extract storage impacts. |
|
Sorbent sampling systems that
require thermal desorption |
Analyze six samples within 7
days. Analyze another set of six samples at the proposed maximum
storage time or within 2 weeks of the initial analysis. |
Comparing a
candidate test method against a validated test method |
Sample container (bag or
canister) or impinger sampling systems that are not subject to
dilution or other preparation steps |
Analyze at least six of the
candidate test method samples within 7 days and then analyze the
same six samples at the proposed maximum storage duration or within
2 weeks of the initial analysis. |
|
Sorbent and impinger sampling
systems that require extraction or digestion |
Extract or digest six of the
candidate test method samples within 7 days and extract or digest
six other samples at the proposed maximum storage duration or
within 2 weeks of the first extraction or digestion. Analyze an
aliquot of the first six extracts (digestates) within 7 days and an
aliquot at the proposed maximum storage durations or within 2 weeks
of the initial analysis. This will allow analysis of extract
storage impacts. |
|
Sorbent systems that require
thermal desorption |
Analyze six samples within 7
days. Analyze another set of six samples at the proposed maximum
storage duration or within 2 weeks of the initial analysis. |
Table 301-3 - Critical Values of t for the
Two-Tailed 95 Percent Confidence Limit 1
Degrees of freedom |
t95 |
1 |
12.706 |
2 |
4.303 |
3 |
3.182 |
4 |
2.776 |
5 |
2.571 |
6 |
2.447 |
7 |
2.365 |
8 |
2.306 |
9 |
2.262 |
10 |
2.228 |
11 |
2.201 |
12 |
2.179 |
13 |
2.160 |
14 |
2.145 |
15 |
2.131 |
16 |
2.120 |
17 |
2.110 |
18 |
2.101 |
19 |
2.093 |
20 |
2.086 |
Table 301-4 - Upper Critical Values of the
F Distribution for the 95 Percent Confidence Limit 1
Numerator (k1) and
denominator (k2) degrees of freedom |
F{F>F.05(k1,k2)} |
1,1 |
161.40 |
2,2 |
19.00 |
3,3 |
9.28 |
4,4 |
6.39 |
5,5 |
5.05 |
6,6 |
4.28 |
7,7 |
3.79 |
8,8 |
3.44 |
9,9 |
3.18 |
10,10 |
2.98 |
11,11 |
2.82 |
12,12 |
2.69 |
13,13 |
2.58 |
14,14 |
2.48 |
15,15 |
2.40 |
16,16 |
2.33 |
17,17 |
2.27 |
18,18 |
2.22 |
19,19 |
2.17 |
20,20 |
2.12 |
Table 301-5 - Procedures for Estimating
So
|
|
If the estimated
LOD (LOD1, expected approximate LOD concentration level) is no more
than twice the calculated LOD or an analyte in a sample matrix was
collected prior to an analytical measurement, use Procedure I as
follows |
If the estimated LOD (LOD1,
expected approximate LOD concentration level) is greater than twice
the calculated LOD, use Procedure II as follows. |
Procedure I: |
Procedure II: |
Determine the
LOD by calculating a method detection limit (MDL) as described in
40 CFR part 136, appendix B |
Prepare two additional
standards (LOD2 and LOD3) at concentration levels lower than the
standard used in Procedure I (LOD1). |
|
Sample and analyze each of
these standards (LOD2 and LOD3) at least seven times. |
|
Calculate the standard
deviation (S2 and S3) for each concentration level. |
|
Plot the standard deviations
of the three test standards (S1, S2 and S3) as a function of
concentration. |
|
Draw a best-fit straight line
through the data points and extrapolate to zero concentration. The
standard deviation at zero concentration is So. |
|
Calculate the LOD0 (referred
to as the calculated LOD) as 3 times So. |
Method 303 - Determination of Visible Emissions From By-Product
Coke Oven Batteries Note:
This method is not inclusive with respect to observer
certification. Some material is incorporated by reference from
other methods in appendix A to 40 CFR part 60. Therefore, to obtain
reliable results, persons using this method should have a thorough
knowledge of Method 9.
1.0 Scope and Application
1.1 Applicability. This method is applicable for the
determination of visible emissions (VE) from the following
by-product coke oven battery sources: charging systems during
charging; doors, topside port lids, and offtake systems on
operating coke ovens; and collecting mains. This method is also
applicable for qualifying observers for visually determining the
presence of VE. In order for the test method results to be
indicative of plant performance, the time of day of the run should
vary.
2.0 Summary of Method
2.1 A certified observer visually determines the VE from coke
oven battery sources. Certification procedures are presented. This
method does not require that opacity of emissions be determined or
that magnitude be differentiated.
3.0 Definitions
3.1 Bench means the platform structure in front of the
oven doors.
3.2 By-product Coke Oven Battery means a source
consisting of a group of ovens connected by common walls, where
coal undergoes destructive distillation under positive pressure to
produce coke and coke oven gas, from which by-products are
recovered.
3.3 Charge or charging period means the period of time
that commences when coal begins to flow into an oven through a
topside port and ends when the last charging port is recapped.
3.4 Charging system means an apparatus used to charge
coal to a coke oven (e.g., a larry car for wet coal charging
systems).
3.5 Coke oven door means each end enclosure on the push
side and the coking side of an oven. The chuck, or leveler-bar,
door is considered part of the push side door. The coke oven door
area includes the entire area on the vertical face of a coke oven
between the bench and the top of the battery between two adjacent
buck stays.
3.6 Coke side means the side of a battery from which the
coke is discharged from ovens at the end of the coking cycle.
3.7 Collecting main means any apparatus that is connected
to one or more offtake systems and that provides a passage for
conveying gases under positive pressure from the by-product coke
oven battery to the by-product recovery system.
3.8 Consecutive charges means charges observed
successively, excluding any charge during which the observer's view
of the charging system or topside ports is obscured.
3.9 Damper-off means to close off the gas passage between
the coke oven and the collecting main, with no flow of raw coke
oven gas from the collecting main into the oven or into the oven's
offtake system(s).
3.10 Decarbonization period means the period of time for
combusting oven carbon that commences when the oven lids are
removed from an empty oven or when standpipe caps of an oven are
opened. The period ends with the initiation of the next charging
period for that oven.
3.11 Larry car means an apparatus used to charge coal to
a coke oven with a wet coal charging system.
3.12 Log average means logarithmic average as calculated
in Section 12.4.
3.13 Offtake system means any individual oven apparatus
that is stationary and provides a passage for gases from an oven to
a coke oven battery collecting main or to another oven. Offtake
system components include the standpipe and standpipe caps,
goosenecks, stationary jumper pipes, mini-standpipes, and standpipe
and gooseneck connections.
3.14 Operating oven means any oven not out of operation
for rebuild or maintenance work extensive enough to require the
oven to be skipped in the charging sequence.
3.15 Oven means a chamber in the coke oven battery in
which coal undergoes destructive distillation to produce coke.
3.16 Push side means the side of the battery from which
the coke is pushed from ovens at the end of the coking cycle.
3.17 Run means the observation of visible emissions from
topside port lids, offtake systems, coke oven doors, or the
charging of a single oven in accordance with this method.
3.18 Shed means an enclosure that covers the side of the
coke oven battery, captures emissions from pushing operations and
from leaking coke oven doors on the coke side or push side of the
coke oven battery, and routes the emissions to a control device or
system.
3.19 Standpipe cap means An apparatus used to cover the
opening in the gooseneck of an offtake system.
3.20 Topside port lid means a cover, removed during
charging or decarbonizing, that is placed over the opening through
which coal can be charged into the oven of a by-product coke oven
battery.
3.21 Traverse time means accumulated time for a traverse
as measured by a stopwatch. Traverse time includes time to stop and
write down oven numbers but excludes time waiting for obstructions
of view to clear or for time to walk around obstacles.
3.22 Visible Emissions or VE means any emission seen by
the unaided (except for corrective lenses) eye, excluding steam or
condensing water.
4.0 Interferences [Reserved] 5.0 Safety
5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of
the safety problems associated with its use. It is the
responsibility of the user of this test method to establish
appropriate safety and health practices and determine the
applicability of regulatory limitations prior to performing this
test method.
5.2 Safety Training. Because coke oven batteries have hazardous
environments, the training materials and the field training
(section 10.0) shall cover the precautions required to address
health and safety hazards.
6.0 Equipment and Supplies [Reserved] 7.0 Reagents and Standards
[Reserved] 8.0 Sample Collection, Preservation, Transport, and
Storage [Reserved] 9.0 Quality Control [Reserved] 10.0 Calibration
and Standardization
Observer certification and training requirements are as
follows:
10.1 Certification Procedures. This method requires only the
determination of whether VE occur and does not require the
determination of opacity levels; therefore, observer certification
according to Method 9 in appendix A to part 60 of this chapter is
not required to obtain certification under this method. However, in
order to receive Method 303 observer certification, the first-time
observer (trainee) shall have attended the lecture portion of the
Method 9 certification course. In addition, the trainee shall
successfully complete the Method 303 training course, satisfy the
field observation requirement, and demonstrate adequate performance
and sufficient knowledge of Method 303. The Method 303 training
provider and course shall be approved by the Administrator and
shall consist of classroom instruction, field training, and a
proficiency test. In order to apply for approval as a Method 303
training provider, an applicant must submit their credentials and
the details of their Method 303 training course to Group Leader,
Measurement Technology Group (E143-02), Office of Air Quality
Planning and Standards, U.S. Environmental Protection Agency,
Research Triangle Park, NC 27711. Those details should include, at
a minimum:
(a) A detailed list of the provider's credentials.
(b) An outline of the classroom and the field portions of the
class.
(c) Copies of the written training and lecture materials, to
include:
(1) The classroom audio-visual presentation(s).
(2) A classroom course manual with instructional text, practice
questions and problems for each of the elements of the Method 303
inspection (i.e., charging, doors, lids and offtakes, and
collecting mains). A copy of Method 303 and any related guidance
documents should be included as appendices.
(3) A copy of the Method 303 demonstration video, if not using
the one available at:
http://www3.epa.gov/ttn/emc/methods/method303trainingvideo.mp4.
(4) Multiple-choice certification tests, with questions
sufficient to demonstrate knowledge of the method, as follows: One
(1) Initial certification test and three (3) third-year
recertification tests (the questions on any one recertification
test must be at least 25 percent different from those on the other
recertification tests).
(5) A field certification checklist and inspection forms for
each of the elements of the Method 303 inspection (i.e.,
charging, doors, lids and offtakes, and collecting mains).
(6) The criteria used to determine proficiency.
(7) The panel members to be utilized (see Section 10.1.3) along
with their qualifications.
(8) An example certificate of successful course completion.
10.1.1 A trainee must verify completion of at least 12 hours of
field observation prior to attending the Method 303 certification
course. Trainees shall observe the operation of a coke oven battery
as it pertains to Method 303, including topside operations, and
shall also practice conducting Method 303 or similar methods.
During the field observations, trainees unfamiliar with coke
battery operations shall receive instruction from an experienced
coke oven observer who is familiar with Method 303 or similar
methods and with the operation of coke batteries.
10.1.2 The classroom instruction shall familiarize the trainees
with Method 303 through lecture, written training materials, and a
Method 303 demonstration video. Successful completion of the
classroom portion of the Method 303 training course shall be
demonstrated by a perfect score on the initial certification test.
Those attending the course for third-year recertification must
complete one of the recertification tests selected at random.
10.1.3 All trainees must demonstrate proficiency in the
application of Method 303 to a panel of three certified Method 303
observers, including an ability to differentiate coke oven
emissions from condensing water vapor and smoldering coal. The
composition of the panel must be approved by the Administrator as
part of the training course approval process. The panel members
will be EPA, state or local agency personnel, or industry
contractors listed in 59 FR 11960 (March 15, 1994) or qualified as
part of the training provider approval process of section 10.1 of
this method.
Each panel member shall have at least 120 days experience in
reading visible emissions from coke ovens. The visible emissions
inspections that will satisfy the experience requirement must be
inspections of coke oven battery fugitive emissions from the
emission points subject to emission standards under subpart L of
this part (i.e., coke oven doors, topside port lids, offtake
system(s), and charging operations), using either Method 303 or
predecessor state or local test methods. A “day's experience” for a
particular inspection is a day on which one complete inspection was
performed for that emission point under Method 303 or a predecessor
state or local method. A “day's experience” does not mean 8 or 10
hours performing inspections, or any particular time expressed in
minutes or hours that may have been spent performing them. Thus, it
would be possible for an individual to qualify as a Method 303
panel member for some emission points, but not others (e.g.,
an individual might satisfy the experience requirement for coke
oven doors, but not topside port lids). Until November 15, 1994,
the EPA may waive the certification requirement (but not the
experience requirement) for panel members. The composition of the
panel shall be approved by the EPA.
The panel shall observe the trainee in a series of training runs
and a series of certification runs. There shall be a minimum of 1
training run for doors, topside port lids, and offtake systems, and
a minimum of 5 training runs (i.e., 5 charges) for charging.
During training runs, the panel can advise the trainee on proper
procedures. There shall be a minimum of 3 certification runs for
doors, topside port lids, and offtake systems, and a minimum of 15
certification runs for charging (i.e., 15 charges). The
certification runs shall be unassisted. Following the certification
test runs, the panel shall approve or disapprove certification
based on the trainee's performance during the certification runs.
To obtain certification, the trainee shall demonstrate, to the
satisfaction of the panel, a high degree of proficiency in
performing Method 303. To aid in evaluating the trainee's
performance, a checklist, approved by the EPA, will be used by the
panel members.
10.1.4 Those successfully completing the initial certification
or third-year recertification requirements shall receive a
certificate showing certification as a Method 303 observer and the
beginning and ending dates of the certification period.
10.1.5 The training provider will submit to the EPA or its
designee the following information for each trainee successfully
completing initial certification or third-year recertification
training: Name, employer, address, telephone, cell and/or fax
numbers, email address, beginning and ending dates of
certification, and whether training was for 3-year certification or
1-year recertification. This information must be submitted within
30 days of the course completion.
10.1.6 The training provider will maintain the following
records, to be made available to EPA or its designee on request
(within 30 days of a request):
(a) A file for each Method 303 observer containing the signed
certification checklists, certification forms and test results for
their initial certification, and any subsequent third-year
recertifications. Initial certification records must also include
documentation showing successful completion of the training
prerequisites. Testing results from any interim recertifications
must also be included, along with any relevant communications.
(b) A searchable master electronic database of all persons for
whom initial certification, third-year recertification or interim
recertification. Information contained therein must include: The
observer's name, employer, address, telephone, cell and fax numbers
and email address, along with the beginning and ending dates for
each successfully completed initial, third-year and interim
recertification.
10.1.7 Failure by the training provider to submit example
training course materials and/or requested training records to the
Administrator may result in suspension of the approval of the
provider and course.
10.2 Observer Certification/Recertification. The coke oven
observer certification is valid for 1 year. The observer shall
recertify annually by reviewing the training material, viewing the
training video and answering all of the questions on the
recertification test correctly. Every 3 years, an observer shall be
required to pass the proficiency test in section 10.1.3 in order to
be certified. The years between proficiency tests are referred to
as interim years.
10.3 The EPA (or applicable enforcement agency) shall maintain
records reflecting a certified observer's successful completion of
the proficiency test, which shall include the completed proficiency
test checklists for the certification runs.
10.4 An owner or operator of a coke oven battery subject to
subpart L of this part may observe a training and certification
program under this section.
11.0 Procedure
11.1 Procedure for Determining VE from Charging Systems During
Charging.
11.1.1 Number of Oven Charges. Refer to § 63.309(c)(1) of this
part for the number of oven charges to observe. The observer shall
observe consecutive charges. Charges that are nonconsecutive can
only be observed when necessary to replace observations terminated
prior to the completion of a charge because of visual
interferences. (See Section 11.1.5).
11.1.2 Data Records. Record all the information requested at the
top of the charging system inspection sheet (Figure 303-1). For
each charge, record the identification number of the oven being
charged, the approximate beginning time of the charge, and the
identification of the larry car used for the charge.
11.1.3 Observer Position. Stand in an area or move to positions
on the topside of the coke oven battery with an unobstructed view
of the entire charging system. For wet coal charging systems or
non-pipeline coal charging systems, the observer should have an
unobstructed view of the emission points of the charging system,
including larry car hoppers, drop sleeves, and the topside ports of
the oven being charged. Some charging systems are configured so
that all emission points can only be seen from a distance of five
ovens. For other batteries, distances of 8 to 12 ovens are
adequate.
11.1.4 Observation. The charging period begins when coal begins
to flow into the oven and ends when the last charging port is
recapped. During the charging period, observe all of the potential
sources of VE from the entire charging system. For wet coal
charging systems or non-pipeline coal charging systems, sources of
VE typically include the larry car hoppers, drop sleeves, slide
gates, and topside ports on the oven being charged. Any VE from an
open standpipe cap on the oven being charged is included as
charging VE.
11.1.4.1 Using an accumulative-type stopwatch with unit
divisions of at least 0.5 seconds, determine the total time VE are
observed as follows. Upon observing any VE emerging from any part
of the charging system, start the stopwatch. Stop the watch when VE
are no longer observed emerging, and restart the watch when VE
reemerges.
11.1.4.2 When VE occur simultaneously from several points during
a charge, consider the sources as one. Time overlapping VE as
continuous VE. Time single puffs of VE only for the time it takes
for the puff to emerge from the charging system. Continue to time
VE in this manner for the entire charging period. Record the
accumulated time to the nearest 0.5 second under “Visible
emissions, seconds” on Figure 303-1.
11.1.5 Visual Interference. If fugitive VE from other sources at
the coke oven battery site (e.g., door leaks or condensing
water vapor from the coke oven wharf) prevent a clear view of the
charging system during a charge, stop the stopwatch and make an
appropriate notation under “Comments” on Figure 303-1. Label the
observation an observation of an incomplete charge, and observe
another charge to fulfill the requirements of Section 11.1.1.
11.1.6 VE Exemptions. Do not time the following VE:
11.1.6.1 The VE from burning or smoldering coal spilled on top
of the oven, topside port lid, or larry car surfaces;
Note:
The VE from smoldering coal are generally white or gray. These
VE generally have a plume of less than 1 meter long. If the
observer cannot safely and with reasonable confidence determine
that VE are from charging, do not count them as charging
emissions.
11.1.6.2 The VE from the coke oven doors or from the leveler
bar; or
11.1.6.3 The VE that drift from the top of a larry car hopper if
the emissions had already been timed as VE from the drop
sleeve.
Note:
When the slide gate on a larry car hopper closes after the coal
has been added to the oven, the seal may not be airtight. On
occasions, a puff of smoke observed at the drop sleeves is forced
past the slide gate up into the larry car hopper and may drift from
the top; time these VE either at the drop sleeves or the hopper. If
the larry car hopper does not have a slide gate or the slide gate
is left open or partially closed, VE may quickly pass through the
larry car hopper without being observed at the drop sleeves and
will appear as a strong surge of smoke; time these as charging
VE.
11.1.7 Total Time Record. Record the total time that VE were
observed for each charging operation in the appropriate column on
the charging system inspection sheet.
11.1.8 Determination of Validity of a Set of Observations. Five
charging observations (runs) obtained in accordance with this
method shall be considered a valid set of observations for that
day. No observation of an incomplete charge shall be included in a
daily set of observations that is lower than the lowest reading for
a complete charge. If both complete and incomplete charges have
been observed, the daily set of observations shall include the five
highest values observed. Four or three charging observations (runs)
obtained in accordance with this method shall be considered a valid
set of charging observations only where it is not possible to
obtain five charging observations, because visual interferences
(see Section 11.1.5) or inclement weather prevent a clear view of
the charging system during charging. However, observations from
three or four charges that satisfy these requirements shall not be
considered a valid set of charging observations if use of such set
of observations in a calculation under Section 12.4 would cause the
value of A to be less than 145.
11.1.9 Log Average. For each day on which a valid daily set of
observations is obtained, calculate the daily 30-day rolling log
average of seconds of visible emissions from the charging operation
for each battery using these data and the 29 previous valid daily
sets of observations, in accordance with Section 12.4.
11.2. Procedure for Determining VE from Coke Oven Door Areas.
The intent of this procedure is to determine VE from coke oven door
areas by carefully observing the door area from a standard distance
while walking at a normal pace.
11.2.1 Number of Runs. Refer to § 63.309(c)(1) of this part for
the appropriate number of runs.
11.2.2 Battery Traverse. To conduct a battery traverse, walk the
length of the battery on the outside of the pusher machine and
quench car tracks at a steady, normal walking pace, pausing to make
appropriate entries on the door area inspection sheet (Figure
303-2). A single test run consists of two timed traverses, one for
the coke side and one for the push side. The walking pace shall be
such that the duration of the traverse does not exceed an average
of 4 seconds per oven door, excluding time spent moving around
stationary obstructions or waiting for other obstructions to move
from positions blocking the view of a series of doors. Extra time
is allowed for each leak (a maximum of 10 additional seconds for
each leaking door) for the observer to make the proper notation. A
walking pace of 3 seconds per oven door has been found to be
typical. Record the actual traverse time with a stopwatch.
11.2.2.1 Include in the traverse time only the time spent
observing the doors and recording door leaks. To measure actual
traverse time, use an accumulative-type stopwatch with unit
divisions of 0.5 seconds or less. Exclude interruptions to the
traverse and time required for the observer to move to positions
where the view of the battery is unobstructed, or for obstructions,
such as the door machine, to move from positions blocking the view
of a series of doors.
11.2.2.2 Various situations may arise that will prevent the
observer from viewing a door or a series of doors. Prior to the
door inspection, the owner or operator may elect to temporarily
suspend charging operations for the duration of the inspection, so
that all of the doors can be viewed by the observer. The observer
has two options for dealing with obstructions to view: (a) Stop the
stopwatch and wait for the equipment to move or the fugitive
emissions to dissipate before completing the traverse; or (b) stop
the stopwatch, skip the affected ovens, and move to an unobstructed
position to continue the traverse. Restart the stopwatch and
continue the traverse. After the completion of the traverse, if the
equipment has moved or the fugitive emissions have dissipated,
inspect the affected doors. If the equipment is still preventing
the observer from viewing the doors, then the affected doors may be
counted as not observed. If option (b) is used because of doors
blocked by machines during charging operations, then, of the
affected doors, exclude the door from the most recently charged
oven from the inspection. Record the oven numbers and make an
appropriate notation under “Comments” on the door area inspection
sheet (Figure 303-2).
11.2.2.3 When batteries have sheds to control emissions, conduct
the inspection from outside the shed unless the doors cannot be
adequately viewed. In this case, conduct the inspection from the
bench. Be aware of special safety considerations pertinent to
walking on the bench and follow the instructions of company
personnel on the required equipment and procedures. If possible,
conduct the bench traverse whenever the bench is clear of the door
machine and hot coke guide.
11.2.3 Observations. Record all the information requested at the
top of the door area inspection sheet (Figure 303-2), including the
number of non-operating ovens. Record the clock time at the start
of the traverse on each side of the battery. Record which side is
being inspected (i.e., coke side or push side). Other
information may be recorded at the discretion of the observer, such
as the location of the leak (e.g., top of the door, chuck
door, etc.), the reason for any interruption of the traverse, or
the position of the sun relative to the battery and sky conditions
(e.g., overcast, partly sunny, etc.).
11.2.3.1 Begin the test run by starting the stopwatch and
traversing either the coke side or the push side of the battery.
After completing one side, stop the watch. Complete this procedure
on the other side. If inspecting more than one battery, the
observer may view the push sides and the coke sides
sequentially.
11.2.3.2 During the traverse, look around the entire perimeter
of each oven door. The door is considered leaking if VE are
detected in the coke oven door area. The coke oven door area
includes the entire area on the vertical face of a coke oven
between the bench and the top of the battery between two adjacent
buck stays (e.g., the oven door, chuck door, between the
masonry brick, buck stay or jamb, or other sources). Record the
oven number and make the appropriate notation on the door area
inspection sheet (Figure 303-2).
Note:
Multiple VE from the same door area (e.g., VE from both
the chuck door and the push side door) are counted as only one
emitting door, not as multiple emitting doors.
11.2.3.3 Do not record the following sources as door area
VE:
11.2.3.3.1 VE from ovens with doors removed. Record the oven
number and make an appropriate notation under “Comments;”
11.2.3.3.2 VE from ovens taken out of service. The owner or
operator shall notify the observer as to which ovens are out of
service. Record the oven number and make an appropriate notation
under “Comments;” or
11.2.3.3.3 VE from hot coke that has been spilled on the bench
as a result of pushing.
11.2.4 Criteria for Acceptance. After completing the run,
calculate the maximum time allowed to observe the ovens using the
equation in Section 12.2. If the total traverse time exceeds T,
void the run, and conduct another run to satisfy the requirements
of § 63.309(c)(1) of this part.
11.2.5 Percent Leaking Doors. For each day on which a valid
observation is obtained, calculate the daily 30-day rolling average
for each battery using these data and the 29 previous valid daily
observations, in accordance with Section 12.5.
11.3 Procedure for Determining VE from Topside Port Lids and
Offtake Systems.
11.3.1 Number of Runs. Refer to § 63.309(c)(1) of this part for
the number of runs to be conducted. Simultaneous runs or separate
runs for the topside port lids and offtake systems may be
conducted.
11.3.2 Battery Traverse. To conduct a topside traverse of the
battery, walk the length of the battery at a steady, normal walking
pace, pausing only to make appropriate entries on the topside
inspection sheet (Figure 303-3). The walking pace shall not exceed
an average rate of 4 seconds per oven, excluding time spent moving
around stationary obstructions or waiting for other obstructions to
move from positions blocking the view. Extra time is allowed for
each leak for the observer to make the proper notation. A walking
pace of 3 seconds per oven is typical. Record the actual traverse
time with a stopwatch.
11.3.3 Topside Port Lid Observations. To observe lids of the
ovens involved in the charging operation, the observer shall wait
to view the lids until approximately 5 minutes after the completion
of the charge. Record all the information requested on the topside
inspection sheet (Figure 303-3). Record the clock time when
traverses begin and end. If the observer's view is obstructed
during the traverse (e.g., steam from the coke wharf, larry
car, etc.), follow the guidelines given in Section 11.2.2.2.
11.3.3.1 To perform a test run, conduct a single traverse on the
topside of the battery. The observer shall walk near the center of
the battery but may deviate from this path to avoid safety hazards
(such as open or closed charging ports, luting buckets, lid removal
bars, and topside port lids that have been removed) and any other
obstacles. Upon noting VE from the topside port lid(s) of an oven,
record the oven number and port number, then resume the traverse.
If any oven is dampered-off from the collecting main for
decarbonization, note this under “Comments” for that particular
oven.
Note:
Count the number of topside ports, not the number of points,
exhibiting VE, i.e., if a topside port has several points of
VE, count this as one port exhibiting VE.
11.3.3.2 Do not count the following as topside port lid VE:
11.3.3.2.1 VE from between the brickwork and oven lid casing or
VE from cracks in the oven brickwork. Note these VE under
“Comments;”
11.3.3.2.2 VE from topside ports involved in a charging
operation. Record the oven number, and make an appropriate notation
(e.g., not observed because ports open for charging) under
“Comments;”
11.3.3.2.3 Topside ports having maintenance work done. Record
the oven number and make an appropriate notation under “Comments;”
or
11.3.3.2.4 Condensing water from wet-sealing material. Ports
with only visible condensing water from wet-sealing material are
counted as observed but not as having VE.
11.3.3.2.5 Visible emissions from the flue inspection ports and
caps.
11.3.4 Offtake Systems Observations. To perform a test run,
traverse the battery as in Section 11.3.3.1. Look ahead and back
two to four ovens to get a clear view of the entire offtake system
for each oven. Consider visible emissions from the following points
as offtake system VE: (a) the flange between the gooseneck and
collecting main (“saddle”), (b) the junction point of the standpipe
and oven (“standpipe base”), (c) the other parts of the offtake
system (e.g., the standpipe cap), and (d) the junction
points with ovens and flanges of jumper pipes.
11.3.4.1 Do not stray from the traverse line in order to get a
“closer look” at any part of the offtake system unless it is to
distinguish leaks from interferences from other sources or to avoid
obstacles.
11.3.4.2 If the centerline does not provide a clear view of the
entire offtake system for each oven (e.g., when standpipes
are longer than 15 feet), the observer may conduct the traverse
farther from (rather than closer to) the offtake systems.
11.3.4.3 Upon noting a leak from an offtake system during a
traverse, record the oven number. Resume the traverse. If the oven
is dampered-off from the collecting main for decarbonization and VE
are observed, note this under “Comments” for that particular
oven.
11.3.4.4 If any part or parts of an offtake system have VE,
count it as one emitting offtake system. Each stationary jumper
pipe is considered a single offtake system.
11.3.4.5 Do not count standpipe caps open for a decarbonization
period or standpipes of an oven being charged as source of offtake
system VE. Record the oven number and write “Not observed” and the
reason (i.e., decarb or charging) under “Comments.”
Note:
VE from open standpipes of an oven being charged count as
charging emissions. All VE from closed standpipe caps count as
offtake leaks.
11.3.5 Criteria for Acceptance. After completing the run (allow
2 traverses for batteries with double mains), calculate the maximum
time allowed to observe the topside port lids and/or offtake
systems using the equation in Section 12.3. If the total traverse
time exceeds T, void the run and conduct another run to satisfy the
requirements of § 63.309(c)(1) of this part.
11.3.6 In determining the percent leaking topside port lids and
percent leaking offtake systems, do not include topside port lids
or offtake systems with VE from the following ovens:
11.3.6.1 Empty ovens, including ovens undergoing maintenance,
which are properly dampered off from the main.
11.3.6.2 Ovens being charged or being pushed.
11.3.6.3 Up to 3 full ovens that have been dampered off from the
main prior to pushing.
11.3.6.4 Up to 3 additional full ovens in the pushing sequence
that have been dampered off from the main for offtake system
cleaning, for decarbonization, for safety reasons, or when a
charging/pushing schedule involves widely separated ovens (e.g., a
Marquard system); or that have been dampered off from the main for
maintenance near the end of the coking cycle. Examples of reasons
that ovens are dampered off for safety reasons are to avoid
exposing workers in areas with insufficient clearance between
standpipes and the larry car, or in areas where workers could be
exposed to flames or hot gases from open standpipes, and to avoid
the potential for removing a door on an oven that is not dampered
off from the main.
11.3.7 Percent Leaking Topside Port Lids and Offtake Systems.
For each day on which a valid observation is obtained, calculate
the daily 30-day rolling average for each battery using these data
and the 29 previous valid daily observations, in accordance with
Sections 12.6 and 12.7.
11.4 Procedure for Determining VE from Collecting Mains.
11.4.1 Traverse. To perform a test run, traverse both the
collecting main catwalk and the battery topside along the side
closest to the collecting main. If the battery has a double main,
conduct two sets of traverses for each run, i.e., one set for each
main.
11.4.2 Data Recording. Upon noting VE from any portion of a
collection main, identify the source and approximate location of
the source of VE and record the time under “Collecting main” on
Figure 303-3; then resume the traverse.
11.4.3 Collecting Main Pressure Check. After the completion of
the door traverse, the topside port lids, and offtake systems,
compare the collecting main pressure during the inspection to the
collecting main pressure during the previous 8 to 24 hours. Record
the following: (a) the pressure during inspection, (b) presence of
pressure deviation from normal operations, and (c) the explanation
for any pressure deviation from normal operations, if any, offered
by the operators. The owner or operator of the coke battery shall
maintain the pressure recording equipment and conduct the quality
assurance/quality control (QA/QC) necessary to ensure reliable
pressure readings and shall keep the QA/QC records for at least 6
months. The observer may periodically check the QA/QC records to
determine their completeness. The owner or operator shall provide
access to the records within 1 hour of an observer's request.
12.0 Data Analysis and Calculations
12.1 Nomenclature.
A = 150 or the number of valid observations (runs). The value of A
shall not be less than 145, except for purposes of determinations
under § 63.306(c) (work practice plan implementation) or §
63.306(d) (work practice plan revisions) of this part. No set of
observations shall be considered valid for such a recalculation
that otherwise would not be considered a valid set of observations
for a calculation under this paragraph. Di = Number of doors on
non-operating ovens. Dno = Number of doors not observed. Dob =
Total number of doors observed on operating ovens. Dt = Total
number of oven doors on the battery. e = 2.72 J = Number of
stationary jumper pipes. L = Number of doors with VE. Lb =
Yard-equivalent reading. Ls = Number of doors with VE observed from
the bench under sheds. Ly = Number of doors with VE observed from
the yard. Ly = Number of doors with VE observed from the yard on
the push side. ln = Natural logarithm. N = Total number of ovens in
the battery. Ni = Total number of inoperable ovens. PNO = Number of
ports not observed. Povn = Number of ports per oven. PVE = Number
of topside port lids with VE. PLD = Percent leaking coke oven doors
for the test run. PLL = Percent leaking topside port lids for the
run. PLO = Percent leaking offtake systems. T = Total time allowed
for traverse, seconds. Tovn = Number of offtake systems (excluding
jumper pipes) per oven. TNO = Number of offtake systems not
observed. TVE = Number of offtake systems with VE. Xi = Seconds of
VE during the ith charge. Z = Number of topside port lids or
offtake systems with VE.
12.2 Criteria for Acceptance for VE Determinations from Coke
Oven Door Areas. After completing the run, calculate the maximum
time allowed to observe the ovens using the following equation:
12.3 Criteria for Acceptance for VE Determinations from Topside
Port Lids and Offtake Systems. After completing the run (allow 2
traverses for batteries with double mains), calculate the maximum
time allowed to observe the topside port lids and/or offtake
systems by the following equation:
12.4 Average Duration of VE from Charging Operations. Use
Equation 303-3 to calculate the daily 30-day rolling log average of
seconds of visible emissions from the charging operation for each
battery using these current day's observations and the 29 previous
valid daily sets of observations.
12.5 Percent Leaking Doors (PLD). Determine the total number of
doors for which observations were made on the coke oven battery as
follows:
12.5.1 For each test run (one run includes both the coke side
and the push side traverses), sum the number of doors with door
area VE. For batteries subject to an approved alternative standard
under § 63.305 of this part, calculate the push side and the coke
side PLD separately.
12.5.2 Calculate percent leaking doors by using Equation
303-5:
12.5.3 When traverses are conducted from the bench under sheds,
calculate the coke side and the push side separately. Use Equation
303-6 to calculate a yard-equivalent reading:
![]()
If Lb is less than zero, use zero for Lb in
Equation 303-7 in the calculation of PLD.
12.5.3.1 Use Equation 303-7 to calculate PLD:
![]()
Round off PLD to the nearest hundredth of 1
percent and record as the percent leaking coke oven doors for the
run.
12.5.3.2 Average Percent Leaking Doors. Use Equation 303-8 to
calculate the daily 30-day rolling average percent leaking doors
for each battery using these current day's observations and the 29
previous valid daily sets of observations.
12.6 Topside Port Lids. Determine the percent leaking topside
port lids for each run as follows:
12.6.1 Round off this percentage to the nearest hundredth of 1
percent and record this percentage as the percent leaking topside
port lids for the run.
12.6.2 Average Percent Leaking Topside Port Lids. Use Equation
303-10 to calculate the daily 30-day rolling average percent
leaking topside port lids for each battery using these current
day's observations and the 29 previous valid daily sets of
observations.
12.7 Offtake Systems. Determine the percent leaking offtake
systems for the run as follows:
12.7.1 Round off this percentage to the nearest hundredth of 1
percent and record this percentage as the percent leaking offtake
systems for the run.
12.7.2 Average Percent Leaking Offtake Systems. Use Equation
303-12 to calculate the daily 30-day rolling average percent
leaking offtake systems for each battery using these current day's
observations and the 29 previous valid daily sets of
observations.
![]()
13.0 Method Performance [Reserved] 14.0
Pollution Prevention [Reserved] 15.0 Waste Management [Reserved]
16.0 References.
1. Missan, R., and A. Stein. Guidelines for Evaluation of
Visible Emissions Certification, Field Procedures, Legal Aspects,
and Background Material. U.S. Environmental Protection Agency. EPA
Publication No. EPA-340/1-75-007. April 1975.
2. Wohlschlegel, P., and D. E. Wagoner. Guideline for
Development of a Quality Assurance Program: Volume IX - Visual
Determination of Opacity Emission from Stationary Sources. U.S.
Environmental Protection Agency. EPA Publication No.
EPA-650/4-74-005i. November 1975.
3. U.S. Occupational Safety and Health Administration. Code of
Federal Regulations. Title 29, Chapter XVII, Section 1910.1029(g).
Washington, D.C. Government Printing Office. July 1, 1990.
4. U.S. Environmental Protection Agency. National Emission
Standards for Hazardous Air Pollutants; Coke Oven Emissions from
Wet-Coal Charged By-Product Coke Oven Batteries; Proposed Rule and
Notice of Public Hearing. Washington, D.C. Federal Register. Vol.
52, No. 78 (13586). April 23, 1987.
17.0 Tables, Diagrams, Flowcharts, and Validation Data Company
name: Battery no.: ___ Date: ___ Run no.: ___ City, State: Observer
name: Company representative(s):
Charge No. |
Oven
No. |
Clock time |
Visible
emissions,
seconds |
Comments |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Figure 303-1. Charging System Inspection Company name: Battery no.:
Date: City, State: Total no. of ovens in battery: Observer name:
Certification expiration date: Inoperable ovens: Company
representative(s): Traverse time CS: Traverse time PS: Valid run (Y
or N):
Time traverse
started/completed |
PS/CS |
Door No. |
Comments
(No. of blocked doors, interruptions to traverse, etc.) |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Figure 303-2. Door Area Inspection. Company name: Battery no.:
Date: City, State: Total no. of ovens in battery: Observer name:
Certification expiration date: Inoperable ovens: Company
representative(s): Total no. of lids: Total no. of offtakes: Total
no. of jumper pipes: Ovens not observed: Total traverse time: Valid
run (Y or N):
Time traverse
started/completed |
Type of Inspection
(lids, offtakes, collecting main) |
Location of VE
(Oven #/Port #) |
Comments |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Figure 303-3. Topside Inspection Method 303A - Determination of
Visible Emissions From Nonrecovery Coke Oven Batteries Note:
This method does not include all of the specifications
pertaining to observer certification. Some material is incorporated
by reference from other methods in this part and in appendix A to
40 CFR Part 60. Therefore, to obtain reliable results, persons
using this method should have a thorough knowledge of Method 9 and
Method 303.
1.0 Scope and Application
1.1 Applicability. This method is applicable for the
determination of visible emissions (VE) from leaking doors at
nonrecovery coke oven batteries.
2.0 Summary of Method
2.1 A certified observer visually determines the VE from coke
oven battery sources while walking at a normal pace. This method
does not require that opacity of emissions be determined or that
magnitude be differentiated.
3.0 Definitions
3.1 Bench means the platform structure in front of the
oven doors.
3.2 Coke oven door means each end enclosure on the push
side and the coking side of an oven.
3.3 Coke side means the side of a battery from which the
coke is discharged from ovens at the end of the coking cycle.
3.4 Nonrecovery coke oven battery means a source
consisting of a group of ovens connected by common walls and
operated as a unit, where coal undergoes destructive distillation
under negative pressure to produce coke, and which is designed for
the combustion of coke oven gas from which by-products are not
recovered.
3.5 Operating oven means any oven not out of operation
for rebuild or maintenance work extensive enough to require the
oven to be skipped in the charging sequence.
3.6 Oven means a chamber in the coke oven battery in
which coal undergoes destructive distillation to produce coke.
3.7 Push side means the side of the battery from which
the coke is pushed from ovens at the end of the coking cycle.
3.8 Run means the observation of visible emissions from
coke oven doors in accordance with this method.
3.9 Shed means an enclosure that covers the side of the
coke oven battery, captures emissions from pushing operations and
from leaking coke oven doors on the coke side or push side of the
coke oven battery, and routes the emissions to a control device or
system.
3.10 Traverse time means accumulated time for a traverse
as measured by a stopwatch. Traverse time includes time to stop and
write down oven numbers but excludes time waiting for obstructions
of view to clear or for time to walk around obstacles.
3.11 Visible Emissions or VE means any emission seen by
the unaided (except for corrective lenses) eye, excluding steam or
condensing water.
4.0 Interferences [Reserved] 5.0 Safety
5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of
the safety problems associated with its use. It is the
responsibility of the user of this test method to establish
appropriate safety and health practices and determine the
applicability of regulatory limitations prior to performing this
test method.
5.2 Safety Training. Because coke oven batteries have hazardous
environments, the training materials and the field training
(Section 10.0) shall cover the precautions required by the company
to address health and safety hazards. Special emphasis shall be
given to the Occupational Safety and Health Administration (OSHA)
regulations pertaining to exposure of coke oven workers (see
Reference 3 in Section 16.0). In general, the regulation requires
that special fire-retardant clothing and respirators be worn in
certain restricted areas of the coke oven battery. The OSHA
regulation also prohibits certain activities, such as chewing gum,
smoking, and eating in these areas.
6.0 Equipment and Supplies [Reserved] 7.0 Reagents and Standards
[Reserved] 8.0 Sample Collection, Preservation, Transport, and
Storage [Reserved] 9.0 Quality Control [Reserved] 10.0 Calibration
and Standardization.
10.1 Training. This method requires only the determination of
whether VE occur and does not require the determination of opacity
levels; therefore, observer certification according to Method 9 in
Appendix A to Part 60 is not required. However, the first-time
observer (trainee) shall have attended the lecture portion of the
Method 9 certification course. Furthermore, before conducting any
VE observations, an observer shall become familiar with nonrecovery
coke oven battery operations and with this test method by observing
for a minimum of 4 hours the operation of a nonrecovery coke oven
battery in the presence of personnel experienced in performing
Method 303 assessments.
11.0 Procedure
The intent of this procedure is to determine VE from coke oven
door areas by carefully observing the door area while walking at a
normal pace.
11.1 Number of Runs. Refer to § 63.309(c)(1) of this part for
the appropriate number of runs.
11.2 Battery Traverse. To conduct a battery traverse, walk the
length of the battery on the outside of the pusher machine and
quench car tracks at a steady, normal walking pace, pausing to make
appropriate entries on the door area inspection sheet (Figure
303A-1). The walking pace shall be such that the duration of the
traverse does not exceed an average of 4 seconds per oven door,
excluding time spent moving around stationary obstructions or
waiting for other obstructions to move from positions blocking the
view of a series of doors. Extra time is allowed for each leak (a
maximum of 10 additional seconds for each leaking door) for the
observer to make the proper notation. A walking pace of 3 seconds
per oven door has been found to be typical. Record the actual
traverse time with a stopwatch. A single test run consists of two
timed traverses, one for the coke side and one for the push
side.
11.2.1 Various situations may arise that will prevent the
observer from viewing a door or a series of doors. The observer has
two options for dealing with obstructions to view: (a) Wait for the
equipment to move or the fugitive emissions to dissipate before
completing the traverse; or (b) skip the affected ovens and move to
an unobstructed position to continue the traverse. Continue the
traverse. After the completion of the traverse, if the equipment
has moved or the fugitive emissions have dissipated, complete the
traverse by inspecting the affected doors. Record the oven numbers
and make an appropriate notation under “Comments” on the door area
inspection sheet (Figure 303A-1).
Note:
Extra time incurred for handling obstructions is not counted in
the traverse time.
11.2.2 When batteries have sheds to control pushing emissions,
conduct the inspection from outside the shed, if the shed allows
such observations, or from the bench. Be aware of special safety
considerations pertinent to walking on the bench and follow the
instructions of company personnel on the required equipment and
operations procedures. If possible, conduct the bench traverse
whenever the bench is clear of the door machine and hot coke
guide.
11.3 Observations. Record all the information requested at the
top of the door area inspection sheet (Figure 303A-1), including
the number of non-operating ovens. Record which side is being
inspected, i.e., coke side or push side. Other information
may be recorded at the discretion of the observer, such as the
location of the leak (e.g., top of the door), the reason for
any interruption of the traverse, or the position of the sun
relative to the battery and sky conditions (e.g., overcast,
partly sunny, etc.).
11.3.1 Begin the test run by traversing either the coke side or
the push side of the battery. After completing one side, traverse
the other side.
11.3.2 During the traverse, look around the entire perimeter of
each oven door. The door is considered leaking if VE are detected
in the coke oven door area. The coke oven door area includes the
entire area on the vertical face of a coke oven between the bench
and the top of the battery and the adjacent doors on both sides.
Record the oven number and make the appropriate notation on the
door area inspection sheet (Figure 303A-1).
11.3.3 Do not record the following sources as door area VE:
11.3.3.1 VE from ovens with doors removed. Record the oven
number and make an appropriate notation under “Comments”;
11.3.3.2 VE from ovens where maintenance work is being
conducted. Record the oven number and make an appropriate notation
under “Comments”; or
11.3.3.3 VE from hot coke that has been spilled on the bench as
a result of pushing.
12.0 Data Analysis and Calculations
Same as Method 303, Section 12.1, 12.2, 12.3, 12.4, and
12.5.
13.0 Method Performance [Reserved] 14.0 Pollution Prevention
[Reserved] 15.0 Waste Management [Reserved] 16.0 References
Same as Method 303, Section 16.0.
17.0 Tables, Diagrams, Flowcharts, and Validation Data Company
name: Battery no.: Date: City, State: Total no. of ovens in
battery: Observer name: Certification expiration date: Inoperable
ovens: Company representative(s): Traverse time CS: Traverse time
PS: Valid run (Y or N):
Time traverse
started/completed |
PS/CS |
Door No. |
Comments
(No. of blocked doors, interruptions to traverse, etc.) |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Figure 303A-1. Door Area Inspection Method 304A: Determination of
Biodegradation Rates of Organic Compounds (Vent Option) 1.0 Scope
and Application
1.1 Applicability. This method is applicable for the
determination of biodegradation rates of organic compounds in an
activated sludge process. The test method is designed to evaluate
the ability of an aerobic biological reaction system to degrade or
destroy specific components in waste streams. The method may also
be used to determine the effects of changes in wastewater
composition on operation. The biodegradation rates determined by
utilizing this method are not representative of a full-scale
system. The rates measured by this method shall be used in
conjunction with the procedures listed in appendix C of this part
to calculate the fraction emitted to the air versus the fraction
biodegraded.
2.0 Summary of Method
2.1 A self-contained benchtop bioreactor system is assembled in
the laboratory. A sample of mixed liquor is added and the waste
stream is then fed continuously. The benchtop bioreactor is
operated under conditions nearly identical to the target full-scale
activated sludge process. Bioreactor temperature, dissolved oxygen
concentration, average residence time in the reactor, waste
composition, biomass concentration, and biomass composition of the
full-scale process are the parameters which are duplicated in the
benchtop bioreactor. Biomass shall be removed from the target
full-scale activated sludge unit and held for no more than 4 hours
prior to use in the benchtop bioreactor. If antifoaming agents are
used in the full-scale system, they shall also be used in the
benchtop bioreactor. The feed flowing into and the effluent exiting
the benchtop bioreactor are analyzed to determine the
biodegradation rates of the target compounds. The flow rate of the
exit vent is used to calculate the concentration of target
compounds (utilizing Henry's law) in the exit gas stream. If
Henry's law constants for the compounds of interest are not known,
this method cannot be used in the determination of the
biodegradation rate and Method 304B is the suggested method. The
choice of analytical methodology for measuring the compounds of
interest at the inlet and outlet to the benchtop bioreactor are
left to the discretion of the source, except where validated
methods are available.
3.0 Definitions [Reserved] 4.0 Interferences [Reserved] 5.0 Safety
5.1 If explosive gases are produced as a byproduct of
biodegradation and could realistically pose a hazard, closely
monitor headspace concentration of these gases to ensure laboratory
safety. Placement of the benchtop bioreactor system inside a
laboratory hood is recommended regardless of byproducts
produced.
6.0. Equipment and Supplies Note:
Figure 304A-1 illustrates a typical laboratory apparatus used to
measure biodegradation rates. While the following description
refers to Figure 304A-1, the EPA recognizes that alternative
reactor configurations, such as alternative reactor shapes and
locations of probes and the feed inlet, will also meet the intent
of this method. Ensure that the benchtop bioreactor system is
self-contained and isolated from the atmosphere (except for the
exit vent stream) by leak-checking fittings, tubing, etc.
6.1 Benchtop Bioreactor. The biological reaction is conducted in
a biological oxidation reactor of at least 6 liters capacity. The
benchtop bioreactor is sealed and equipped with internal probes for
controlling and monitoring dissolved oxygen and internal
temperature. The top of the reactor is equipped for aerators, gas
flow ports, and instrumentation (while ensuring that no leaks to
the atmosphere exist around the fittings).
6.2 Aeration gas. Aeration gas is added to the benchtop
bioreactor through three diffusers, which are glass tubes that
extend to the bottom fifth of the reactor depth. A pure oxygen
pressurized cylinder is recommended in order to maintain the
specified oxygen concentration. Install a blower (e.g.,
Diaphragm Type, 15 SCFH capacity) to blow the aeration gas into the
reactor diffusers. Measure the aeration gas flow rate with a
rotameter (e.g., 0-15 SCFH recommended). The aeration gas
will rise through the benchtop bioreactor, dissolving oxygen into
the mixture in the process. The aeration gas must provide
sufficient agitation to keep the solids in suspension. Provide an
exit for the aeration gas from the top flange of the benchtop
bioreactor through a water-cooled (e.g., Allihn-type)
vertical condenser. Install the condenser through a gas-tight
fitting in the benchtop bioreactor closure. Install a splitter
which directs a portion of the gas to an exit vent and the rest of
the gas through an air recycle pump back to the benchtop
bioreactor. Monitor and record the flow rate through the exit vent
at least 3 times per day throughout the day.
6.3 Wastewater Feed. Supply the wastewater feed to the benchtop
bioreactor in a collapsible low-density polyethylene container or
collapsible liner in a container (e.g., 20 L) equipped with
a spigot cap (collapsible containers or liners of other material
may be required due to the permeability of some volatile compounds
through polyethylene). Obtain the wastewater feed by sampling the
wastewater feed in the target process. A representative sample of
wastewater shall be obtained from the piping leading to the
aeration tank. This sample may be obtained from existing sampling
valves at the discharge of the wastewater feed pump, or collected
from a pipe discharging to the aeration tank, or by pumping from a
well-mixed equalization tank upstream from the aeration tank.
Alternatively, wastewater can be pumped continuously to the
laboratory apparatus from a bleed stream taken from the
equalization tank of the full-scale treatment system.
6.3.1 Refrigeration System. Keep the wastewater feed cool by ice
or by refrigeration to 4 °C. If using a bleed stream from the
equalization tank, refrigeration is not required if the residence
time in the bleed stream is less than five minutes.
6.3.2 Wastewater Feed Pump. The wastewater is pumped from the
refrigerated container using a variable-speed peristaltic pump
drive equipped with a peristaltic pump head. Add the feed solution
to the benchtop bioreactor through a fitting on the top flange.
Determine the rate of feed addition to provide a retention time in
the benchtop bioreactor that is numerically equivalent to the
retention time in the full-scale system. The wastewater shall be
fed at a rate sufficient to achieve 90 to 100 percent of the
full-scale system residence time.
6.3.3 Treated wastewater feed. The benchtop bioreactor effluent
exits at the bottom of the reactor through a tube and proceeds to
the clarifier.
6.4 Clarifier. The effluent flows to a separate closed clarifier
that allows separation of biomass and effluent (e.g.,
2-liter pear-shaped glass separatory funnel, modified by removing
the stopcock and adding a 25-mm OD glass tube at the bottom).
Benchtop bioreactor effluent enters the clarifier through a tube
inserted to a depth of 0.08 m (3 in.) through a stopper at the top
of the clarifier. System effluent flows from a tube inserted
through the stopper at the top of the clarifier to a drain (or
sample bottle when sampling). The underflow from the clarifier
leaves from the glass tube at the bottom of the clarifier. Flexible
tubing connects this fitting to the sludge recycle pump. This pump
is coupled to a variable speed pump drive. The discharge from this
pump is returned through a tube inserted in a port on the side of
the benchtop bioreactor. An additional port is provided near the
bottom of the benchtop bioreactor for sampling the reactor
contents. The mixed liquor from the benchtop bioreactor flows into
the center of the clarifier. The clarified system effluent
separates from the biomass and flows through an exit near the top
of the clarifier. There shall be no headspace in the clarifier.
6.5 Temperature Control Apparatus. Capable of maintaining the
system at a temperature equal to the temperature of the full-scale
system. The average temperature should be maintained within ±2 °C
of the set point.
6.5.1 Temperature Monitoring Device. A resistance type
temperature probe or a thermocouple connected to a temperature
readout with a resolution of 0.1 °C or better.
6.5.2 Benchtop Bioreactor Heater. The heater is connected to the
temperature control device.
6.6 Oxygen Control System. Maintain the dissolved oxygen
concentration at the levels present in the full-scale system.
Target full-scale activated sludge systems with dissolved oxygen
concentration below 2 mg/L are required to maintain the dissolved
oxygen concentration in the benchtop ioreactor within 0.5 mg/L of
the target dissolved oxygen level. Target full-scale activated
sludge systems with dissolved oxygen concentration above 2 mg/L are
required to maintain the dissolved oxygen concentration in the
benchtop bioreactor within 1.5 mg/L of the target dissolved oxygen
concentration; however, for target full-scale activated sludge
systems with dissolved oxygen concentrations above 2 mg/L, the
dissolved oxygen concentration in the benchtop bioreactor may not
drop below 1.5 mg/L. If the benchtop bioreactor is outside the
control range, the dissolved oxygen is noted and the reactor
operation is adjusted.
6.6.1 Dissolved Oxygen Monitor. Dissolved oxygen is monitored
with a polarographic probe (gas permeable membrane) connected to a
dissolved oxygen meter (e.g., 0 to 15 mg/L, 0 to 50 °C).
6.6.2 Benchtop Bioreactor Pressure Monitor. The benchtop
bioreactor pressure is monitored through a port in the top flange
of the reactor. This is connected to a gauge control with a span of
13-cm water vacuum to 13-cm water pressure or better. A relay is
activated when the vacuum exceeds an adjustable setpoint which
opens a solenoid valve (normally closed), admitting oxygen to the
system. The vacuum setpoint controlling oxygen addition to the
system shall be set at approximately 2.5 ±0.5 cm water and
maintained at this setting except during brief periods when the
dissolved oxygen concentration is adjusted.
6.7 Connecting Tubing. All connecting tubing shall be Teflon or
equivalent in impermeability. The only exception to this
specification is the tubing directly inside the pump head of the
wastewater feed pump, which may be Viton, Silicone or another type
of flexible tubing.
Note:
Mention of trade names or products does not constitute
endorsement by the U.S. Environmental Protection Agency.
7.0 Reagents and Standards
7.1 Wastewater. Obtain a representative sample of wastewater at
the inlet to the full-scale treatment plant if there is an existing
full-scale treatment plant (see section 6.3). If there is no
existing full-scale treatment plant, obtain the wastewater sample
as close to the point of determination as possible. Collect the
sample by pumping the wastewater into the 20-L collapsible
container. The loss of volatiles shall be minimized from the
wastewater by collapsing the container before filling, by
minimizing the time of filling, and by avoiding a headspace in the
container after filling. If the wastewater requires the addition of
nutrients to support the biomass growth and maintain biomass
characteristics, those nutrients are added and mixed with the
container contents after the container is filled.
7.2 Biomass. Obtain the biomass or activated sludge used for
rate constant determination in the bench-scale process from the
existing full-scale process or from a representative biomass
culture (e.g., biomass that has been developed for a future
full-scale process). This biomass is preferentially obtained from a
thickened acclimated mixed liquor sample. Collect the sample either
by bailing from the mixed liquor in the aeration tank with a
weighted container, or by collecting aeration tank effluent at the
effluent overflow weir. Transport the sample to the laboratory
within no more than 4 hours of collection. Maintain the biomass
concentration in the benchtop bioreactor at the level of the
full-scale system + 10 percent throughout the sampling period of
the test method.
8.0 Sample Collection, Preservation, Storage, and Transport
8.1 Benchtop Bioreactor Operation. Charge the mixed liquor to
the benchtop bioreactor, minimizing headspace over the liquid
surface to minimize entrainment of mixed liquor in the circulating
gas. Fasten the benchtop bioreactor headplate to the reactor over
the liquid surface. Maintain the temperature of the contents of the
benchtop bioreactor system at the temperature of the target
full-scale system, ±2 °C, throughout the testing period. Monitor
and record the temperature of the benchtop bioreactor contents at
least to the nearest 0.1 °C.
8.1.1 Wastewater Storage. Collect the wastewater sample in the
20-L collapsible container. Store the container at 4 °C throughout
the testing period. Connect the container to the benchtop
bioreactor feed pump.
8.1.2 Wastewater Flow Rate.
8.1.2.1 The hydraulic residence time of the aeration tank is
calculated as the ratio of the volume of the tank (L) to the flow
rate (L/min). At the beginning of a test, the container shall be
connected to the feed pump and solution shall be pumped to the
benchtop bioreactor at the required flow rate to achieve the
calculated hydraulic residence time of wastewater in the aeration
tank.
![]()
Where: Qtest = wastewater flow rate (L/min) Qfs
= average flow rate of full-scale process (L/min) Vfs = volume of
full-scale aeration tank (L)
8.1.2.2 The target flow rate in the test apparatus is the same
as the flow rate in the target full-scale process multiplied by the
ratio of benchtop bioreactor volume (e.g., 6 L) to the volume of
the full-scale aeration tank. The hydraulic residence time shall be
maintained at 90 to 100 percent of the residence time maintained in
the full-scale unit. A nominal flow rate is set on the pump based
on a pump calibration. Changes in the elasticity of the tubing in
the pump head and the accumulation of material in the tubing affect
this calibration. The nominal pumping rate shall be changed as
necessary based on volumetric flow measurements. Discharge the
benchtop bioreactor effluent to a wastewater storage, treatment, or
disposal facility, except during sampling or flow measurement
periods.
8.1.3 Sludge Recycle Rate. Set the sludge recycle rate at a rate
sufficient to prevent accumulation in the bottom of the clarifier.
Set the air circulation rate sufficient to maintain the biomass in
suspension.
8.1.4 Benchtop Bioreactor Operation and Maintenance.
Temperature, dissolved oxygen concentration, exit vent flow rate,
benchtop bioreactor effluent flow rate, and air circulation rate
shall be measured and recorded three times throughout each day of
benchtop bioreactor operation. If other parameters (such as pH) are
measured and maintained in the target full-scale unit, these
parameters, where appropriate, shall be monitored and maintained to
target full-scale specifications in the benchtop bioreactor. At the
beginning of each sampling period (Section 8.2), sample the
benchtop bioreactor contents for suspended solids analysis. Take
this sample by loosening a clamp on a length of tubing attached to
the lower side port. Determine the suspended solids gravimetrically
by the Gooch crucible/glass fiber filter method for total suspended
solids, in accordance with Standard Methods 3 or equivalent. When
necessary, sludge shall be wasted from the lower side port of the
benchtop bioreactor, and the volume that is wasted shall be
replaced with an equal volume of the reactor effluent. Add
thickened activated sludge mixed liquor as necessary to the
benchtop bioreactor to increase the suspended solids concentration
to the desired level. Pump this mixed liquor to the benchtop
bioreactor through the upper side port (Item 24 in Figure 304A-1).
Change the membrane on the dissolved oxygen probe before starting
the test. Calibrate the oxygen probe immediately before the start
of the test and each time the membrane is changed.
8.1.5 Inspection and Correction Procedures. If the feed line
tubing becomes clogged, replace with new tubing. If the feed flow
rate is not within 5 percent of target flow any time the flow rate
is measured, reset pump or check the flow measuring device and
measure flow rate again until target flow rate is achieved.
8.2 Test Sampling. At least two and one half hydraulic residence
times after the system has reached the targeted specifications
shall be permitted to elapse before the first sample is taken.
Effluent samples of the clarifier discharge (Item 20 in Figure
304A-1) and the influent wastewater feed are collected in 40-mL
septum vials to which two drops of 1:10 hydrochloric acid (HCl) in
water have been added. Sample the clarifier discharge directly from
the drain line. These samples will be composed of the entire flow
from the system for a period of several minutes. Feed samples shall
be taken from the feed pump suction line after temporarily stopping
the benchtop bioreactor feed, removing a connector, and squeezing
the collapsible feed container. Store both influent and effluent
samples at 4 °C immediately after collection and analyze within 8
hours of collection.
8.2.1 Frequency of Sampling. During the test, sample and analyze
the wastewater feed and the clarifier effluent at least six times.
The sampling intervals shall be separated by at least 8 hours.
During any individual sampling interval, sample the wastewater feed
simultaneously with or immediately after the effluent sample.
Calculate the relative standard deviation (RSD) of the amount
removed (i.e., effluent concentration - wastewater feed
concentration). The RSD values shall be <15 percent. If an RSD
value is >15 percent, continue sampling and analyzing influent
and effluent sets of samples until the RSD values are within
specifications.
8.2.2 Sampling After Exposure of System to Atmosphere. If, after
starting sampling procedures, the benchtop bioreactor system is
exposed to the atmosphere (due to leaks, maintenance, etc.), allow
at least one hydraulic residence time to elapse before resuming
sampling.
9.0 Quality Control
9.1 Dissolved Oxygen. Fluctuation in dissolved oxygen
concentration may occur for numerous reasons, including undetected
gas leaks, increases and decreases in mixed liquor suspended solids
resulting from cell growth and solids loss in the effluent stream,
changes in diffuser performance, cycling of effluent flow rate, and
overcorrection due to faulty or sluggish dissolved oxygen probe
response. Control the dissolved oxygen concentration in the
benchtop bioreactor by changing the proportion of oxygen in the
circulating aeration gas. Should the dissolved oxygen concentration
drift below the designated experimental condition, bleed a small
amount of aeration gas from the system on the pressure side (i.e.,
immediately upstream of one of the diffusers). This will create a
vacuum in the system, triggering the pressure sensitive relay to
open the solenoid valve and admit oxygen to the system. Should the
dissolved oxygen concentration drift above the designated
experimental condition, slow or stop the oxygen input to the system
until the dissolved oxygen concentration approaches the correct
level.
9.2 Sludge Wasting.
9.2.1 Determine the suspended solids concentration (section
8.1.4) at the beginning of a test, and once per day thereafter
during the test. If the test is completed within a two day period,
determine the suspended solids concentration after the final sample
set is taken. If the suspended solids concentration exceeds the
specified concentration, remove a fraction of the sludge from the
benchtop bioreactor. The required volume of mixed liquor to remove
is determined as follows:

Where: Vw
is the wasted volume (Liters), Vr is the volume of the benchtop
bioreactor (Liters), Sm is the measured solids (g/L), and Ss is the
specified solids (g/L).
9.2.2 Remove the mixed liquor from the benchtop bioreactor by
loosening a clamp on the mixed liquor sampling tube and allowing
the required volume to drain to a graduated flask. Clamp the tube
when the correct volume has been wasted. Replace the volume of the
liquid wasted by pouring the same volume of effluent back into the
benchtop bioreactor. Dispose of the waste sludge properly.
9.3 Sludge Makeup. In the event that the suspended solids
concentration is lower than the specifications, add makeup sludge
back into the benchtop bioreactor. Determine the amount of sludge
added by the following equation:

Where: Vw
is the volume of sludge to add (Liters), Vr is the volume of the
benchtop bioreactor (Liters), Sw is the solids in the makeup sludge
(g/L), Sm is the measured solids (g/L), and Ss is the specified
solids (g/L). 10.0 Calibration and Standardization
10.1 Wastewater Pump Calibration. Determine the wastewater flow
rate by collecting the system effluent for a time period of at
least one hour, and measuring the volume with a graduated cylinder.
Record the collection time period and volume collected. Determine
flow rate. Adjust the pump speed to deliver the specified flow
rate.
10.2 Calibration Standards. Prepare calibration standards from
pure certified standards in an aqueous medium. Prepare and analyze
three concentrations of calibration standards for each target
component (or for a mixture of components) in triplicate daily
throughout the analyses of the test samples. At each concentration
level, a single calibration shall be within 5 percent of the
average of the three calibration results. The low and medium
calibration standards shall bracket the expected concentration of
the effluent (treated) wastewater. The medium and high standards
shall bracket the expected influent concentration.
11.0 Analytical Procedures
11.1 Analysis. If the identity of the compounds of interest in
the wastewater is not known, a representative sample of the
wastewater shall be analyzed in order to identify all of the
compounds of interest present. A gas chromatography/mass
spectrometry screening method is recommended.
11.1.1 After identifying the compounds of interest in the
wastewater, develop and/or use one or more analytical techniques
capable of measuring each of those compounds (more than one
analytical technique may be required, depending on the
characteristics of the wastewater). Test Method 18, found in
appendix A of 40 CFR 60, may be used as a guideline in developing
the analytical technique. Purge and trap techniques may be used for
analysis providing the target components are sufficiently volatile
to make this technique appropriate. The limit of quantitation for
each compound shall be determined (see reference 1). If the
effluent concentration of any target compound is below the limit of
quantitation determined for that compound, the operation of the
Method 304 unit may be altered to attempt to increase the effluent
concentration above the limit of quantitation. Modifications to the
method shall be approved prior to the test. The request should be
addressed to Method 304 contact, Emissions Measurement Center, Mail
Drop 19, U.S. Environmental Protection Agency, Research Triangle
Park, NC 27711.
12.0 Data Analysis and Calculations
12.1 Nomenclature. The following symbols are used in the
calculations.
Ci = Average inlet feed concentration for a compound of interest,
as analyzed (mg/L) Co = Average outlet (effluent) concentration for
a compound of interest, as analyzed (mg/L) X = Biomass
concentration, mixed liquor suspended solids (g/L) t = Hydraulic
residence time in the benchtop bioreactor (hours) V = Volume of the
benchtop bioreactor (L) Q = Flow rate of wastewater into the
benchtop bioreactor, average (L/hour)
12.2 Residence Time. The hydraulic residence time of the
benchtop bioreactor is equal to the ratio of the volume of the
benchtop bioreactor (L) to the flow rate (L/h):
12.3 Rate of Biodegradation. Calculate the rate of
biodegradation for each component with the following equation:
12.4 First-Order Biorate Constant. Calculate the first-order
biorate constant (K1) for each component with the following
equation:
12.5 Relative Standard Deviation (RSD). Determine the standard
deviation of both the influent and effluent sample concentrations
(S) using the following equation:
12.6 Determination of Percent Air Emissions and Percent
Biodegraded. Use the results from this test method and follow the
applicable procedures in appendix C of 40 CFR part 63, entitled,
“Determination of the Fraction Biodegraded (Fbio) in a Biological
Treatment Unit” to determine Fbio.
13.0 Method Performance [Reserved] 14.0 Pollution Prevention
[Reserved] 15.0 Waste Management [Reserved] 16.0 References
1. “Guidelines for data acquisition and data quality evaluation
in Environmental Chemistry,” Daniel MacDoughal, Analytical
Chemistry, Volume 52, p. 2242, 1980.
2. Test Method 18, 40 CFR 60, appendix A.
3. Standard Methods for the Examination of Water and Wastewater,
16th Edition, Method 209C, Total Suspended Solids Dried at 103-105
°C, APHA, 1985.
4. Water7, Hazardous Waste Treatment, Storage, and Disposal
Facilities (TSDF) - Air Emission Models, U.S. Environmental
Protection Agency, EPA-450/3-87-026, Review Draft, November
1989.
5. Chemdat7, Hazardous Waste Treatment, Storage, and Disposal
Facilities (TSDF) - Air Emission Models, U.S. Environmental
Protection Agency, EPA-450/3-87-026, Review Draft, November
1989.
17.0 Tables, Diagrams, Flowcharts, and Validation Data

Method 304B:
Determination of Biodegradation Rates of Organic Compounds
(Scrubber Option) 1.0 Scope and Application
1.1 Applicability. This method is applicable for the
determination of biodegradation rates of organic compounds in an
activated sludge process. The test method is designed to evaluate
the ability of an aerobic biological reaction system to degrade or
destroy specific components in waste streams. The method may also
be used to determine the effects of changes in wastewater
composition on operation. The biodegradation rates determined by
utilizing this method are not representative of a full-scale
system. Full-scale systems embody biodegradation and air emissions
in competing reactions. This method measures biodegradation in
absence of air emissions. The rates measured by this method shall
be used in conjunction with the procedures listed in appendix C of
this part to calculate the fraction emitted to the air versus the
fraction biodegraded.
2.0 Summary of Method
2.1 A self-contained benchtop bioreactor system is assembled in
the laboratory. A sample of mixed liquor is added and the waste
stream is then fed continuously. The benchtop bioreactor is
operated under conditions nearly identical to the target full-scale
activated sludge process, except that air emissions are not a
factor. The benchtop bioreactor temperature, dissolved oxygen
concentration, average residence time in the reactor, waste
composition, biomass concentration, and biomass composition of the
target full-scale process are the parameters which are duplicated
in the laboratory system. Biomass shall be removed from the target
full-scale activated sludge unit and held for no more than 4 hours
prior to use in the benchtop bioreactor. If antifoaming agents are
used in the full-scale system, they shall also be used in the
benchtop bioreactor. The feed flowing into and the effluent exiting
the benchtop bioreactor are analyzed to determine the
biodegradation rates of the target compounds. The choice of
analytical methodology for measuring the compounds of interest at
the inlet and outlet to the benchtop bioreactor are left to the
discretion of the source, except where validated methods are
available.
3.0 Definitions [Reserved] 4.0 Interferences [Reserved] 5.0 Safety
5.1 If explosive gases are produced as a byproduct of
biodegradation and could realistically pose a hazard, closely
monitor headspace concentration of these gases to ensure laboratory
safety. Placement of the benchtop bioreactor system inside a
laboratory hood is recommended regardless of byproducts
produced.
6.0 Equipment and Supplies Note:
Figure 304B-1 illustrates a typical laboratory apparatus used to
measure biodegradation rates. While the following description
refers to Figure 304B-1, the EPA recognizes that alternative
reactor configurations, such as alternative reactor shapes and
locations of probes and the feed inlet, will also meet the intent
of this method. Ensure that the benchtop bioreactor system is
self-contained and isolated from the atmosphere by leak-checking
fittings, tubing, etc.
6.1 Benchtop Bioreactor. The biological reaction is conducted in
a biological oxidation reactor of at least 6-liters capacity. The
benchtop bioreactor is sealed and equipped with internal probes for
controlling and monitoring dissolved oxygen and internal
temperature. The top of the benchtop bioreactor is equipped for
aerators, gas flow ports, and instrumentation (while ensuring that
no leaks to the atmosphere exist around the fittings).
6.2 Aeration gas. Aeration gas is added to the benchtop
bioreactor through three diffusers, which are glass tubes that
extend to the bottom fifth of the reactor depth. A pure oxygen
pressurized cylinder is recommended in order to maintain the
specified oxygen concentration. Install a blower (e.g.,
Diaphragm Type, 15 SCFH capacity) to blow the aeration gas into the
benchtop bioreactor diffusers. Measure the aeration gas flow rate
with a rotameter (e.g., 0-15 SCFH recommended). The aeration
gas will rise through the benchtop bioreactor, dissolving oxygen
into the mixture in the process. The aeration gas must provide
sufficient agitation to keep the solids in suspension. Provide an
exit for the aeration gas from the top flange of the benchtop
bioreactor through a water-cooled (e.g., Allihn-type)
vertical condenser. Install the condenser through a gas-tight
fitting in the benchtop bioreactor closure. Design the system so
that at least 10 percent of the gas flows through an alkaline
scrubber containing 175 mL of 45 percent by weight solution of
potassium hydroxide (KOH) and 5 drops of 0.2 percent alizarin
yellow dye. Route the balance of the gas through an adjustable
scrubber bypass. Route all of the gas through a 1-L knock-out flask
to remove entrained moisture and then to the intake of the blower.
The blower recirculates the gas to the benchtop bioreactor.
6.3 Wastewater Feed. Supply the wastewater feed to the benchtop
bioreactor in a collapsible low-density polyethylene container or
collapsible liner in a container (e.g., 20 L) equipped with
a spigot cap (collapsible containers or liners of other material
may be required due to the permeability of some volatile compounds
through polyethylene). Obtain the wastewater feed by sampling the
wastewater feed in the target process. A representative sample of
wastewater shall be obtained from the piping leading to the
aeration tank. This sample may be obtained from existing sampling
valves at the discharge of the wastewater feed pump, or collected
from a pipe discharging to the aeration tank, or by pumping from a
well-mixed equalization tank upstream from the aeration tank.
Alternatively, wastewater can be pumped continuously to the
laboratory apparatus from a bleed stream taken from the
equalization tank of the full-scale treatment system.
6.3.1 Refrigeration System. Keep the wastewater feed cool by ice
or by refrigeration to 4 °C. If using a bleed stream from the
equalization tank, refrigeration is not required if the residence
time in the bleed stream is less than five minutes.
6.3.2 Wastewater Feed Pump. The wastewater is pumped from the
refrigerated container using a variable-speed peristaltic pump
drive equipped with a peristaltic pump head. Add the feed solution
to the benchtop bioreactor through a fitting on the top flange.
Determine the rate of feed addition to provide a retention time in
the benchtop bioreactor that is numerically equivalent to the
retention time in the target full-scale system. The wastewater
shall be fed at a rate sufficient to achieve 90 to 100 percent of
the target full-scale system residence time.
6.3.3 Treated wastewater feed. The benchtop bioreactor effluent
exits at the bottom of the reactor through a tube and proceeds to
the clarifier.
6.4 Clarifier. The effluent flows to a separate closed clarifier
that allows separation of biomass and effluent (e.g.,
2-liter pear-shaped glass separatory funnel, modified by removing
the stopcock and adding a 25-mm OD glass tube at the bottom).
Benchtop bioreactor effluent enters the clarifier through a tube
inserted to a depth of 0.08 m (3 in.) through a stopper at the top
of the clarifier. System effluent flows from a tube inserted
through the stopper at the top of the clarifier to a drain (or
sample bottle when sampling). The underflow from the clarifier
leaves from the glass tube at the bottom of the clarifier. Flexible
tubing connects this fitting to the sludge recycle pump. This pump
is coupled to a variable speed pump drive. The discharge from this
pump is returned through a tube inserted in a port on the side of
the benchtop bioreactor. An additional port is provided near the
bottom of the benchtop bioreactor for sampling the reactor
contents. The mixed liquor from the benchtop bioreactor flows into
the center of the clarifier. The clarified system effluent
separates from the biomass and flows through an exit near the top
of the clarifier. There shall be no headspace in the clarifier.
6.5 Temperature Control Apparatus. Capable of maintaining the
system at a temperature equal to the temperature of the full-scale
system. The average temperature should be maintained within ±2 °C
of the set point.
6.5.1 Temperature Monitoring Device. A resistance type
temperature probe or a thermocouple connected to a temperature
readout with a resolution of 0.1 °C or better.
6.5.2 Benchtop Bioreactor Heater. The heater is connected to the
temperature control device.
6.6 Oxygen Control System. Maintain the dissolved oxygen
concentration at the levels present in the full-scale system.
Target full-scale activated sludge systems with dissolved oxygen
concentration below 2 mg/L are required to maintain the dissolved
oxygen concentration in the benchtop bioreactor within 0.5 mg/L of
the target dissolved oxygen level. Target full-scale activated
sludge systems with dissolved oxygen concentration above 2 mg/L are
required to maintain the dissolved oxygen concentration in the
benchtop bioreactor within 1.5 mg/L of the target dissolved oxygen
concentration; however, for target full-scale activated sludge
systems with dissolved oxygen concentrations above 2 mg/L, the
dissolved oxygen concentration in the benchtop bioreactor may not
drop below 1.5 mg/L. If the benchtop bioreactor is outside the
control range, the dissolved oxygen is noted and the reactor
operation is adjusted.
6.6.1 Dissolved Oxygen Monitor. Dissolved oxygen is monitored
with a polarographic probe (gas permeable membrane) connected to a
dissolved oxygen meter (e.g., 0 to 15 mg/L, 0 to 50 °C).
6.6.2 Benchtop Bioreactor Pressure Monitor. The benchtop
bioreactor pressure is monitored through a port in the top flange
of the reactor. This is connected to a gauge control with a span of
13-cm water vacuum to 13-cm water pressure or better. A relay is
activated when the vacuum exceeds an adjustable setpoint which
opens a solenoid valve (normally closed), admitting oxygen to the
system. The vacuum setpoint controlling oxygen addition to the
system shall be set at approximately 2.5 ±0.5 cm water and
maintained at this setting except during brief periods when the
dissolved oxygen concentration is adjusted.
6.7 Connecting Tubing. All connecting tubing shall be Teflon or
equivalent in impermeability. The only exception to this
specification is the tubing directly inside the pump head of the
wastewater feed pump, which may be Viton, Silicone or another type
of flexible tubing.
Note:
Mention of trade names or products does not constitute
endorsement by the U.S. Environmental Protection Agency.
7.0. Reagents and Standards
7.1 Wastewater. Obtain a representative sample of wastewater at
the inlet to the full-scale treatment plant if there is an existing
full-scale treatment plant (See Section 6.3). If there is no
existing full-scale treatment plant, obtain the wastewater sample
as close to the point of determination as possible. Collect the
sample by pumping the wastewater into the 20-L collapsible
container. The loss of volatiles shall be minimized from the
wastewater by collapsing the container before filling, by
minimizing the time of filling, and by avoiding a headspace in the
container after filling. If the wastewater requires the addition of
nutrients to support the biomass growth and maintain biomass
characteristics, those nutrients are added and mixed with the
container contents after the container is filled.
7.2 Biomass. Obtain the biomass or activated sludge used for
rate constant determination in the bench-scale process from the
existing full-scale process or from a representative biomass
culture (e.g., biomass that has been developed for a future
full-scale process). This biomass is preferentially obtained from a
thickened acclimated mixed liquor sample. Collect the sample either
by bailing from the mixed liquor in the aeration tank with a
weighted container, or by collecting aeration tank effluent at the
effluent overflow weir. Transport the sample to the laboratory
within no more than 4 hours of collection. Maintain the biomass
concentration in the benchtop bioreactor at the level of the target
full-scale system + 10 percent throughout the sampling period of
the test method.
8.0 Sample Collection, Preservation, Storage, and Transport
8.1 Benchtop Bioreactor Operation. Charge the mixed liquor to
the benchtop bioreactor, minimizing headspace over the liquid
surface to minimize entrainment of mixed liquor in the circulating
gas. Fasten the benchtop bioreactor headplate to the reactor over
the liquid surface. Maintain the temperature of the contents of the
benchtop bioreactor system at the temperature of the target
full-scale system, ±2 °C, throughout the testing period. Monitor
and record the temperature of the reactor contents at least to the
nearest 0.1 °C.
8.1.1 Wastewater Storage. Collect the wastewater sample in the
20-L collapsible container. Store the container at 4 °C throughout
the testing period. Connect the container to the benchtop
bioreactor feed pump.
8.1.2 Wastewater Flow Rate.
8.1.2.1 The hydraulic residence time of the aeration tank is
calculated as the ratio of the volume of the tank (L) to the flow
rate (L/min). At the beginning of a test, the container shall be
connected to the feed pump and solution shall be pumped to the
benchtop bioreactor at the required flow rate to achieve the
calculated hydraulic residence time of wastewater in the aeration
tank.
![]()
Where: Qtest = wastewater flow rate (L/min) Qfs
= average flow rate of full-scale process (L/min) Vfs = volume of
full-scale aeration tank (L)
8.1.2.2 The target flow rate in the test apparatus is the same
as the flow rate in the target full-scale process multiplied by the
ratio of benchtop bioreactor volume (e.g., 6 L) to the
volume of the full-scale aeration tank. The hydraulic residence
time shall be maintained at 90 to 100 percent of the residence time
maintained in the target full-scale unit. A nominal flow rate is
set on the pump based on a pump calibration. Changes in the
elasticity of the tubing in the pump head and the accumulation of
material in the tubing affect this calibration. The nominal pumping
rate shall be changed as necessary based on volumetric flow
measurements. Discharge the benchtop bioreactor effluent to a
wastewater storage, treatment, or disposal facility, except during
sampling or flow measurement periods.
8.1.3 Sludge Recycle Rate. Set the sludge recycle rate at a rate
sufficient to prevent accumulation in the bottom of the clarifier.
Set the air circulation rate sufficient to maintain the biomass in
suspension.
8.1.4 Benchtop Bioreactor Operation and Maintenance.
Temperature, dissolved oxygen concentration, flow rate, and air
circulation rate shall be measured and recorded three times
throughout each day of testing. If other parameters (such as pH)
are measured and maintained in the target full-scale unit, these
parameters shall, where appropriate, be monitored and maintained to
full-scale specifications in the benchtop bioreactor. At the
beginning of each sampling period (section 8.2), sample the
benchtop bioreactor contents for suspended solids analysis. Take
this sample by loosening a clamp on a length of tubing attached to
the lower side port. Determine the suspended solids gravimetrically
by the Gooch crucible/glass fiber filter method for total suspended
solids, in accordance with Standard Methods 3 or equivalent. When
necessary, sludge shall be wasted from the lower side port of the
benchtop bioreactor, and the volume that is wasted shall be
replaced with an equal volume of the benchtop bioreactor effluent.
Add thickened activated sludge mixed liquor as necessary to the
benchtop bioreactor to increase the suspended solids concentration
to the desired level. Pump this mixed liquor to the benchtop
bioreactor through the upper side port (Item 24 in Figure 304B-1).
Change the membrane on the dissolved oxygen probe before starting
the test. Calibrate the oxygen probe immediately before the start
of the test and each time the membrane is changed. The scrubber
solution shall be replaced each weekday with 175 mL 45 percent W/W
KOH solution to which five drops of 0.2 percent alizarin yellow
indicator in water have been added. The potassium hydroxide
solution in the alkaline scrubber shall be changed if the alizarin
yellow dye color changes.
8.1.5 Inspection and Correction Procedures. If the feed line
tubing becomes clogged, replace with new tubing. If the feed flow
rate is not within 5 percent of target flow any time the flow rate
is measured, reset pump or check the flow measuring device and
measure flow rate again until target flow rate is achieved.
8.2 Test Sampling. At least two and one half hydraulic residence
times after the system has reached the targeted specifications
shall be permitted to elapse before the first sample is taken.
Effluent samples of the clarifier discharge (Item 20 in Figure
304B-1) and the influent wastewater feed are collected in 40-mL
septum vials to which two drops of 1:10 hydrochloric acid (HCl) in
water have been added. Sample the clarifier discharge directly from
the drain line. These samples will be composed of the entire flow
from the system for a period of several minutes. Feed samples shall
be taken from the feed pump suction line after temporarily stopping
the benchtop bioreactor feed, removing a connector, and squeezing
the collapsible feed container. Store both influent and effluent
samples at 4 °C immediately after collection and analyze within 8
hours of collection.
8.2.1 Frequency of Sampling. During the test, sample and analyze
the wastewater feed and the clarifier effluent at least six times.
The sampling intervals shall be separated by at least 8 hours.
During any individual sampling interval, sample the wastewater feed
simultaneously with or immediately after the effluent sample.
Calculate the RSD of the amount removed (i.e., effluent
concentration - wastewater feed concentration). The RSD values
shall be <15 percent. If an RSD value is >15 percent,
continue sampling and analyzing influent and effluent sets of
samples until the RSD values are within specifications.
8.2.2 Sampling After Exposure of System to Atmosphere. If, after
starting sampling procedures, the benchtop bioreactor system is
exposed to the atmosphere (due to leaks, maintenance, etc.), allow
at least one hydraulic residence time to elapse before resuming
sampling.
9.0 Quality Control
9.1 Dissolved Oxygen. Fluctuation in dissolved oxygen
concentration may occur for numerous reasons, including undetected
gas leaks, increases and decreases in mixed liquor suspended solids
resulting from cell growth and solids loss in the effluent stream,
changes in diffuser performance, cycling of effluent flow rate, and
overcorrection due to faulty or sluggish dissolved oxygen probe
response. Control the dissolved oxygen concentration in the
benchtop bioreactor by changing the proportion of oxygen in the
circulating aeration gas. Should the dissolved oxygen concentration
drift below the designated experimental condition, bleed a small
amount of aeration gas from the system on the pressure side
(i.e., immediately upstream of one of the diffusers). This
will create a vacuum in the system, triggering the pressure
sensitive relay to open the solenoid valve and admit oxygen to the
system. Should the dissolved oxygen concentration drift above the
designated experimental condition, slow or stop the oxygen input to
the system until the dissolved oxygen concentration approaches the
correct level.
9.2 Sludge Wasting.
9.2.1 Determine the suspended solids concentration (section
8.1.4) at the beginning of a test, and once per day thereafter
during the test. If the test is completed within a two day period,
determine the suspended solids concentration after the final sample
set is taken. If the suspended solids concentration exceeds the
specified concentration, remove a fraction of the sludge from the
benchtop bioreactor. The required volume of mixed liquor to remove
is determined as follows:

Where: Vw
is the wasted volume (Liters), Vr is the volume of the benchtop
bioreactor (Liters), Sm is the measured solids (g/L), and Ss is the
specified solids (g/L).
9.2.2 Remove the mixed liquor from the benchtop bioreactor by
loosening a clamp on the mixed liquor sampling tube and allowing
the required volume to drain to a graduated flask. Clamp the tube
when the correct volume has been wasted. Replace the volume of the
liquid wasted by pouring the same volume of effluent back into the
benchtop bioreactor. Dispose of the waste sludge properly.
9.3 Sludge Makeup. In the event that the suspended solids
concentration is lower than the specifications, add makeup sludge
back into the benchtop bioreactor. Determine the amount of sludge
added by the following equation:
![]()
Where: Vw is the volume of sludge to add
(Liters), Vr is the volume of the benchtop bioreactor (Liters), Sw
is the solids in the makeup sludge (g/L), Sm is the measured solids
(g/L), and Ss is the specified solids (g/L). 10.0 Calibration and
Standardizations
10.1 Wastewater Pump Calibration. Determine the wastewater flow
rate by collecting the system effluent for a time period of at
least one hour, and measuring the volume with a graduated cylinder.
Record the collection time period and volume collected. Determine
flow rate. Adjust the pump speed to deliver the specified flow
rate.
10.2 Calibration Standards. Prepare calibration standards from
pure certified standards in an aqueous medium. Prepare and analyze
three concentrations of calibration standards for each target
component (or for a mixture of components) in triplicate daily
throughout the analyses of the test samples. At each concentration
level, a single calibration shall be within 5 percent of the
average of the three calibration results. The low and medium
calibration standards shall bracket the expected concentration of
the effluent (treated) wastewater. The medium and high standards
shall bracket the expected influent concentration.
11.0 Analytical Test Procedures
11.1 Analysis. If the identity of the compounds of interest in
the wastewater is not known, a representative sample of the
wastewater shall be analyzed in order to identify all of the
compounds of interest present. A gas chromatography/mass
spectrometry screening method is recommended.
11.1.1 After identifying the compounds of interest in the
wastewater, develop and/or use one or more analytical technique
capable of measuring each of those compounds (more than one
analytical technique may be required, depending on the
characteristics of the wastewater). Method 18, found in appendix A
of 40 CFR 60, may be used as a guideline in developing the
analytical technique. Purge and trap techniques may be used for
analysis providing the target components are sufficiently volatile
to make this technique appropriate. The limit of quantitation for
each compound shall be determined. 1 If the effluent concentration
of any target compound is below the limit of quantitation
determined for that compound, the operation of the Method 304 unit
may be altered to attempt to increase the effluent concentration
above the limit of quantitation. Modifications to the method shall
be approved prior to the test. The request should be addressed to
Method 304 contact, Emissions Measurement Center, Mail Drop 19,
U.S. Environmental Protection Agency, Research Triangle Park, NC
27711.
12.0 Data Analysis and Calculations
12.1 Nomenclature. The following symbols are used in the
calculations.
Ci = Average inlet feed concentration for a compound of interest,
as analyzed (mg/L) Co = Average outlet (effluent) concentration for
a compound of interest, as analyzed (mg/L) X = Biomass
concentration, mixed liquor suspended solids (g/L) t = Hydraulic
residence time in the benchtop bioreactor (hours) V = Volume of the
benchtop bioreactor (L) Q = Flow rate of wastewater into the
benchtop bioreactor, average (L/hour)
12.2 Residence Time. The hydraulic residence time of the
benchtop bioreactor is equal to the ratio of the volume of the
benchtop bioreactor (L) to the flow rate (L/h)
12.3 Rate of Biodegradation. Calculate the rate of
biodegradation for each component with the following equation:
12.4 First-Order Biorate Constant. Calculate the first-order
biorate constant (K1) for each component with the following
equation:
12.5 Relative Standard Deviation (RSD). Determine the standard
deviation of both the influent and effluent sample concentrations
(S) using the following equation:
12.6 Determination of Percent Air Emissions and Percent
Biodegraded. Use the results from this test method and follow the
applicable procedures in appendix C of 40 CFR Part 63, entitled,
“Determination of the Fraction Biodegraded (Fbio) in a Biological
Treatment Unit” to determine Fbio.
13.0 Method Performance [Reserved] 14.0 Pollution Prevention
[Reserved] 15.0 Waste Management [Reserved] 16.0 References
1. “Guidelines for data acquisition and data quality evaluation
in Environmental Chemistry”, Daniel MacDoughal, Analytical
Chemistry, Volume 52, p. 2242, 1980.
2. Test Method 18, 40 CFR 60, Appendix A.
3. Standard Methods for the Examination of Water and Wastewater,
16th Edition, Method 209C, Total Suspended Solids Dried at 103-105
°C, APHA, 1985.
4. Water - 7, Hazardous Waste Treatment, Storage, and Disposal
Facilities (TSDF) - Air Emission Models, U.S. Environmental
Protection Agency, EPA-450/3-87-026, Review Draft, November
1989.
5. Chemdat7, Hazardous Waste Treatment, Storage, and Disposal
Facilities (TSDF) - Air Emission Models, U.S. Environmental
Protection Agency, EPA-450/3-87-026, Review Draft, November
1989.
17.0 Tables, Diagrams, Flowcharts, and Validation Data

Method 305:
Measurement of Emission Potential of Individual Volatile Organic
Compounds in Waste Note:
This method does not include all of the specifications
(e.g., equipment and supplies) and procedures (e.g.,
sampling and analytical) essential to its performance. Some
material is incorporated by reference from other methods in 40 CFR
Part 60, Appendix A. Therefore, to obtain reliable results, persons
using this method should have a thorough knowledge of at least
Method 25D.
1.0 Scope and Application
1.1 Analyte. Volatile Organics. No CAS No. assigned.
1.2 Applicability. This procedure is used to determine the
emission potential of individual volatile organics (VOs) in
waste.
1.3 Data Quality Objectives. Adherence to the requirements of
this method will enhance the quality of the data obtained from air
pollutant sampling methods.
2.0 Summary of Method
2.1 The heated purge conditions established by Method 25D (40
CFR Part 60, Appendix A) are used to remove VOs from a 10 gram
sample of waste suspended in a 50/50 solution of polyethylene
glycol (PEG) and water. The purged VOs are quantified by using the
sample collection and analytical techniques (e.g. gas
chromatography) appropriate for the VOs present in the waste. The
recovery efficiency of the sample collection and analytical
technique is determined for each waste matrix. A correction factor
is determined for each compound (if acceptable recovery criteria
requirements are met of 70 to 130 percent recovery for every target
compound), and the measured waste concentration is corrected with
the correction factor for each compound. A minimum of three
replicate waste samples shall be analyzed.
3.0 Definitions [Reserved] 4.0 Interferences [Reserved] 5.0 Safety
5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of
the safety problems associated with its use. It is the
responsibility of the user of this test method to establish
appropriate safety and health practices and to determine the
applicability of regulatory limitations prior to performing this
test method.
6.0 Equipment and Supplies
6.1 Method 25D Purge Apparatus.
6.1.1 Purge Chamber. The purge chamber shall accommodate the 10
gram sample of waste suspended in a matrix of 50 mL of PEG and 50
mL of deionized, hydrocarbon-free water. Three fittings are used on
the glass chamber top. Two #7 Ace-threads are used for the purge
gas inlet and outlet connections. A #50 Ace-thread is used to
connect the top of the chamber to the base (see Figure 305-1). The
base of the chamber has a side-arm equipped with a #22 Sovirel
fitting to allow for easy sample introductions into the chamber.
The dimensions of the chamber are shown in Figure 305-1.
6.1.2 Flow Distribution Device (FDD). The FDD enhances the
gas-to-liquid contact for improved purging efficiency. The FDD is a
6 mm OD (0.2 in) by 30 cm (12 in) long glass tube equipped with
four arm bubblers as shown in Figure 305-1. Each arm shall have an
opening of 1 mm (0.04 in) in diameter.
6.1.3 Coalescing Filter. The coalescing filter serves to
discourage aerosol formation of sample gas once it leaves the purge
chamber. The glass filter has a fritted disc mounted 10 cm (3.9 in)
from the bottom. Two #7 Ace-threads are used for the inlet and
outlet connections. The dimensions of the chamber are shown in
Figure 305-2.
6.1.4 Oven. A forced convection airflow oven capable of
maintaining the purge chamber and coalescing filter at 75 ±2 °C
(167 ±3.6 °F).
6.1.5 Toggle Valve. An on/off valve constructed from brass or
stainless steel rated to 100 psig. This valve is placed in line
between the purge nitrogen source and the flow controller.
6.1.6 Flow Controller. High-quality stainless steel flow
controller capable of restricting a flow of nitrogen to 6 ±0.06
L/min (0.2 ±0.002 ft 3/min) at 40 psig.
6.1.7 Polyethylene Glycol Cleaning System.
6.1.7.1 Round-Bottom Flask. One liter, three-neck glass
round-bottom flask for cleaning PEG. Standard taper 24/40 joints
are mounted on each neck.
6.1.7.2 Heating Mantle. Capable of heating contents of the 1-L
flask to 120 °C (248 °F).
6.1.7.3 Nitrogen Bubbler. Teflon ® or glass tube, 0.25 in OD
(6.35 mm).
6.1.7.4 Temperature Sensor. Partial immersion glass
thermometer.
6.1.7.5 Hose Adapter. Glass with 24/40 standard tapered
joint.
6.2 Volatile Organic Recovery System.
6.2.1 Splitter Valve (Optional). Stainless steel cross-pattern
valve capable of splitting nominal flow rates from the purge flow
of 6 L/min (0.2 ft 3/min). The valve shall be maintained at 75 + 2
°C (167 ±3.6 °F) in the heated zone and shall be placed downstream
of the coalescing filter. It is recommended that 0.125 in OD (3.175
mm) tubing be used to direct the split vent flow from the heated
zone. The back pressure caused by the 0.125 in OD (3.175 mm) tubing
is critical for maintaining proper split valve operation.
Note:
The splitter valve design is optional; it may be used in cases
where the concentration of a pollutant would saturate the
adsorbents.
6.2.2 Injection Port. Stainless steel 1/4 in OD (6.35 mm)
compression fitting tee with a 6 mm (0.2 in) septum fixed on the
top port. The injection port is the point of entry for the recovery
study solution. If using a gaseous standard to determine recovery
efficiency, connect the gaseous standard to the injection port of
the tee.
6.2.3 Knockout Trap (Optional but Recommended). A 25 mL capacity
glass reservoir body with a full-stem impinger (to avoid leaks, a
modified midget glass impinger with a screw cap and ball/socket
clamps on the inlet and outlet is recommended). The empty impinger
is placed in an ice water bath between the injection port and the
sorbent cartridge. Its purpose is to reduce the water content of
the purge gas (saturated at 75 °C (167 °F)) before the sorbent
cartridge.
6.2.4 Insulated Ice Bath. A 350 mL dewar or other type of
insulated bath is used to maintain ice water around the knockout
trap.
6.2.5 Sorbent Cartridges. Commercially available glass or
stainless steel cartridge packed with one or more appropriate
sorbents. The amount of adsorbent packed in the cartridge depends
on the breakthrough volume of the test compounds but is limited by
back pressure caused by the packing (not to exceed 7 psig). More
than one sorbent cartridge placed in series may be necessary
depending upon the mixture of the measured components.
6.2.6 Volumetric Glassware. Type A glass 10 mL volumetric flasks
for measuring a final volume from the water catch in the knockout
trap.
6.2.7 Thermal Desorption Unit. A clam-shell type oven, used for
the desorption of direct thermal desorption sorbent tubes. The oven
shall be capable of increasing the temperature of the desorption
tubes rapidly to recommended desorption temperature.
6.2.8 Ultrasonic Bath. Small bath used to agitate sorbent
material and desorption solvent. Ice water shall be used in the
bath because of heat transfer caused by operation of the bath.
6.2.9 Desorption Vials. Four-dram (15 mL) capacity borosilicate
glass vials with Teflon-lined caps.
6.3 Analytical System. A gas chromatograph (GC) is commonly used
to separate and quantify compounds from the sample collection and
recovery procedure. Method 18 (40 CFR Part 60, Appendix A) may be
used as a guideline for determining the appropriate GC column and
GC detector based on the test compounds to be determined. Other
types of analytical instrumentation may be used (HPLC) in lieu of
GC systems as long as the recovery efficiency criteria of this
method are met.
6.3.1 Gas Chromatograph (GC). The GC shall be equipped with a
constant-temperature liquid injection port or a heated sampling
loop/valve system, as appropriate. The GC oven shall be
temperature-programmable over the useful range of the GC column.
The choice of detectors is based on the test compounds to be
determined.
6.3.2 GC Column. Select the appropriate GC column based on (1)
literature review or previous experience, (2) polarity of the
analytes, (3) capacity of the column, or (4) resolving power
(e.g., length, diameter, film thickness) required.
6.3.3 Data System. A programmable electronic integrator for
recording, analyzing, and storing the signal generated by the
detector.
7.0 Reagents and Standards
7.1 Method 25D Purge Apparatus.
7.1.1 Polyethylene Glycol (PEG). Ninety-eight percent pure
organic polymer with an average molecular weight of 400 g/mol.
Volatile organics are removed from the PEG prior to use by heating
to 120 ±5 °C (248 ±9 °F) and purging with pure nitrogen at 1 L/min
(0.04 ft 3/min) for 2 hours. After purging and heating, the PEG is
maintained at room temperature under a nitrogen purge maintained at
1 L/min (0.04 ft 3/min) until used. A typical apparatus used to
clean the PEG is shown in Figure 305-3.
7.1.2 Water. Organic-free deionized water is required.
7.1.3 Nitrogen. High-purity nitrogen (less than 0.5 ppm total
hydrocarbons) is used to remove test compounds from the purge
matrix. The source of nitrogen shall be regulated continuously to
40 psig before the on/off toggle valve.
7.2 Volatile Organic Recovery System.
7.2.1 Water. Organic-free deionized water is required.
7.2.2 Desorption Solvent (when used). Appropriate high-purity
(99.99 percent) solvent for desorption shall be used. Analysis
shall be performed (utilizing the same analytical technique as that
used in the analysis of the waste samples) on each lot to determine
purity.
7.3 Analytical System. The gases required for GC operation shall
be of the highest obtainable purity (hydrocarbon free). Consult the
operating manual for recommended settings.
8.0 Sample Collection, Preservation, Storage, and Transport
8.1 Assemble the glassware and associated fittings (see Figures
305-3 and 305-4, as appropriate) and leak-check the system
(approximately 7 psig is the target pressure). After an initial
leak check, mark the pressure gauge and use the initial checkpoint
to monitor for leaks throughout subsequent analyses. If the
pressure in the system drops below the target pressure at any time
during analysis, that analysis shall be considered invalid.
8.2 Recovery Efficiency Determination. Determine the individual
recovery efficiency (RE) for each of the target compounds in
duplicate before the waste samples are analyzed. To determine the
RE, generate a water blank (Section 11.1) and use the injection
port to introduce a known volume of spike solution (or certified
gaseous standard) containing all of the target compounds at the
levels expected in the waste sample. Introduce the spike solution
immediately after the nitrogen purge has been started (Section
8.3.2). Follow the procedures outlined in Section 8.3.3. Analyze
the recovery efficiency samples using the techniques described in
Section 11.2. Determine the recovery efficiency (Equation 305-1,
Section 12.2) by comparing the amount of compound recovered to the
theoretical amount spiked. Determine the RE twice for each
compound; the relative standard deviation, (RSD) shall be ≤10
percent for each compound. If the RSD for any compound is not ≤10
percent, modify the sampling/analytical procedure and complete an
RE study in duplicate, or continue determining RE until the RSD
meets the acceptable criteria. The average RE shall be 0.70 ≤RE
≤1.30 for each compound. If the average RE does not meet these
criteria, an alternative sample collection and/or analysis
technique shall be developed and the recovery efficiency
determination shall be repeated for that compound until the
criteria are met for every target compound. Example modifications
of the sampling/analytical system include changing the adsorbent
material, changing the desorption solvent, utilizing direct thermal
desorption of test compounds from the sorbent tubes, utilizing
another analytical technique.
8.3 Sample Collection and Recovery.
8.3.1 The sample collection procedure in Method 25D shall be
used to collect (into a preweighed vial) 10 g of waste into PEG,
cool, and ship to the laboratory. Remove the sample container from
the cooler and wipe the exterior to remove any ice or water. Weigh
the container and sample to the nearest 0.01 g and record the
weight. Pour the sample from the container into the purge flask.
Rinse the sample container three times with approximately 6 mL of
PEG (or the volume needed to total 50 mL of PEG in the purge
flask), transferring the rinses to the purge flask. Add 50 mL of
organic-free deionized water to the purge flask. Cap the purge
flask tightly in between each rinse and after adding all the
components into the flask.
8.3.2 Allow the oven to equilibrate to 75 ±2 °C (167 ±3.6 °F).
Begin the sample recovery process by turning the toggle valve on,
thus allowing a 6 L/min flow of pure nitrogen through the purge
chamber.
8.3.3 Stop the purge after 30 min. Immediately remove the
sorbent tube(s) from the apparatus and cap both ends. Remove the
knockout trap and transfer the water catch to a 10 mL volumetric
flask. Rinse the trap with organic-free deionized water and
transfer the rinse to the volumetric flask. Dilute to the 10 mL
mark with water. Transfer the water sample to a sample vial and
store at 4 °C (39.2 °F) with zero headspace. The analysis of the
contents of the water knockout trap is optional for this method. If
the target compounds are water soluble, analysis of the water is
recommended; meeting the recovery efficiency criteria in these
cases would be difficult without adding the amount captured in the
knockout trap.
9.0 Quality Control
9.1 Miscellaneous Quality Control Measures.
Section |
Quality control measure |
Effect |
8.1 |
Sampling equipment
leak-check |
Ensures accurate measurement
of sample volume. |
8.2 |
Recovery efficiency (RE)
determination for each measured compound. |
Ensures accurate sample
collection and analysis. |
8.3 |
Calibration of analytical
instrument with at least 3 calibration standards. |
Ensures linear measurement of
compounds over the instrument span. |
10.0 Calibration and Standardization
10.1 The analytical instrument shall be calibrated with a
minimum of three levels of standards for each compound whose
concentrations bracket the concentration of test compounds from the
sorbent tubes. Liquid calibration standards shall be used for
calibration in the analysis of the solvent extracts. The liquid
calibration standards shall be prepared in the desorption solvent
matrix. The calibration standards may be prepared and injected
individually or as a mixture. If thermal desorption and focusing
(onto another sorbent or cryogen focusing) are used, a certified
gaseous mixture or a series of gaseous standards shall be used for
calibration of the instrument. The gaseous standards shall be
focused and analyzed in the same manner as the samples.
10.2 The analytical system shall be certified free from
contaminants before a calibration is performed (see Section 11.1).
The calibration standards are used to determine the linearity of
the analytical system. Perform an initial calibration and linearity
check by analyzing the three calibration standards for each target
compound in triplicate starting with the lowest level and
continuing to the highest level. If the triplicate analyses do not
agree within 5 percent of their average, additional analyses will
be needed until the 5 percent criteria is met. Calculate the
response factor (Equation 305-3, Section 12.4) from the average
area counts of the injections for each concentration level. Average
the response factors of the standards for each compound. The
linearity of the detector is acceptable if the response factor of
each compound at a particular concentration is within 10 percent of
the overall mean response factor for that compound. Analyze daily a
mid-level calibration standard in duplicate and calculate a new
response factor. Compare the daily response factor average to the
average response factor calculated for the mid-level calibration
during the initial linearity check; repeat the three-level
calibration procedure if the daily average response factor differs
from the initial linearity check mid-level response factor by more
than 10 percent. Otherwise, proceed with the sample analysis.
11.0 Analytical Procedure
11.1 Water Blank Analysis. A water blank shall be analyzed daily
to determine the cleanliness of the purge and recovery system. A
water blank is generated by adding 60 mL of organic-free deionized
water to 50 mL of PEG in the purge chamber. Treat the blank as
described in Sections 8.3.2 and 8.3.3. The purpose of the water
blank is to insure that no contaminants exist in the sampling and
analytical apparatus which would interfere with the quantitation of
the target compounds. If contaminants are present, locate the
source of contamination, remove it, and repeat the water blank
analysis.
11.2 Sample Analysis. Sample analysis in the context of this
method refers to techniques to remove the target compounds from the
sorbent tubes, separate them using a chromatography technique, and
quantify them with an appropriate detector. Two types of sample
extraction techniques typically used for sorbents include solvent
desorption or direct thermal desorption of test compounds to a
secondary focusing unit (either sorbent or cryogen based). The test
compounds are then typically transferred to a GC system for
analysis. Other analytical systems may be used (e.g., HPLC) in lieu
of GC systems as long as the recovery efficiency criteria of this
method are met.
11.2.1 Recover the test compounds from the sorbent tubes that
require solvent desorption by transferring the adsorbent material
to a sample vial containing the desorption solvent. The desorption
solvent shall be the same as the solvent used to prepare
calibration standards. The volume of solvent depends on the amount
of adsorbed material to be desorbed (1.0 mL per 100 mg of adsorbent
material) and also on the amount of test compounds present. Final
volume adjustment and or dilution can be made so that the
concentration of test compounds in the desorption solvent is
bracketed by the concentration of the calibration solutions.
Ultrasonicate the desorption solvent for 15 min in an ice bath.
Allow the sample to sit for a period of time so that the adsorbent
material can settle to the bottom of the vial. Transfer the solvent
with a pasteur pipet (minimizing the amount of adsorbent material
taken) to another vial and store at 4 °C (39.2 °F).
11.2.2 Analyze the desorption solvent or direct thermal
desorption tubes from each sample using the same analytical
parameters used for the calibration standard. Calculate the total
weight detected for each compound (Equation 305-4, Section 12.5).
The slope (area/amount) and y-intercept are calculated from the
line bracketed between the two closest calibration points. Correct
the concentration of each waste sample with the appropriate
recovery efficiency factor and the split flow ratio (if used). The
final concentration of each individual test compound is calculated
by dividing the corrected measured weight for that compound by the
weight of the original sample determined in Section 8.3.1 (Equation
305-5, Section 12.6).
11.2.3 Repeat the analysis for the three samples collected in
Section 8.3. Report the corrected concentration of each of the
waste samples, average waste concentration, and relative standard
deviation (Equation 305-6, Section 12.7).
12.0 Data Analysis and Calculations.
12.1 Nomenclature.
AS = Mean area counts of test compound in standard. AU = Mean area
counts of test compound in sample desorption solvent. b =
Y-intercept of the line formed between the two closest calibration
standards that bracket the concentration of the sample. CT = Amount
of test compound (µg) in calibration standard. CF = Correction for
adjusting final amount of sample detected for losses during
individual sample runs. FP = Nitrogen flow through the purge
chamber (6 L/min). FS = Nitrogen split flow directed to the sample
recovery system (use 6 L/min if split flow design was not used).
PPM = Final concentration of test compound in waste sample [µg/g
(which is equivalent to parts per million by weight (ppmw))]. RE =
Recovery efficiency for adjusting final amount of sample detected
for losses due to inefficient trapping and desorption techniques.
R.F. = Response factor for test compound, calculated from a
calibration standard. S = Slope of the line (area counts/CT) formed
between two closest calibration points that bracket the
concentration of the sample. WC = Weight of test compound expected
to be recovered in spike solution based on theoretical amount (µg).
WE = Weight of vial and PEG (g). WF = Weight of vial, PEG and waste
sample (g). WS = Weight of original waste sample (g). WT =
Corrected weight of test compound measured (µg) in sample. WX =
Weight of test compound measured during analysis of recovery
efficiency spike samples (µg).
12.2 Recovery efficiency for determining trapping/desorption
efficiency of individual test compounds in the spike solution,
decimal value.
12.3 Weight of waste sample (g).
12.4 Response factor for individual test compounds.
12.5 Corrected weight of a test compound in the sample, in
µg.
12.6 Final concentration of a test compound in the sample in
ppmw.
12.7 Relative standard deviation (RSD) calculation.
![]()
13.0 Method Performance [Reserved] 14.0
Pollution Prevention [Reserved] 15.0 Waste Management [Reserved]
16.0 References [Reserved] 17.0 Tables, Diagrams, Flowcharts, and
Validation Data

Method 306 -
Determination of Chromium Emissions From Decorative and Hard
Chromium Electroplating and Chromium Anodizing Operations -
Isokinetic Method Note:
This method does not include all of the specifications
(e.g., equipment and supplies) and procedures (e.g.,
sampling and analytical) essential to its performance. Some
material is incorporated by reference from other methods in 40 CFR
Part 60, Appendix A. Therefore, to obtain reliable results, persons
using this method should have a thorough knowledge of at least
Method 5.
1.0 Scope and Application
1.1 Analytes.
Analyte |
CAS No. |
Sensitivity |
Chromium |
7440-47-3 |
See Sec. 13.2. |
1.2 Applicability. This method applies to the determination of
chromium (Cr) in emissions from decorative and hard chrome
electroplating facilities, chromium anodizing operations, and
continuous chromium plating operations at iron and steel
facilities.
1.3 Data Quality Objectives. [Reserved]
2.0 Summary of Method
2.1 Sampling. An emission sample is extracted isokinetically
from the source using an unheated Method 5 sampling train (40 CFR
Part 60, Appendix A), with a glass nozzle and probe liner, but with
the filter omitted. The sample time shall be at least two hours.
The Cr emissions are collected in an alkaline solution containing
0.1 N sodium hydroxide (NaOH) or 0.1 N sodium bicarbonate (NaHCO3).
The collected samples are recovered using an alkaline solution and
are then transported to the laboratory for analysis.
2.2 Analysis.
2.2.1 Total chromium samples with high chromium concentrations
(≥35 µg/L) may be analyzed using inductively coupled plasma
emission spectrometry (ICP) at 267.72 nm.
Note:
The ICP analysis is applicable for this method only when the
solution analyzed has a Cr concentration greater than or equal to
35 µg/L or five times the method detection limit as determined
according to appendix B in 40 CFR part 136. Similarly, inductively
coupled plasma-mass spectroscopy (ICP-MS) may be used for total
chromium analysis provided the procedures for ICP-MS analysis
described in Method 6020 or 6020A (EPA Office of Solid Waste,
publication SW-846) are followed.
2.2.2 Alternatively, when lower total chromium concentrations
(<35 µg/L) are encountered, a portion of the alkaline sample
solution may be digested with nitric acid and analyzed by graphite
furnace atomic absorption spectroscopy (GFAAS) at 357.9 nm.
2.2.3 If it is desirable to determine hexavalent chromium (Cr+6)
emissions, the samples may be analyzed using an ion chromatograph
equipped with a post-column reactor (IC/PCR) and a visible
wavelength detector. To increase sensitivity for trace levels of
Cr+6, a preconcentration system may be used in conjunction with the
IC/PCR.
3.0 Definitions
3.1 Total Chromium - measured chromium content that
includes both major chromium oxidation states (Cr+3, Cr+3).
3.2 May - Implies an optional operation.
3.3 Digestion - The analytical operation involving the
complete (or nearly complete) dissolution of the sample in order to
ensure the complete solubilization of the element (analyte) to be
measured.
3.4 Interferences - Physical, chemical, or spectral
phenomena that may produce a high or low bias in the analytical
result.
3.5 Analytical System - All components of the analytical
process including the sample digestion and measurement
apparatus.
3.6 Sample Recovery - The quantitative transfer of sample
from the collection apparatus to the sample preparation (digestion,
etc.) apparatus. This term should not be confused with analytical
recovery.
3.7 Matrix Modifier - A chemical modification to the
sample during GFAAS determinations to ensure that the analyte is
not lost during the measurement process (prior to the atomization
stage)
3.8 Calibration Reference Standards - Quality control
standards used to check the accuracy of the instrument calibration
curve prior to sample analysis.
3.9 Continuing Check Standard - Quality control standards
used to verify that unacceptable drift in the measurement system
has not occurred.
3.10 Calibration Blank - A blank used to verify that
there has been no unacceptable shift in the baseline either
immediately following calibration or during the course of the
analytical measurement.
3.11 Interference Check - An analytical/measurement
operation that ascertains whether a measurable interference in the
sample exists.
3.12 Interelement Correction Factors - Factors used to
correct for interfering elements that produce a false signal (high
bias).
3.13 Duplicate Sample Analysis - Either the repeat
measurement of a single solution or the measurement of duplicate
preparations of the same sample. It is important to be aware of
which approach is required for a particular type of measurement.
For example, no digestion is required for the ICP determination and
the duplicate instrument measurement is therefore adequate whereas
duplicate digestion/instrument measurements are required for
GFAAS.
3.14 Matrix Spiking - Analytical spikes that have been
added to the actual sample matrix either before (Section 9.2.5.2)
or after (Section 9.1.6). Spikes added to the sample prior
to a preparation technique (e.g., digestion) allow for the
assessment of an overall method accuracy while those added
after only provide for the measurement accuracy
determination.
4.0 Interferences
4.1 ICP Interferences.
4.1.1 ICP Spectral Interferences. Spectral interferences are
caused by: overlap of a spectral line from another element;
unresolved overlap of molecular band spectra; background
contribution from continuous or recombination phenomena; and, stray
light from the line emission of high-concentrated elements.
Spectral overlap may be compensated for by correcting the raw data
with a computer and measuring the interfering element. At the
267.72 nm Cr analytical wavelength, iron, manganese, and uranium
are potential interfering elements. Background and stray light
interferences can usually be compensated for by a background
correction adjacent to the analytical line. Unresolved overlap
requires the selection of an alternative chromium wavelength.
Consult the instrument manufacturer's operation manual for
interference correction procedures.
4.1.2 ICP Physical Interferences. High levels of dissolved
solids in the samples may cause significant inaccuracies due to
salt buildup at the nebulizer and torch tips. This problem can be
controlled by diluting the sample or by extending the rinse times
between sample analyses. Standards shall be prepared in the same
solution matrix as the samples (i.e., 0.1 N NaOH or 0.1 N
NaHCO3).
4.1.3 ICP Chemical Interferences. These include molecular
compound formation, ionization effects and solute vaporization
effects, and are usually not significant in the ICP procedure,
especially if the standards and samples are matrix matched.
4.2 GFAAS Interferences.
4.2.1 GFAAS Chemical Interferences. Low concentrations of
calcium and/or phosphate may cause interferences; at concentrations
above 200 µg/L, calcium's effect is constant and eliminates the
effect of phosphate. Calcium nitrate is therefore added to the
concentrated analyte to ensure a known constant effect. Other
matrix modifiers recommended by the instrument manufacturer may
also be considered.
4.2.2 GFAAS Cyanide Band Interferences. Nitrogen should not be
used as the purge gas due to cyanide band interference.
4.2.3 GFAAS Spectral Interferences. Background correction may be
required because of possible significant levels of nonspecific
absorption and scattering at the 357.9 nm analytical
wavelength.
4.2.4 GFAAS Background Interferences. Zeeman or Smith-Hieftje
background correction is recommended for interferences resulting
from high levels of dissolved solids in the alkaline impinger
solutions.
4.3 IC/PCR Interferences.
4.3.1 IC/PCR Chemical Interferences. Components in the sample
matrix may cause Cr+6 to convert to trivalent chromium (Cr+3) or
cause Cr+3 to convert to Cr+6. The chromatographic separation of
Cr+6 using ion chromatography reduces the potential for other
metals to interfere with the post column reaction. For the IC/PCR
analysis, only compounds that coelute with Cr+6 and affect the
diphenylcarbazide reaction will cause interference.
4.3.2 IC/PCR Background Interferences. Periodic analyses of
reagent water blanks are used to demonstrate that the analytical
system is essentially free of contamination. Sample
cross-contamination can occur when high-level and low-level samples
or standards are analyzed alternately and can be eliminated by
thorough purging of the sample loop. Purging of the sample can
easily be achieved by increasing the injection volume to ten times
the size of the sample loop.
5.0 Safety
5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of
the safety problems associated with its use. It is the
responsibility of the user to establish appropriate safety and
health practices and to determine the applicability of regulatory
limitations prior to performing this test method.
5.2 Hexavalent chromium compounds have been listed as
carcinogens although chromium (III) compounds show little or no
toxicity. Chromium can be a skin and respiratory irritant.
6.0 Equipment and Supplies
6.1 Sampling Train.
6.1.1 A schematic of the sampling train used in this method is
shown in Figure 306-1. The train is the same as shown in Method 5,
Section 6.0 (40 CFR Part 60, Appendix A) except that the probe
liner is unheated, the particulate filter is omitted, and quartz or
borosilicate glass must be used for the probe nozzle and liner in
place of stainless steel.
6.1.2 Probe fittings of plastic such as Teflon, polypropylene,
etc. are recommended over metal fittings to prevent contamination.
If desired, a single combined probe nozzle and liner may be used,
but such a single glass assembly is not a requirement of this
methodology.
6.1.3 Use 0.1 N NaOH or 0.1 N NaHCO3 in the impingers in place
of water.
6.1.4 Operating and maintenance procedures for the sampling
train are described in APTD-0576 of Method 5. Users should read the
APTD-0576 document and adopt the outlined procedures. Alternative
mercury-free thermometers may be used if the thermometers are, at a
minimum, equivalent in terms of performance or suitably effective
for the specific temperature measurement application.
6.1.5 Similar collection systems which have been approved by the
Administrator may be used.
6.2 Sample Recovery. Same as Method 5, [40 CFR Part 60, Appendix
A], with the following exceptions:
6.2.1 Probe-Liner and Probe-Nozzle Brushes. Brushes are not
necessary for sample recovery. If a probe brush is used, it must be
non-metallic.
6.2.2 Sample Recovery Solution. Use 0.1 N NaOH or 0.1 N NaHCO3,
whichever is used as the impinger absorbing solution, in place of
acetone to recover the sample.
6.2.3 Sample Storage Containers. Polyethylene, with leak-free
screw cap, 250 mL, 500 mL or 1,000 mL.
6.3 Analysis.
6.3.1 General. For analysis, the following equipment is
needed.
6.3.1.1 Phillips Beakers. (Phillips beakers are preferred, but
regular beakers may also be used.)
6.3.1.2 Hot Plate.
6.3.1.3 Volumetric Flasks. Class A, various sizes as
appropriate.
6.3.1.4 Assorted Pipettes.
6.3.2 Analysis by ICP.
6.3.2.1 ICP Spectrometer. Computer-controlled emission
spectrometer with background correction and radio frequency
generator.
6.3.2.2 Argon Gas Supply. Welding grade or better.
6.3.3 Analysis by GFAAS.
6.3.3.1 Chromium Hollow Cathode Lamp or Electrodeless Discharge
Lamp.
6.3.3.2 Graphite Furnace Atomic Absorption
Spectrophotometer.
6.3.3.3 Furnace Autosampler.
6.3.4 Analysis by IC/PCR.
6.3.4.1 IC/PCR System. High performance liquid chromatograph
pump, sample injection valve, post-column reagent delivery and
mixing system, and a visible detector, capable of operating at 520
nm-540 nm, all with a non-metallic (or inert) flow path. An
electronic peak area mode is recommended, but other recording
devices and integration techniques are acceptable provided the
repeatability criteria and the linearity criteria for the
calibration curve described in Section 10.4 can be satisfied. A
sample loading system is required if preconcentration is
employed.
6.3.4.2 Analytical Column. A high performance ion chromatograph
(HPIC) non-metallic column with anion separation characteristics
and a high loading capacity designed for separation of metal
chelating compounds to prevent metal interference. Resolution
described in Section 11.6 must be obtained. A non-metallic guard
column with the same ion-exchange material is recommended.
6.3.4.3 Preconcentration Column (for older instruments). An HPIC
non-metallic column with acceptable anion retention characteristics
and sample loading rates must be used as described in Section
11.6.
6.3.4.4 Filtration Apparatus for IC/PCR.
6.3.4.4.1 Teflon, or equivalent, filter holder to accommodate
0.45-µm acetate, or equivalent, filter, if needed to remove
insoluble particulate matter.
6.3.4.4.2 0.45-µm Filter Cartridge. For the removal of insoluble
material. To be used just prior to sample injection/analysis.
7.0 Reagents and Standards Note:
Unless otherwise indicated, all reagents should conform to the
specifications established by the Committee on Analytical Reagents
of the American Chemical Society (ACS reagent grade). Where such
specifications are not available, use the best available grade.
Reagents should be checked by the appropriate analysis prior to
field use to assure that contamination is below the analytical
detection limit for the ICP or GFAAS total chromium analysis; and
that contamination is below the analytical detection limit for Cr+6
using IC/PCR for direct injection or, if selected,
preconcentration.
7.1 Sampling.
7.1.1 Water. Reagent water that conforms to ASTM Specification
D1193-77 or 91 Type II (incorporated by reference see § 63.14). All
references to water in the method refer to reagent water unless
otherwise specified. It is recommended that water blanks be checked
prior to preparing the sampling reagents to ensure that the Cr
content is less than three (3) times the anticipated detection
limit of the analytical method.
7.1.2 Sodium Hydroxide (NaOH) Absorbing Solution, 0.1 N.
Dissolve 4.0 g of sodium hydroxide in 1 liter of water to obtain a
pH of approximately 8.5.
7.1.3 Sodium Bicarbonate (NaHCO3) Absorbing Solution, 0.1 N.
Dissolve approximately 8.5 g of sodium bicarbonate in 1 liter of
water to obtain a pH of approximately 8.3.
7.1.4 Chromium Contamination.
7.1.4.1 The absorbing solution shall not exceed the QC criteria
noted in Section 7.1.1 (≤3 times the instrument detection
limit).
7.1.4.2 When the Cr+6 content in the field samples exceeds the
blank concentration by at least a factor of ten (10), Cr+6 blank
concentrations ≥10 times the detection limit will be allowed.
Note:
At sources with high concentrations of acids and/or SO2, the
concentration of NaOH or NaHCO3 should be ≥0.5 N to insure that the
pH of the solution remains at or above 8.5 for NaOH and 8.0 for
NaHCO3 during and after sampling.
7.1.5 Silica Gel. Same as in Method 5.
7.2 Sample Recovery.
7.2.1 0.1 N NaOH or 0.1 N NaHCO3. Use the same solution for the
sample recovery that is used for the impinger absorbing
solution.
7.2.2 pH Indicator Strip, for IC/PCR. pH indicator capable of
determining the pH of solutions between the pH range of 7 and 12,
at 0.5 pH increments.
7.3 Sample Preparation and Analysis.
7.3.1 Nitric Acid (HNO3), Concentrated, for GFAAS. Trace metals
grade or better HNO3 must be used for reagent preparation. The ACS
reagent grade HNO3 is acceptable for cleaning glassware.
7.3.2 HNO3, 1.0% (v/v), for GFAAS. Prepare, by slowly stirring,
10 mL of concentrated HNO3) into 800 mL of reagent water. Dilute to
1,000 mL with reagent water. The solution shall contain less than
0.001 mg Cr/L.
7.3.3 Calcium Nitrate Ca(NO3)2 Solution (10 µg Ca/mL) for GFAAS
analysis. Prepare the solution by weighing 40.9 mg of Ca(NO3)2 into
a 1 liter volumetric flask. Dilute with reagent water to 1
liter.
7.3.4 Matrix Modifier, for GFAAS. See instrument manufacturer's
manual for suggested matrix modifier.
7.3.5 Chromatographic Eluent, for IC/PCR. The eluent used in the
analytical system is ammonium sulfate based.
7.3.5.1 Prepare by adding 6.5 mL of 29 percent ammonium
hydroxide (NH4OH) and 33 g of ammonium sulfate ((NH4)2SO4) to 500
mL of reagent water. Dilute to 1 liter with reagent water and mix
well.
7.3.5.2 Other combinations of eluents and/or columns may be
employed provided peak resolution, repeatability, linearity, and
analytical sensitivity as described in Sections 9.3 and 11.6 are
acceptable.
7.3.6 Post-Column Reagent, for IC/PCR. An effective post-column
reagent for use with the chromatographic eluent described in
Section 7.3.5 is a diphenylcarbazide (DPC)-based system. Dissolve
0.5 g of 1,5-diphenylcarbazide in 100 mL of ACS grade methanol. Add
500 mL of reagent water containing 50 mL of 96 percent
spectrophotometric grade sulfuric acid. Dilute to 1 liter with
reagent water.
7.3.7 Chromium Standard Stock Solution (1000 mg/L). Procure a
certified aqueous standard or dissolve 2.829 g of potassium
dichromate (K2Cr2O7), in reagent water and dilute to 1 liter.
7.3.8 Calibration Standards for ICP or IC/PCR. Prepare
calibration standards for ICP or IC/PCR by diluting the Cr standard
stock solution (Section 7.3.7) with 0.1 N NaOH or 0.1 N NaHCO3,
whichever is used as the impinger absorbing solution, to achieve a
matrix similar to the actual field samples. Suggested levels are 0,
50, 100, and 200 µg Cr/L for ICP, and 0, 1, 5, and 10 µg Cr+6/L for
IC/PCR.
7.3.9 Calibration Standards for GFAAS. Chromium solutions for
GFAAS calibration shall contain 1.0 percent (v/v) HNO3. The zero
standard shall be 1.0 percent (v/v) HNO3. Calibration standards
should be prepared daily by diluting the Cr standard stock solution
(Section 7.3.7) with 1.0 percent HNO3. Use at least four standards
to make the calibration curve. Suggested levels are 0, 10, 50, and
100 µg Cr/L.
7.4 Glassware Cleaning Reagents.
7.4.1 HNO3, Concentrated. ACS reagent grade or equivalent.
7.4.2 Water. Reagent water that conforms to ASTM Specification
D1193-77 or 91 Type II.
7.4.3 HNO3, 10 percent (v/v). Add by stirring 500 mL of
concentrated HNO3 into a flask containing approximately 4,000 mL of
reagent water. Dilute to 5,000 mL with reagent water. Mix well. The
reagent shall contain less than 2 µg Cr/L.
8.0 Sample Collection, Preservation, Holding Times, Storage, and
Transport Note:
Prior to sample collection, consideration should be given to the
type of analysis (Cr+6 or total Cr) that will be performed. Which
analysis option(s) will be performed will determine which sample
recovery and storage procedures will be required to process the
sample.
8.1 Sample Collection. Same as Method 5 (40 CFR part 60,
appendix A), with the following exceptions.
8.1.1 Omit the particulate filter and filter holder from the
sampling train. Use a glass nozzle and probe liner instead of
stainless steel. Do not heat the probe. Place 100 mL of 0.1 N NaOH
or 0.1 N NaHCO3 in each of the first two impingers, and record the
data for each run on a data sheet such as shown in Figure
306-2.
8.1.2 Clean all glassware prior to sampling in hot soapy water
designed for laboratory cleaning of glassware. Next, rinse the
glassware three times with tap water, followed by three additional
rinses with reagent water. Then soak the glassware in 10% (v/v)
HNO3 solution for a minimum of 4 hours, rinse three times with
reagent water, and allow to air dry. Cover all glassware openings
where contamination can occur with Parafilm, or equivalent, until
the sampling train is assembled for sampling.
8.1.3 Train Operation. Follow the basic procedures outlined in
Method 5 in conjunction with the following instructions. Train
sampling rate shall not exceed 0.030 m 3/min (1.0 cfm) during a
run.
8.2 Sample Recovery. Follow the basic procedures of Method 5,
with the exceptions noted.
8.2.1 A particulate filter is not recovered from this train.
8.2.2 Tester shall select either the total Cr or Cr+6 sample
recovery option.
8.2.3 Samples to be analyzed for both total Cr and Cr+6, shall
be recovered using the Cr+6 sample option (Section 8.2.6).
8.2.4 A field reagent blank shall be collected for either of the
Cr or the Cr+6 analysis. If both analyses (Cr and Cr+6) are to be
conducted on the samples, collect separate reagent blanks for each
analysis.
Note:
Since particulate matter is not usually present at chromium
electroplating and/or chromium anodizing operations, it is not
necessary to filter the Cr+6 samples unless there is observed
sediment in the collected solutions. If it is necessary to filter
the Cr+6 solutions, please refer to Method 0061, Determination of
Hexavalent Chromium Emissions From Stationary Sources, Section 7.4,
Sample Preparation in SW-846 (see Reference 1).
8.2.5 Total Cr Sample Option.
8.2.5.1 Container No. 1. Measure the volume of the liquid in the
first, second, and third impingers and quantitatively transfer into
a labeled sample container.
8.2.5.2 Use approximately 200 to 300 mL of the 0.1 N NaOH or 0.1
N NaHCO3 absorbing solution to rinse the probe nozzle, probe liner,
three impingers, and connecting glassware; add this rinse to
Container No. 1.
8.2.6 Cr+6 Sample Option.
8.2.6.1 Container No. 1. Measure and record the pH of the
absorbing solution contained in the first impinger at the
end of the sampling run using a pH indicator strip. The pH of the
solution must be ≥8.5 for NaOH and ≥8.0 for NaHCO3. If it is not,
discard the collected sample, increase the normality of the NaOH or
NaHCO3 impinger absorbing solution to 0.5 N or to a solution
normality approved by the Administrator and collect another air
emission sample.
8.2.6.2 After determining the pH of the first impinger solution,
combine and measure the volume of the liquid in the first, second,
and third impingers and quantitatively transfer into the labeled
sample container. Use approximately 200 to 300 mL of the 0.1 N NaOH
or 0.1 N NaHCO3 absorbing solution to rinse the probe nozzle, probe
liner, three impingers, and connecting glassware; add this rinse to
Container No. 1.
8.2.7 Field Reagent Blank.
8.2.7.1 Container No. 2.
8.2.7.2 Place approximately 500 mL of the 0.1 N NaOH or 0.1 N
NaHCO3 absorbing solution into a labeled sample container.
8.3 Sample Preservation, Storage, and Transport.
8.3.1 Total Cr Sample Option. Samples to be analyzed for total
Cr need not be refrigerated.
8.3.2 Cr+6 Sample Option. Samples to be analyzed for Cr+6 must
be shipped and stored at 4 °C. Allow Cr+6 samples to return to
ambient temperature prior to analysis.
8.4 Sample Holding Times.
8.4.1 Total Cr Sample Option. Samples to be analyzed for total
Cr shall be analyzed within 60 days of collection.
8.4.2 Cr+6 Sample Option. Samples to be analyzed for Cr+6 shall
be analyzed within 14 days of collection.
9.0 Quality Control
9.1 ICP Quality Control.
9.1.1 ICP Calibration Reference Standards. Prepare a calibration
reference standard using the same alkaline matrix as the
calibration standards; it should be at least 10 times the
instrumental detection limit.
9.1.1.1 This reference standard must be prepared from a
different Cr stock solution source than that used for preparation
of the calibration curve standards.
9.1.1.2 Prior to sample analysis, analyze at least one reference
standard.
9.1.1.3 The calibration reference standard must be measured
within 10 percent of it's true value for the curve to be considered
valid.
9.1.1.4 The curve must be validated before sample analyses are
performed.
9.1.2 ICP Continuing Check Standard.
9.1.2.1 Perform analysis of the check standard with the field
samples as described in Section 11.2 (at least after every 10
samples, and at the end of the analytical run).
9.1.2.2 The check standard can either be the mid-range
calibration standard or the reference standard. The results of the
check standard shall agree within 10 percent of the expected value;
if not, terminate the analyses, correct the problem, recalibrate
the instrument, and rerun all samples analyzed subsequent to the
last acceptable check standard analysis.
9.1.3 ICP Calibration Blank.
9.1.3.1 Perform analysis of the calibration blank with the field
samples as described in Section 11.2 (at least after every 10
samples, and at the end of the analytical run).
9.1.3.2 The results of the calibration blank shall agree within
three standard deviations of the mean blank value. If not, analyze
the calibration blank two more times and average the results. If
the average is not within three standard deviations of the
background mean, terminate the analyses, correct the problem,
recalibrate, and reanalyze all samples analyzed subsequent to the
last acceptable calibration blank analysis.
9.1.4 ICP Interference Check. Prepare an interference check
solution that contains known concentrations of interfering elements
that will provide an adequate test of the correction factors in the
event of potential spectral interferences.
9.1.4.1 Two potential interferences, iron and manganese, may be
prepared as 1000 µg/mL and 200 µg/mL solutions, respectively. The
solutions should be prepared in dilute HNO3 (1-5 percent).
Particular care must be used to ensure that the solutions and/or
salts used to prepare the solutions are of ICP grade purity
(i.e., that no measurable Cr contamination exists in the
salts/solutions). Commercially prepared interfering element check
standards are available.
9.1.4.2 Verify the interelement correction factors every three
months by analyzing the interference check solution. The correction
factors are calculated according to the instrument manufacturer's
directions. If the interelement correction factors are used
properly, no false Cr should be detected.
9.1.4.3 Negative results with an absolute value greater than
three (3) times the detection limit are usually the results of the
background correction position being set incorrectly. Scan the
spectral region to ensure that the correction position has not been
placed on an interfering peak.
9.1.5 ICP Duplicate Sample Analysis. Perform one duplicate
sample analysis for each compliance sample batch (3 runs).
9.1.5.1 As there is no sample preparation required for the ICP
analysis, a duplicate analysis is defined as a repeat analysis of
one of the field samples. The selected sample shall be analyzed
using the same procedures that were used to analyze the original
sample.
9.1.5.2 Duplicate sample analyses shall agree within 10 percent
of the original measurement value.
9.1.5.3 Report the original analysis value for the sample and
report the duplicate analysis value as the QC check value. If
agreement is not achieved, perform the duplicate analysis again. If
agreement is not achieved the second time, perform corrective
action to identify and correct the problem before analyzing the
sample for a third time.
9.1.6 ICP Matrix Spiking. Spiked samples shall be prepared and
analyzed daily to ensure that there are no matrix effects, that
samples and standards have been matrix-matched, and that the
laboratory equipment is operating properly.
9.1.6.1 Spiked sample recovery analyses should indicate a
recovery for the Cr spike of between 75 and 125 percent.
9.1.6.2 Cr levels in the spiked sample should provide final
solution concentrations that are within the linear portion of the
calibration curve, as well as, at a concentration level at least:
equal to that of the original sample; and, ten (10) times the
detection limit.
9.1.6.3 If the spiked sample concentration meets the stated
criteria but exceeds the linear calibration range, the spiked
sample must be diluted with the field absorbing solution.
9.1.6.4 If the recoveries for the Cr spiked samples do not meet
the specified criteria, perform corrective action to identify and
correct the problem prior to reanalyzing the samples.
9.1.7 ICP Field Reagent Blank.
9.1.7.1 Analyze a minimum of one matrix-matched field reagent
blank (Section 8.2.4) per sample batch to determine if
contamination or memory effects are occurring.
9.1.7.2 If contamination or memory effects are observed, perform
corrective action to identify and correct the problem before
reanalyzing the samples.
9.2 GFAAS Quality Control.
9.2.1 GFAAS Calibration Reference Standards. The calibration
curve must be verified by using at least one calibration reference
standard (made from a reference material or other independent
standard material) at or near the mid-range of the calibration
curve.
9.2.1.1 The calibration curve must be validated before sample
analyses are performed.
9.2.1.2 The calibration reference standard must be measured
within 10 percent of its true value for the curve to be considered
valid.
9.2.2 GFAAS Continuing Check Standard.
9.2.2.1 Perform analysis of the check standard with the field
samples as described in Section 11.4 (at least after every 10
samples, and at the end of the analytical run).
9.2.2.2 These standards are analyzed, in part, to monitor the
life and performance of the graphite tube. Lack of reproducibility
or a significant change in the signal for the check standard may
indicate that the graphite tube should be replaced.
9.2.2.3 The check standard may be either the mid-range
calibration standard or the reference standard.
9.2.2.4 The results of the check standard shall agree within 10
percent of the expected value.
9.2.2.5 If not, terminate the analyses, correct the problem,
recalibrate the instrument, and reanalyze all samples analyzed
subsequent to the last acceptable check standard analysis.
9.2.3 GFAAS Calibration Blank.
9.2.3.1 Perform analysis of the calibration blank with the field
samples as described in Section 11.4 (at least after every 10
samples, and at the end of the analytical run).
9.2.3.2 The calibration blank is analyzed to monitor the life
and performance of the graphite tube as well as the existence of
any memory effects. Lack of reproducibility or a significant change
in the signal, may indicate that the graphite tube should be
replaced.
9.2.3.3 The results of the calibration blank shall agree within
three standard deviations of the mean blank value.
9.2.3.4 If not, analyze the calibration blank two more times and
average the results. If the average is not within three standard
deviations of the background mean, terminate the analyses, correct
the problem, recalibrate, and reanalyze all samples analyzed
subsequent to the last acceptable calibration blank analysis.
9.2.4 GFAAS Duplicate Sample Analysis. Perform one duplicate
sample analysis for each compliance sample batch (3 runs).
9.2.4.1 A digested aliquot of the selected sample is processed
and analyzed using the identical procedures that were used for the
whole sample preparation and analytical efforts.
9.2.4.2 Duplicate sample analyses results incorporating
duplicate digestions shall agree within 20 percent for sample
results exceeding ten (10) times the detection limit.
9.2.4.3 Report the original analysis value for the sample and
report the duplicate analysis value as the QC check value.
9.2.4.4 If agreement is not achieved, perform the duplicate
analysis again. If agreement is not achieved the second time,
perform corrective action to identify and correct the problem
before analyzing the sample for a third time.
9.2.5 GFAAS Matrix Spiking.
9.2.5.1 Spiked samples shall be prepared and analyzed daily to
ensure that (1) correct procedures are being followed, (2) there
are no matrix effects and (3) all equipment is operating
properly.
9.2.5.2 Cr spikes are added prior to any sample preparation.
9.2.5.3 Cr levels in the spiked sample should provide final
solution concentrations that are within the linear portion of the
calibration curve, as well as, at a concentration level at least:
equal to that of the original sample; and, ten (10) times the
detection limit.
9.2.5.4 Spiked sample recovery analyses should indicate a
recovery for the Cr spike of between 75 and 125 percent.
9.2.5.5 If the recoveries for the Cr spiked samples do not meet
the specified criteria, perform corrective action to identify and
correct the problem prior to reanalyzing the samples.
9.2.6 GFAAS Method of Standard Additions.
9.2.6.1 Method of Standard Additions. Perform procedures in
Section 5.4 of Method 12 (40 CFR Part 60, Appendix A)
9.2.6.2 Whenever sample matrix problems are suspected and
standard/sample matrix matching is not possible or whenever a new
sample matrix is being analyzed, perform referenced procedures to
determine if the method of standard additions is necessary.
9.2.7 GFAAS Field Reagent Blank.
9.2.7.1 Analyze a minimum of one matrix-matched field reagent
blank (Section 8.2.4) per sample batch to determine if
contamination or memory effects are occurring.
9.2.7.2 If contamination or memory effects are observed, perform
corrective action to identify and correct the problem before
reanalyzing the samples.
9.3 IC/PCR Quality Control.
9.3.1 IC/PCR Calibration Reference Standards.
9.3.1.1 Prepare a calibration reference standard at a
concentration that is at or near the mid-point of the calibration
curve using the same alkaline matrix as the calibration standards.
This reference standard should be prepared from a different Cr
stock solution than that used to prepare the calibration curve
standards. The reference standard is used to verify the accuracy of
the calibration curve.
9.3.1.2 The curve must be validated before sample analyses are
performed. Prior to sample analysis, analyze at least one reference
standard with an expected value within the calibration range.
9.3.1.3 The results of this reference standard analysis must be
within 10 percent of the true value of the reference standard for
the calibration curve to be considered valid.
9.3.2 IC/PCR Continuing Check Standard and Calibration
Blank.
9.3.2.1 Perform analysis of the check standard and the
calibration blank with the field samples as described in Section
11.6 (at least after every 10 samples, and at the end of the
analytical run).
9.3.2.2 The result from the check standard must be within 10
percent of the expected value.
9.3.2.3 If the 10 percent criteria is exceeded, excessive drift
and/or instrument degradation may have occurred, and must be
corrected before further analyses can be performed.
9.3.2.4 The results of the calibration blank analyses must agree
within three standard deviations of the mean blank value.
9.3.2.5 If not, analyze the calibration blank two more times and
average the results.
9.3.2.6 If the average is not within three standard deviations
of the background mean, terminate the analyses, correct the
problem, recalibrate, and reanalyze all samples analyzed subsequent
to the last acceptable calibration blank analysis.
9.3.3 IC/PCR Duplicate Sample Analysis.
9.3.3.1 Perform one duplicate sample analysis for each
compliance sample batch (3 runs).
9.3.3.2 An aliquot of the selected sample is prepared and
analyzed using procedures identical to those used for the emission
samples (for example, filtration and/or, if necessary,
preconcentration).
9.3.3.3 Duplicate sample injection results shall agree within 10
percent for sample results exceeding ten (10) times the detection
limit.
9.3.3.4 Report the original analysis value for the sample and
report the duplicate analysis value as the QC check value.
9.3.3.5 If agreement is not achieved, perform the duplicate
analysis again.
9.3.3.6 If agreement is not achieved the second time, perform
corrective action to identify and correct the problem prior to
analyzing the sample for a third time.
9.3.4 ICP/PCR Matrix Spiking. Spiked samples shall be prepared
and analyzed with each sample set to ensure that there are no
matrix effects, that samples and standards have been
matrix-matched, and that the equipment is operating properly.
9.3.4.1 Spiked sample recovery analysis should indicate a
recovery of the Cr+6 spike between 75 and 125 percent.
9.3.4.2 The spiked sample concentration should be within the
linear portion of the calibration curve and should be equal to or
greater than the concentration of the original sample. In addition,
the spiked sample concentration should be at least ten (10) times
the detection limit.
9.3.4.3 If the recoveries for the Cr+6 spiked samples do not
meet the specified criteria, perform corrective action to identify
and correct the problem prior to reanalyzing the samples.
9.3.5 IC/PCR Field Reagent Blank.
9.3.5.1 Analyze a minimum of one matrix-matched field reagent
blank (Section 8.2.4) per sample batch to determine if
contamination or memory effects are occurring.
9.3.5.2 If contamination or memory effects are observed, perform
corrective action to identify and correct the problem before
reanalyzing the samples.
10.0 Calibration and Standardization
10.1 Sampling Train Calibration. Perform calibrations described
in Method 5, (40 CFR part 60, appendix A). The alternate
calibration procedures described in Method 5, may also be used.
10.2 ICP Calibration.
10.2.1 Calibrate the instrument according to the instrument
manufacturer's recommended procedures, using a calibration blank
and three standards for the initial calibration.
10.2.2 Calibration standards should be prepared fresh daily, as
described in Section 7.3.8. Be sure that samples and calibration
standards are matrix matched. Flush the system with the calibration
blank between each standard.
10.2.3 Use the average intensity of multiple exposures (3 or
more) for both standardization and sample analysis to reduce random
error.
10.2.4 Employing linear regression, calculate the correlation
coefficient .
10.2.5 The correlation coefficient must equal or exceed
0.995.
10.2.6 If linearity is not acceptable, prepare and rerun another
set of calibration standards or reduce the range of the calibration
standards, as necessary.
10.3 GFAAS Calibration.
10.3.1 For instruments that measure directly in concentration,
set the instrument software to display the correct concentration,
if applicable.
10.3.2 Curve must be linear in order to correctly perform the
method of standard additions which is customarily performed
automatically with most instrument computer-based data systems.
10.3.3 The calibration curve (direct calibration or standard
additions) must be prepared daily with a minimum of a calibration
blank and three standards that are prepared fresh daily.
10.3.4 The calibration curve acceptance criteria must equal or
exceed 0.995.
10.3.5 If linearity is not acceptable, prepare and rerun another
set of calibration standards or reduce the range of calibration
standards, as necessary.
10.4 IC/PCR Calibration.
10.4.1 Prepare a calibration curve using the calibration blank
and three calibration standards prepared fresh daily as described
in Section 7.3.8.
10.4.2 The calibration curve acceptance criteria must equal or
exceed 0.995.
10.4.3 If linearity is not acceptable, remake and/or rerun the
calibration standards. If the calibration curve is still
unacceptable, reduce the range of the curve.
10.4.4 Analyze the standards with the field samples as described
in Section 11.6.
11.0 Analytical Procedures Note:
The method determines the chromium concentration in µg Cr/mL. It
is important that the analyst measure the field sample volume prior
to analyzing the sample. This will allow for conversion of µg Cr/mL
to µg Cr/sample.
11.1 ICP Sample Preparation.
11.1.1 The ICP analysis is performed directly on the alkaline
impinger solution; acid digestion is not necessary, provided the
samples and standards are matrix matched.
11.1.2 The ICP analysis should only be employed when the
solution analyzed has a Cr concentration greater than 35 µg/L or
five times the method detection limit as determined according to
Appendix B in 40 CFR Part 136 or by other commonly accepted
analytical procedures.
11.2 ICP Sample Analysis.
11.2.1 The ICP analysis is applicable for the determination of
total chromium only.
11.2.2 ICP Blanks. Two types of blanks are required for the ICP
analysis.
11.2.2.1 Calibration Blank. The calibration blank is used in
establishing the calibration curve. For the calibration blank, use
either 0.1 N NaOH or 0.1 N NaHCO3, whichever is used for the
impinger absorbing solution. The calibration blank can be prepared
fresh in the laboratory; it does not have to be prepared from the
same batch of solution that was used in the field. A sufficient
quantity should be prepared to flush the system between standards
and samples.
11.2.2.2 Field Reagent Blank. The field reagent blank is
collected in the field during the testing program. The field
reagent blank (Section 8.2.4) is an aliquot of the absorbing
solution prepared in Section 7.1.2. The reagent blank is used to
assess possible contamination resulting from sample processing.
11.2.3 ICP Instrument Adjustment.
11.2.3.1 Adjust the ICP instrument for proper operating
parameters including wavelength, background correction settings (if
necessary), and interfering element correction settings (if
necessary).
11.2.3.2 The instrument must be allowed to become thermally
stable before beginning measurements (usually requiring at least 30
min of operation prior to calibration). During this warmup period,
the optical calibration and torch position optimization may be
performed (consult the operator's manual).
11.2.4 ICP Instrument Calibration.
11.2.4.1 Calibrate the instrument according to the instrument
manufacturer's recommended procedures, and the procedures specified
in Section 10.2.
11.2.4.2 Prior to analyzing the field samples, reanalyze the
highest calibration standard as if it were a sample.
11.2.4.3 Concentration values obtained should not deviate from
the actual values or from the established control limits by more
than 5 percent, whichever is lower (see Sections 9.1 and 10.2).
11.2.4.4 If they do, follow the recommendations of the
instrument manufacturer to correct the problem.
11.2.5 ICP Operational Quality Control Procedures.
11.2.5.1 Flush the system with the calibration blank solution
for at least 1 min before the analysis of each sample or
standard.
11.2.5.2 Analyze the continuing check standard and the
calibration blank after each batch of 10 samples.
11.2.5.3 Use the average intensity of multiple exposures for
both standardization and sample analysis to reduce random
error.
11.2.6 ICP Sample Dilution.
11.2.6.1 Dilute and reanalyze samples that are more concentrated
than the linear calibration limit or use an alternate, less
sensitive Cr wavelength for which quality control data have already
been established.
11.2.6.2 When dilutions are performed, the appropriate factors
must be applied to sample measurement results.
11.2.7 Reporting Analytical Results. All analytical results
should be reported in µg Cr/mL using three significant figures.
Field sample volumes (mL) must be reported also.
11.3 GFAAS Sample Preparation.
11.3.1 GFAAS Acid Digestion. An acid digestion of the alkaline
impinger solution is required for the GFAAS analysis.
11.3.1.1 In a beaker, add 10 mL of concentrated HNO3 to a 100 mL
sample aliquot that has been well mixed. Cover the beaker with a
watch glass. Place the beaker on a hot plate and reflux the sample
to near dryness. Add another 5 mL of concentrated HNO3 to complete
the digestion. Again, carefully reflux the sample volume to near
dryness. Rinse the beaker walls and watch glass with reagent
water.
11.3.1.2 The final concentration of HNO3 in the solution should
be 1 percent (v/v).
11.3.1.3 Transfer the digested sample to a 50-mL volumetric
flask. Add 0.5 mL of concentrated HNO3 and 1 mL of the 10 µg/mL of
Ca(NO3)2. Dilute to 50 mL with reagent water.
11.3.2 HNO3 Concentration. A different final volume may be used
based on the expected Cr concentration, but the HNO3 concentration
must be maintained at 1 percent (v/v).
11.4 GFAAS Sample Analysis.
11.4.1 The GFAAS analysis is applicable for the determination of
total chromium only.
11.4.2 GFAAS Blanks. Two types of blanks are required for the
GFAAS analysis.
11.4.2.1 Calibration Blank. The 1.0 percent HNO3 is the
calibration blank which is used in establishing the calibration
curve.
11.4.2.2 Field Reagent Blank. An aliquot of the 0.1 N NaOH
solution or the 0.1 N NaHCO3 prepared in Section 7.1.2 is collected
for the field reagent blank. The field reagent blank is used to
assess possible contamination resulting from processing the
sample.
11.4.2.2.1 The reagent blank must be subjected to the entire
series of sample preparation and analytical procedures, including
the acid digestion.
11.4.2.2.2 The reagent blank's final solution must contain the
same acid concentration as the sample solutions.
11.4.3 GFAAS Instrument Adjustment.
11.4.3.1 The 357.9 nm wavelength line shall be used.
11.4.3.2 Follow the manufacturer's instructions for all other
spectrophotometer operating parameters.
11.4.4 Furnace Operational Parameters. Parameters suggested by
the manufacturer should be employed as guidelines.
11.4.4.1 Temperature-sensing mechanisms and temperature
controllers can vary between instruments and/or with time; the
validity of the furnace operating parameters must be periodically
confirmed by systematically altering the furnace parameters while
analyzing a standard. In this manner, losses of analyte due to
higher-than-necessary temperature settings or losses in sensitivity
due to less than optimum settings can be minimized.
11.4.4.2 Similar verification of furnace operating parameters
may be required for complex sample matrices (consult instrument
manual for additional information). Calibrate the GFAAS system
following the procedures specified in Section 10.3.
11.4.5 GFAAS Operational Quality Control Procedures.
11.4.5.1 Introduce a measured aliquot of digested sample into
the furnace and atomize.
11.4.5.2 If the measured concentration exceeds the calibration
range, the sample should be diluted with the calibration blank
solution (1.0 percent HNO3) and reanalyzed.
11.4.5.3 Consult the operator's manual for suggested injection
volumes. The use of multiple injections can improve accuracy and
assist in detecting furnace pipetting errors.
11.4.5.4 Analyze a minimum of one matrix-matched reagent blank
per sample batch to determine if contamination or any memory
effects are occurring.
11.4.5.5 Analyze a calibration blank and a continuing check
standard after approximately every batch of 10 sample
injections.
11.4.6 GFAAS Sample Dilution.
11.4.6.1 Dilute and reanalyze samples that are more concentrated
than the instrument calibration range.
11.4.6.2 If dilutions are performed, the appropriate factors
must be applied to sample measurement results.
11.4.7 Reporting Analytical Results.
11.4.7.1 Calculate the Cr concentrations by the method of
standard additions (see operator's manual) or, from direct
calibration. All dilution and/or concentration factors must be used
when calculating the results.
11.4.7.2 Analytical results should be reported in µg Cr/mL using
three significant figures. Field sample volumes (mL) must be
reported also.
11.5 IC/PCR Sample Preparation.
11.5.1 Sample pH. Measure and record the sample pH prior to
analysis.
11.5.2 Sample Filtration. Prior to preconcentration and/or
analysis, filter all field samples through a 0.45-µm filter. The
filtration step should be conducted just prior to sample
injection/analysis.
11.5.2.1 Use a portion of the sample to rinse the syringe
filtration unit and acetate filter and then collect the required
volume of filtrate.
11.5.2.2 Retain the filter if total Cr is to be determined
also.
11.5.3 Sample Preconcentration (older instruments).
11.5.3.1 For older instruments, a preconcentration system may be
used in conjunction with the IC/PCR to increase sensitivity for
trace levels of Cr+6.
11.5.3.2 The preconcentration is accomplished by selectively
retaining the analyte on a solid absorbent, followed by removal of
the analyte from the absorbent (consult instrument manual).
11.5.3.3 For a manual system, position the injection valve so
that the eluent displaces the concentrated Cr+6 sample,
transferring it from the preconcentration column and onto the IC
anion separation column.
11.6 IC/PCR Sample Analyses.
11.6.1 The IC/PCR analysis is applicable for hexavalent chromium
measurements only.
11.6.2 IC/PCR Blanks. Two types of blanks are required for the
IC/PCR analysis.
11.6.2.1 Calibration Blank. The calibration blank is used in
establishing the analytical curve. For the calibration blank, use
either 0.1 N NaOH or 0.1 N NaHCO3, whichever is used for the
impinger solution. The calibration blank can be prepared fresh in
the laboratory; it does not have to be prepared from the same batch
of absorbing solution that is used in the field.
11.6.2.2 Field Reagent Blank. An aliquot of the 0.1 N NaOH
solution or the 0.1 N NaHCO3 solution prepared in Section 7.1.2 is
collected for the field reagent blank. The field reagent blank is
used to assess possible contamination resulting from processing the
sample.
11.6.3 Stabilized Baseline. Prior to sample analysis, establish
a stable baseline with the detector set at the required attenuation
by setting the eluent and post-column reagent flow rates according
to the manufacturers recommendations.
Note:
As long as the ratio of eluent flow rate to PCR flow rate
remains constant, the standard curve should remain linear. Inject a
sample of reagent water to ensure that no Cr+6 appears in the water
blank.
11.6.4 Sample Injection Loop. Size of injection loop is based on
standard/sample concentrations and the selected attenuator
setting.
11.6.4.1 A 50-µL loop is normally sufficient for most higher
concentrations.
11.6.4.2 The sample volume used to load the injection loop
should be at least 10 times the loop size so that all tubing in
contact with the sample is thoroughly flushed with the new sample
to prevent cross contamination.
11.6.5 IC/PCR Instrument Calibration.
11.6.5.1 First, inject the calibration standards prepared, as
described in Section 7.3.8 to correspond to the appropriate
concentration range, starting with the lowest standard first.
11.6.5.2 Check the performance of the instrument and verify the
calibration using data gathered from analyses of laboratory blanks,
calibration standards, and a quality control sample.
11.6.5.3 Verify the calibration by analyzing a calibration
reference standard. If the measured concentration exceeds the
established value by more than 10 percent, perform a second
analysis. If the measured concentration still exceeds the
established value by more than 10 percent, terminate the analysis
until the problem can be identified and corrected.
11.6.6 IC/PCR Instrument Operation.
11.6.6.1 Inject the calibration reference standard (as described
in Section 9.3.1), followed by the field reagent blank (Section
8.2.4), and the field samples.
11.6.6.1.1 Standards (and QC standards) and samples are injected
into the sample loop of the desired size (use a larger size loop
for greater sensitivity). The Cr+6 is collected on the resin bed of
the column.
11.6.6.1.2 After separation from other sample components, the
Cr+6 forms a specific complex in the post-column reactor with the
DPC reaction solution, and the complex is detected by visible
absorbance at a maximum wavelength of 540 nm.
11.6.6.1.3 The amount of absorbance measured is proportional to
the concentration of the Cr+6 complex formed.
11.6.6.1.4 The IC retention time and the absorbance of the Cr+6
complex with known Cr+6 standards analyzed under identical
conditions must be compared to provide both qualitative and
quantitative analyses.
11.6.6.1.5 If a sample peak appears near the expected retention
time of the Cr+6 ion, spike the sample according to Section 9.3.4
to verify peak identity.
11.6.7 IC/PCR Operational Quality Control Procedures.
11.6.7.1 Samples should be at a pH ≥8.5 for NaOH and ≥8.0 if
using NaHCO3; document any discrepancies.
11.6.7.2 Refrigerated samples should be allowed to equilibrate
to ambient temperature prior to preparation and analysis.
11.6.7.3 Repeat the injection of the calibration standards at
the end of the analytical run to assess instrument drift. Measure
areas or heights of the Cr+6/DPC complex chromatogram peaks.
11.6.7.4 To ensure the precision of the sample injection (manual
or autosampler), the response for the second set of injected
standards must be within 10 percent of the average response.
11.6.7.5 If the 10 percent criteria duplicate injection cannot
be achieved, identify the source of the problem and rerun the
calibration standards.
11.6.7.6 Use peak areas or peak heights from the injections of
calibration standards to generate a linear calibration curve. From
the calibration curve, determine the concentrations of the field
samples.
11.6.8 IC/PCR Sample Dilution.
11.6.8.1 Samples having concentrations higher than the
established calibration range must be diluted into the calibration
range and re-analyzed.
11.6.8.2 If dilutions are performed, the appropriate factors
must be applied to sample measurement results.
11.6.9 Reporting Analytical Results. Results should be reported
in µg Cr+6/mL using three significant figures. Field sample volumes
(mL) must be reported also.
12.0 Data Analysis and Calculations
12.1 Pretest Calculations.
12.1.1 Pretest Protocol (Site Test Plan).
12.1.1.1 The pretest protocol should define and address the test
data quality objectives (DQOs), with all assumptions, that will be
required by the end user (enforcement authority); what data are
needed? why are the data needed? how will the data be used? what
are method detection limits? and what are estimated target analyte
levels for the following test parameters.
12.1.1.1.1 Estimated source concentration for total chromium
and/or Cr+6.
12.1.1.1.2 Estimated minimum sampling time and/or volume
required to meet method detection limit requirements (Appendix B 40
CFR Part 136) for measurement of total chromium and/or Cr+6.
12.1.1.1.3 Demonstrate that planned sampling parameters will
meet DQOs. The protocol must demonstrate that the planned sampling
parameters calculated by the tester will meet the needs of the
source and the enforcement authority.
12.1.1.2 The pre-test protocol should include information on
equipment, logistics, personnel, process operation, and other
resources necessary for an efficient and coordinated test.
12.1.1.3 At a minimum, the pre-test protocol should identify and
be approved by the source, the tester, the analytical laboratory,
and the regulatory enforcement authority. The tester should not
proceed with the compliance testing before obtaining approval from
the enforcement authority.
12.1.2 Post Test Calculations.
12.1.2.1 Perform the calculations, retaining one extra decimal
figure beyond that of the acquired data. Round off figures after
final calculations.
12.1.2.2 Nomenclature.
CS = Concentration of Cr in sample solution, µg Cr/mL. Ccr =
Concentration of Cr in stack gas, dry basis, corrected to standard
conditions, mg/dscm. D = Digestion factor, dimension less. F =
Dilution factor, dimension less. MCr = Total Cr in each sample, µg.
Vad = Volume of sample aliquot after digestion, mL. Vaf = Volume of
sample aliquot after dilution, mL. Vbd = Volume of sample aliquot
submitted to digestion, mL. Vbf = Volume of sample aliquot before
dilution, mL. VmL = Volume of impinger contents plus rinses, mL.
Vm(std) = Volume of gas sample measured by the dry gas meter,
corrected to standard conditions, dscm.
12.1.2.3 Dilution Factor. The dilution factor is the ratio of
the volume of sample aliquot after dilution to the volume before
dilution. This ratio is given by the following equation:
12.1.2.4 Digestion Factor. The digestion factor is the ratio of
the volume of sample aliquot after digestion to the volume before
digestion. This ratio is given by Equation 306-2.
12.1.2.5 Total Cr in Sample. Calculate MCr, the total µg Cr in
each sample, using the following equation:
12.1.2.6 Average Dry Gas Meter Temperature and Average Orifice
Pressure Drop. Same as Method 5.
12.1.2.7 Dry Gas Volume, Volume of Water Vapor, Moisture
Content. Same as Method 5.
12.1.2.8 Cr Emission Concentration (CCr). Calculate CCr, the Cr
concentration in the stack gas, in mg/dscm on a dry basis,
corrected to standard conditions using the following equation:
12.1.2.9 Isokinetic Variation, Acceptable Results. Same as
Method 5.
13.0 Method Performance
13.1 Range. The recommended working range for all of the three
analytical techniques starts at five times the analytical detection
limit (see also Section 13.2.2). The upper limit of all three
techniques can be extended indefinitely by appropriate
dilution.
13.2 Sensitivity.
13.2.1 Analytical Sensitivity. The estimated instrumental
detection limits listed are provided as a guide for an instrumental
limit. The actual method detection limits are sample and instrument
dependent and may vary as the sample matrix varies.
13.2.1.2 ICP Analytical Sensitivity. The minimum estimated
detection limits for ICP, as reported in Method 6010A and the
recently revised Method 6010B of SW-846 (Reference 1), are 7.0 µg
Cr/L and 4.7 µg Cr/L, respectively.
13.2.1.3 GFAAS Analytical Sensitivity. The minimum estimated
detection limit for GFAAS, as reported in Methods 7000A and 7191 of
SW-846 (Reference 1), is 1 µg Cr/L.
13.2.1.4 IC/PCR Analytical Sensitivity. The minimum detection
limit for IC/PCR with a preconcentrator, as reported in Methods
0061 and 7199 of SW-846 (Reference 1), is 0.05 µg Cr+6/L.
1.3.2.1.5 Determination of Detection Limits. The laboratory
performing the Cr+6 measurements must determine the method
detection limit on a quarterly basis using a suitable procedure
such as that found in 40 CFR, Part 136, Appendix B. The
determination should be made on samples in the appropriate alkaline
matrix. Normally this involves the preparation (if applicable) and
consecutive measurement of seven (7) separate aliquots of a sample
with a concentration <5 times the expected detection limit. The
detection limit is 3.14 times the standard deviation of these
results.
13.2.2 In-stack Sensitivity. The in-stack sensitivity depends
upon the analytical detection limit, the volume of stack gas
sampled, the total volume of the impinger absorbing solution plus
the rinses, and, in some cases, dilution or concentration factors
from sample preparation. Using the analytical detection limits
given in Sections 13.2.1.1, 13.2.1.2, and 13.2.1.3; a stack gas
sample volume of 1.7 dscm; a total liquid sample volume of 500 mL;
and the digestion concentration factor of 1/2 for the GFAAS
analysis; the corresponding in-stack detection limits are 0.0014 mg
Cr/dscm to 0.0021 mg Cr/dscm for ICP, 0.00015 mg Cr/dscm for GFAAS,
and 0.000015 mg Cr+6/dscm for IC/PCR with preconcentration.
Note:
It is recommended that the concentration of Cr in the analytical
solutions be at least five times the analytical detection limit to
optimize sensitivity in the analyses. Using this guideline and the
same assumptions for impinger sample volume, stack gas sample
volume, and the digestion concentration factor for the GFAAS
analysis (500 mL,1.7 dscm, and 1/2, respectively), the recommended
minimum stack concentrations for optimum sensitivity are 0.0068 mg
Cr/dscm to 0.0103 mg Cr/dscm for ICP, 0.00074 mg Cr/dscm for GFAAS,
and 0.000074 mg Cr+6/dscm for IC/PCR with preconcentration. If
required, the in-stack detection limits can be improved by either
increasing the stack gas sample volume, further reducing the volume
of the digested sample for GFAAS, improving the analytical
detection limits, or any combination of the three.
13.3 Precision.
13.3.1 The following precision data have been reported for the
three analytical methods. In each case, when the sampling precision
is combined with the reported analytical precision, the resulting
overall precision may decrease.
13.3.2 Bias data is also reported for GFAAS.
13.4 ICP Precision.
13.4.1 As reported in Method 6010B of SW-846 (Reference 1), in
an EPA round-robin Phase 1 study, seven laboratories applied the
ICP technique to acid/distilled water matrices that had been spiked
with various metal concentrates. For true values of 10, 50, and 150
µg Cr/L; the mean reported values were 10, 50, and 149 µg Cr/L; and
the mean percent relative standard deviations were 18, 3.3, and 3.8
percent, respectively.
13.4.2 In another multi laboratory study cited in Method 6010B,
a mean relative standard of 8.2 percent was reported for an aqueous
sample concentration of approximately 3750 µg Cr/L.
13.5 GFAAS Precision. As reported in Method 7191 of SW-846
(Reference 1), in a single laboratory (EMSL), using Cincinnati,
Ohio tap water spiked at concentrations of 19, 48, and 77 µg Cr/L,
the standard deviations were ±0.1, ±0.2, and ±0.8, respectively.
Recoveries at these levels were 97 percent, 101 percent, and 102
percent, respectively.
13.6 IC/PCR Precision. As reported in Methods 0061 and 7199 of
SW-846 (Reference 1), the precision of IC/PCR with sample
preconcentration is 5 to 10 percent. The overall precision for
sewage sludge incinerators emitting 120 ng/dscm of Cr+6 and 3.5
µg/dscm of total Cr was 25 percent and 9 percent, respectively; and
for hazardous waste incinerators emitting 300 ng/dscm of C+6 the
precision was 20 percent.
14.0 Pollution Prevention
14.1 The only materials used in this method that could be
considered pollutants are the chromium standards used for
instrument calibration and acids used in the cleaning of the
collection and measurement containers/labware, in the preparation
of standards, and in the acid digestion of samples. Both reagents
can be stored in the same waste container.
14.2 Cleaning solutions containing acids should be prepared in
volumes consistent with use to minimize the disposal of excessive
volumes of acid.
14.3 To the extent possible, the containers/vessels used to
collect and prepare samples should be cleaned and reused to
minimize the generation of solid waste.
15.0 Waste Management
15.1 It is the responsibility of the laboratory and the sampling
team to comply with all federal, state, and local regulations
governing waste management, particularly the discharge regulations,
hazardous waste identification rules, and land disposal
restrictions; and to protect the air, water, and land by minimizing
and controlling all releases from field operations.
15.2 For further information on waste management, consult The
Waste Management Manual for Laboratory Personnel and Less is Better
- Laboratory Chemical Management for Waste Reduction, available
from the American Chemical Society's Department of Government
Relations and Science Policy, 1155 16th Street NW, Washington, DC
20036.
16.0 References
1. “Test Methods for Evaluating Solid Waste, Physical/Chemical
Methods, SW-846, Third Edition,” as amended by Updates I, II, IIA,
IIB, and III. Document No. 955-001-000001. Available from
Superintendent of Documents, U.S. Government Printing Office,
Washington, DC, November 1986.
2. Cox, X.B., R.W. Linton, and F.E. Butler. Determination of
Chromium Speciation in Environmental Particles - A Multi-technique
Study of Ferrochrome Smelter Dust. Accepted for publication in
Environmental Science and Technology.
3. Same as Section 17.0 of Method 5, References 2, 3, 4, 5, and
7.
4. California Air Resources Board, “Determination of Total
Chromium and Hexavalent Chromium Emissions from Stationary
Sources.” Method 425, September 12, 1990.
5. The Merck Index. Eleventh Edition. Merck & Co., Inc.,
1989.
6. Walpole, R.E., and R.H. Myers. “Probability and Statistics
for Scientists and Engineering.” 3rd Edition. MacMillan Publishing
Co., NewYork, N.Y., 1985.
17.0 Tables, Diagrams, Flowcharts, and Validation Data

Method 306A -
Determination of Chromium Emissions From Decorative and Hard
Chromium Electroplating and Chromium Anodizing Operations Note:
This method does not include all of the specifications
(e.g., equipment and supplies) and procedures (e.g.,
sampling and analytical) essential to its performance. Some
material is incorporated by reference from other methods in 40 CFR
Part 60, Appendix A and in this part. Therefore, to obtain reliable
results, persons using this method should have a thorough knowledge
of at least Methods 5 and 306.
1.0 Scope and Application
1.1 Analyte. Chromium. CAS Number (7440-47-3).
1.2 Applicability.
1.2.1 This method applies to the determination of chromium (Cr)
in emissions from decorative and hard chromium electroplating
facilities, chromium anodizing operations, and continuous chromium
plating at iron and steel facilities. The method is less expensive
and less complex to conduct than Method 306. Correctly applied, the
precision and bias of the sample results should be comparable to
those obtained with the isokinetic Method 306. This method is
applicable for the determination of air emissions under nominal
ambient moisture, temperature, and pressure conditions.
1.2.2 The method is also applicable to electroplating and
anodizing sources controlled by wet scrubbers.
1.3 Data Quality Objectives.
1.3.1 Pretest Protocol.
1.3.1.1 The pretest protocol should define and address the test
data quality objectives (DQOs), with all assumptions, that will be
required by the end user (enforcement authority); what data are
needed? why are the data needed? how will data be used? what are
method detection limits? and what are estimated target analyte
levels for the following test parameters.
1.3.1.1.1 Estimated source concentration for total chromium
and/or Cr+6.
1.3.1.1.2 Estimated minimum sampling time and/or volume required
to meet method detection limit requirements (Appendix B 40 CFR Part
136) for measurement of total chromium and/or Cr+6.
1.3.1.1.3 Demonstrate that planned sampling parameters will meet
DQOs. The protocol must demonstrate that the planned sampling
parameters calculated by the tester will meet the needs of the
source and the enforcement authority.
1.3.1.2 The pre-test protocol should include information on
equipment, logistics, personnel, process operation, and other
resources necessary for an efficient and coordinated performance
test.
1.3.1.3 At a minimum, the pre-test protocol should identify and
be approved by the source, the tester, the analytical laboratory,
and the regulatory enforcement authority. The tester should not
proceed with the compliance testing before obtaining approval from
the enforcement authority.
2.0 Summary of Method
2.1 Sampling.
2.1.1 An emission sample is extracted from the source at a
constant sampling rate determined by a critical orifice and
collected in a sampling train composed of a probe and impingers.
The proportional sampling time at the cross sectional traverse
points is varied according to the stack gas velocity at each point.
The total sample time must be at least two hours.
2.1.2 The chromium emission concentration is determined by the
same analytical procedures described in Method 306:
inductively-coupled plasma emission spectrometry (ICP), graphite
furnace atomic absorption spectrometry (GFAAS), or ion
chromatography with a post-column reactor (IC/PCR).
2.1.2.1 Total chromium samples with high chromium concentrations
(≥35 µg/L) may be analyzed using inductively coupled plasma
emission spectrometry (ICP) at 267.72 nm.
Note:
The ICP analysis is applicable for this method only when the
solution analyzed has a Cr concentration greater than or equal to
35 µg/L or five times the method detection limit as determined
according to Appendix B in 40 CFR Part 136.
2.1.2.2 Alternatively, when lower total chromium concentrations
(<35 µg/L) are encountered, a portion of the alkaline sample
solution may be digested with nitric acid and analyzed by graphite
furnace atomic absorption spectroscopy (GFAAS) at 357.9 nm.
2.1.2.3 If it is desirable to determine hexavalent chromium
(Cr+6) emissions, the samples may be analyzed using an ion
chromatograph equipped with a post-column reactor (IC/PCR) and a
visible wavelength detector. To increase sensitivity for trace
levels of Cr+6, a preconcentration system may be used in
conjunction with the IC/PCR.
3.0 Definitions
3.1 Total Chromium - measured chromium content that
includes both major chromium oxidation states (Cr + 3, Cr + 6).
3.2 May - Implies an optional operation.
3.3 Digestion - The analytical operation involving the
complete (or nearly complete) dissolution of the sample in order to
ensure the complete solubilization of the element (analyte) to be
measured.
3.4 Interferences - Physical, chemical, or spectral
phenomena that may produce a high or low bias in the analytical
result.
3.5 Analytical System - All components of the analytical
process including the sample digestion and measurement
apparatus.
3.6 Sample Recovery - The quantitative transfer of sample
from the collection apparatus to the sample preparation (digestion,
etc.) apparatus. This term should not be confused with analytical
recovery.
4.0 Interferences
4.1 Same as in Method 306, Section 4.0.
5.0 Safety
5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method does not purport to
address all of the safety issues associated with its use. It is the
responsibility of the user to establish appropriate safety and
health practices and to determine the applicability of regulatory
limitations prior to performing this test method.
5.2 Chromium and some chromium compounds have been listed as
carcinogens although Chromium (III) compounds show little or no
toxicity. Chromium is a skin and respiratory irritant.
6.0 Equipment and Supplies Note:
Mention of trade names or specific products does not constitute
endorsement by the Environmental Protection Agency.
6.1 Sampling Train. A schematic of the sampling train is shown
in Figure 306A-1. The individual components of the train are
available commercially, however, some fabrication and assembly are
required.
6.1.1 Probe Nozzle/Tubing and Sheath.
6.1.1.1 Use approximately 6.4-mm ( 1/4-in.) inside diameter (ID)
glass or rigid plastic tubing approximately 20 cm (8 in.) in length
with a short 90 degree bend at one end to form the sampling nozzle.
Grind a slight taper on the nozzle end before making the bend.
Attach the nozzle to flexible tubing of sufficient length to enable
collection of a sample from the stack.
6.1.1.2 Use a straight piece of larger diameter rigid tubing
(such as metal conduit or plastic water pipe) to form a sheath that
begins about 2.5 cm (1 in.) from the 90 ° bend on the nozzle and
encases and supports the flexible tubing.
6.1.2 Type S Pitot Tube. Same as Method 2, Section 6.1 (40 CFR
Part 60, Appendix A).
6.1.3 Temperature Sensor.
6.1.3.1 A thermocouple, liquid-filled bulb thermometer,
bimetallic thermometer, mercury-in-glass thermometer, or other
sensor capable of measuring temperature to within 1.5 percent of
the minimum absolute stack temperature.
6.1.3.2 The temperature sensor shall either be positioned near
the center of the stack, or be attached to the pitot tube as
directed in Section 6.3 of Method 2.
6.1.4 Sample Train Connectors.
6.1.4.1 Use thick wall flexible plastic tubing (polyethylene,
polypropylene, or polyvinyl chloride) ∼ 6.4-mm ( 1/4-in.) to 9.5-mm
( 3/8-in.) ID to connect the train components.
6.1.4.2 A combination of rigid plastic tubing and thin wall
flexible tubing may be used as long as tubing walls do not collapse
when leak-checking the train. Metal tubing cannot be used.
6.1.5 Impingers. Three, one-quart capacity, glass canning jars
with vacuum seal lids, or three Greenburg-Smith (GS) design
impingers connected in series, or equivalent, may be used.
6.1.5.1 One-quart glass canning jar. Three separate jar
containers are required: (1) the first jar contains the absorbing
solution; (2) the second is empty and is used to collect any
reagent carried over from the first container; and (3) the third
contains the desiccant drying agent.
6.1.5.2 Canning Jar Connectors. The jar containers are connected
by leak-tight inlet and outlet tubes installed in the lids of each
container for assembly with the train. The tubes may be made of ∼
6.4 mm ( 1/4-in.) ID glass or rigid plastic tubing. For the inlet
tube of the first impinger, heat the glass or plastic tubing and
draw until the tubing separates. Fabricate the necked tip to form
an orifice tip that is approximately 2.4 mm ( 3/32-in.) ID.
6.1.5.2.1 When assembling the first container, place the orifice
tip end of the tube approximately 4.8 mm ( 3/16-in.) above the
inside bottom of the jar.
6.1.5.2.2 For the second container, the inlet tube need not be
drawn and sized, but the tip should be approximately 25 mm (1 in.)
above the bottom of the jar.
6.1.5.2.3 The inlet tube of the third container should extend to
approximately 12.7 mm ( 1/2-in.) above the bottom of the jar.
6.1.5.2.4 Extend the outlet tube for each container
approximately 50 mm (2 in.) above the jar lid and downward through
the lid, approximately 12.7 mm ( 1/2-in.) beneath the bottom of the
lid.
6.1.5.3 Greenburg-Smith Impingers. Three separate impingers of
the Greenburg-Smith (GS) design as described in Section 6.0 of
Method 5 are required. The first GS impinger shall have a standard
tip (orifice/plate), and the second and third GS impingers shall be
modified by replacing the orifice/plate tube with a 13 mm (
1/2-in.) ID glass tube, having an unrestricted opening located 13
mm ( 1/2-in.) from the bottom of the outer flask.
6.1.5.4 Greenburg-Smith Connectors. The GS impingers shall be
connected by leak-free ground glass “U” tube connectors or by
leak-free non-contaminating flexible tubing. The first impinger
shall contain the absorbing solution, the second is empty and the
third contains the desiccant drying agent.
6.1.6 Manometer. Inclined/vertical type, or equivalent device,
as described in Section 6.2 of Method 2 (40 CFR Part 60, Appendix
A).
6.1.7 Critical Orifice. The critical orifice is a small
restriction in the sample line that is located upstream of the
vacuum pump. The orifice produces a constant sampling flow rate
that is approximately 0.021 cubic meters per minute (m3/min) or
0.75 cubic feet per minute (cfm).
6.1.7.1 The critical orifice can be constructed by sealing a
2.4-mm ( 3/32-in.) ID brass tube approximately 14.3 mm ( 9/16-in.)
in length inside a second brass tube that is approximately 8 mm (
5/16-in.) ID and 14.3-mm ( 9/16-in.) in length .
6.1.7.2 Materials other than brass can be used to construct the
critical orifice as long as the flow through the sampling train can
be maintained at approximately 0.021 cubic meter per minute (0.75)
cfm.
6.1.8 Connecting Hardware. Standard pipe and fittings, 9.5-mm (
3/8-in.), 6.4-mm ( 1/4-in.) or 3.2-mm ( 1/8-in.) ID, may be used to
assemble the vacuum pump, dry gas meter and other sampling train
components.
6.1.9 Vacuum Gauge. Capable of measuring approximately 760 mm Hg
(30 in. Hg) vacuum in 25.4 mm HG (1 in. Hg) increments. Locate
vacuum gauge between the critical orifice and the vacuum pump.
6.1.10 Pump Oiler. A glass oil reservoir with a wick mounted at
the vacuum pump inlet that lubricates the pump vanes. The oiler
should be an in-line type and not vented to the atmosphere. See
EMTIC Guideline Document No. GD-041.WPD for additional
information.
6.1.11 Vacuum Pump. Gast Model 0522-V103-G18DX, or equivalent,
capable of delivering at least 1.5 cfm at 15 in. Hg vacuum.
6.1.12 Oil Trap/Muffler. An empty glass oil reservoir without
wick mounted at the pump outlet to control the pump noise and
prevent oil from reaching the dry gas meter.
6.1.13 By-pass Fine Adjust Valve (Optional). Needle valve
assembly 6.4-mm ( 1/4-in.), Whitey 1 RF 4-A, or equivalent, that
allows for adjustment of the train vacuum.
6.1.13.1 A fine-adjustment valve is positioned in the optional
pump by-pass system that allows the gas flow to recirculate through
the pump. This by-pass system allows the tester to control/reduce
the maximum leak-check vacuum pressure produced by the pump.
6.1.13.1.1 The tester must conduct the post test leak check at a
vacuum equal to or greater than the maximum vacuum encountered
during the sampling run.
6.1.13.1.2 The pump by-pass assembly is not required, but is
recommended if the tester intends to leak-check the 306A train at
the vacuum experienced during a run.
6.1.14 Dry Gas Meter. An Equimeter Model 110 test meter or,
equivalent with temperature sensor(s) installed (inlet/outlet) to
monitor the meter temperature. If only one temperature sensor is
installed, locate the sensor at the outlet side of the meter. The
dry gas meter must be capable of measuring the gaseous volume to
within ±2% of the true volume.
Note:
The Method 306 sampling train is also commercially available and
may be used to perform the Method 306A tests. The sampling train
may be assembled as specified in Method 306A with the sampling rate
being operated at the delta H@ specified for the calibrated orifice
located in the meter box. The Method 306 train is then operated as
described in Method 306A.
6.2 Barometer. Mercury aneroid barometer, or other barometer
equivalent, capable of measuring atmospheric pressure to within
±2.5 mm Hg (0.1 in. Hg).
6.2.1 A preliminary check of the barometer shall be made against
a mercury-in-glass reference barometer or its equivalent.
6.2.2 Tester may elect to obtain the absolute barometric
pressure from a nearby National Weather Service station.
6.2.2.1 The station value (which is the absolute barometric
pressure) must be adjusted for elevation differences between the
weather station and the sampling location. Either subtract 2.5 mm
Hg (0.1 in. Hg) from the station value per 30 m (100 ft) of
elevation increase or add the same for an elevation decrease.
6.2.2.2 If the field barometer cannot be adjusted to agree
within 0.1 in. Hg of the reference barometric, repair or discard
the unit. The barometer pressure measurement shall be recorded on
the sampling data sheet.
6.3 Sample Recovery. Same as Method 5, Section 6.2 (40 CFR Part
60, Appendix A), with the following exceptions:
6.3.1 Probe-Liner and Probe-Nozzle Brushes. Brushes are not
necessary for sample recovery. If a probe brush is used, it must be
non-metallic.
6.3.2 Wash Bottles. Polyethylene wash bottle, for sample
recovery absorbing solution.
6.3.3 Sample Recovery Solution. Use 0.1 N NaOH or 0.1 N NaHCO3,
whichever is used as the impinger absorbing solution, to replace
the acetone.
6.3.4 Sample Storage Containers.
6.3.4.1 Glass Canning Jar. The first canning jar container of
the sampling train may serve as the sample shipping container. A
new lid and sealing plastic wrap shall be substituted for the
container lid assembly.
6.3.4.2 Polyethylene or Glass Containers. Transfer the
Greenburg-Smith impinger contents to precleaned polyethylene or
glass containers. The samples shall be stored and shipped in
250-mL, 500-mL or 1000-mL polyethylene or glass containers with
leak-free, non metal screw caps.
6.3.5 pH Indicator Strip, for Cr +6 Samples. pH indicator
strips, or equivalent, capable of determining the pH of solutions
between the range of 7 and 12, at 0.5 pH increments.
6.3.6 Plastic Storage Containers. Air tight containers to store
silica gel.
6.4 Analysis. Same as Method 306, Section 6.3.
7.0 Reagents and Standards. Note:
Unless otherwise indicated, all reagents shall conform to the
specifications established by the Committee on Analytical Reagents
of the American Chemical Society (ACS reagent grade). Where such
specifications are not available, use the best available grade. It
is recommended, but not required, that reagents be checked by the
appropriate analysis prior to field use to assure that
contamination is below the analytical detection limit for the ICP
or GFAAS total chromium analysis; and that contamination is below
the analytical detection limit for Cr+6 using IC/PCR for direct
injection or, if selected, preconcentration.
7.1 Sampling.
7.1.1 Water. Reagent water that conforms to ASTM Specification
D1193 Type II (incorporated by reference see § 63.14). All
references to water in the method refer to reagent water unless
otherwise specified. It is recommended that water blanks be checked
prior to preparing the sampling reagents to ensure that the Cr
content is less than three (3) times the anticipated detection
limit of the analytical method.
7.1.2 Sodium Hydroxide (NaOH) Absorbing Solution, 0.1 N.
Dissolve 4.0 g of sodium hydroxide in 1 liter of water to obtain a
pH of approximately 8.5.
7.1.3 Sodium Bicarbonate (NaHCO3) Absorbing Solution, 0.1 N.
Dissolve approximately 8.5 g of sodium bicarbonate in 1 liter of
water to obtain a pH of approximately 8.3.
7.1.4 Chromium Contamination.
7.1.4.1 The absorbing solution shall not exceed the QC criteria
noted in Method 306, Section 7.1.1 (≤3 times the instrument
detection limit).
7.1.4.2 When the Cr+6 content in the field samples exceeds the
blank concentration by at least a factor of ten (10), Cr+6 blank
levels ≤10 times the detection limit will be allowed.
Note:
At sources with high concentrations of acids and/or SO2, the
concentration of NaOH or NaHCO3 should be ≥0.5 N to insure that the
pH of the solution remains at or above 8.5 for NaOH and 8.0 for
NaHCO3 during and after sampling.
7.1.3 Desiccant. Silica Gel, 6-16 mesh, indicating type.
Alternatively, other types of desiccants may be used, subject to
the approval of the Administrator.
7.2 Sample Recovery. Same as Method 306, Section 7.2.
7.3 Sample Preparation and Analysis. Same as Method 306, Section
7.3.
7.4 Glassware Cleaning Reagents. Same as Method 306, Section
7.4.
8.0 Sample Collection, Recovery, Preservation, Holding Times,
Storage, and Transport Note:
Prior to sample collection, consideration should be given as to
the type of analysis (Cr+6 or total Cr) that will be performed.
Deciding which analysis will be performed will enable the tester to
determine which appropriate sample recovery and storage procedures
will be required to process the sample.
8.1 Sample Collection.
8.1.1 Pretest Preparation.
8.1.1.1 Selection of Measurement Site. Locate the sampling ports
as specified in Section 11.0 of Method 1 (40 CFR Part 60, Appendix
A).
8.1.1.2 Location of Traverse Points.
8.1.1.2.1 Locate the traverse points as specified in Section
11.0 of Method 1 (40 CFR Part 60, Appendix A). Use a total of 24
sampling points for round ducts and 24 or 25 points for rectangular
ducts. Mark the pitot and sampling probe to identify the sample
traversing points.
8.1.1.2.2 For round ducts less than 12 inches in diameter, use a
total of 16 points.
8.1.1.3 Velocity Pressure Traverse. Perform an initial velocity
traverse before obtaining samples. The Figure 306A-2 data sheet may
be used to record velocity traverse data.
8.1.1.3.1 To demonstrate that the flow rate is constant over
several days of testing, perform complete traverses at the
beginning and end of each day's test effort, and calculate the
deviation of the flow rate for each daily period. The beginning and
end flow rates are considered constant if the deviation does not
exceed 10 percent. If the flow rate exceeds the 10 percent
criteria, either correct the inconsistent flow rate problem, or
obtain the Administrator's approval for the test results.
8.1.1.3.2 Perform traverses as specified in Section 8.0 of
Method 2, but record only the Δp (velocity pressure) values for
each sampling point. If a mass emission rate is desired, stack
velocity pressures shall be recorded before and after each test,
and an average stack velocity pressure determined for the testing
period.
8.1.1.4 Verification of Absence of Cyclonic Flow. Check for
cyclonic flow during the initial traverse to verify that it does
not exist. Perform the cyclonic flow check as specified in Section
11.4 of Method 1 (40 CFR Part 60, Appendix A).
8.1.1.4.1 If cyclonic flow is present, verify that the absolute
average angle of the tangential flow does not exceed 20 degrees. If
the average value exceeds 20 degrees at the sampling location, the
flow condition in the stack is unacceptable for testing.
8.1.1.4.2 Alternative procedures, subject to approval of the
Administrator, e.g., installing straightening vanes to
eliminate the cyclonic flow, must be implemented prior to
conducting the testing.
8.1.1.5 Stack Gas Moisture Measurements. Not required.
Measuring the moisture content is optional when a mass emission
rate is to be calculated.
8.1.1.5.1 The tester may elect to either measure the actual
stack gas moisture during the sampling run or utilize a nominal
moisture value of 2 percent.
8.1.1.5.2 For additional information on determining sampling
train moisture, please refer to Method 4 (40 CFR Part 60, Appendix
A).
8.1.1.6 Stack Temperature Measurements. If a mass emission rate
is to be calculated, a temperature sensor must be placed either
near the center of the stack, or attached to the pitot tube as
described in Section 8.3 of Method 2. Stack temperature
measurements, shall be recorded before and after each test, and an
average stack temperature determined for the testing period.
8.1.1.7 Point Sampling Times. Since the sampling rate of the
train (0.75 cfm) is maintained constant by the critical orifice, it
is necessary to calculate specific sampling times for each traverse
point in order to obtain a proportional sample.
8.1.1.7.1 If the sampling period (3 runs) is to be completed in
a single day, the point sampling times shall be calculated only
once.
8.1.1.7.2 If the sampling period is to occur over several days,
the sampling times must be calculated daily using the initial
velocity pressure data recorded for that day. Determine the average
of the Δp values obtained during the velocity traverse (Figure
306A-2).
8.1.1.7.3 If the stack diameter is less than 12 inches, use 7.5
minutes in place of 5 minutes in the equation and 16 sampling
points instead of 24 or 25 points. Calculate the sampling times for
each traverse point using the following equation:
![]()
Where: n = Sampling point number. Δp = Average
pressure differential across pitot tube, mm H2O (in. H2O). ΔPavg =
Average of Δp values, mm H2O (in. H2O). Note:
Convert the decimal fractions for minutes to seconds.
8.1.1.8 Pretest Preparation. It is recommended, but not
required, that all items which will be in contact with the sample
be cleaned prior to performing the testing to avoid possible sample
contamination (positive chromium bias). These items include, but
are not limited to: Sampling probe, connecting tubing, impingers,
and jar containers.
8.1.1.8.1 Sample train components should be: (1) Rinsed with hot
tap water; (2) washed with hot soapy water; (3) rinsed with tap
water; (4) rinsed with reagent water; (5) soaked in a 10 percent
(v/v) nitric acid solution for at least four hours; and (6) rinsed
throughly with reagent water before use.
8.1.1.8.2 At a minimum, the tester should, rinse the probe,
connecting tubing, and first and second impingers twice with either
0.1 N sodium hydroxide (NaOH) or 0.1 N sodium bicarbonate (NaHCO3)
and discard the rinse solution.
8.1.1.8.3 If separate sample shipping containers are to be used,
these also should be precleaned using the specified cleaning
procedures.
8.1.1.9 Preparation of Sampling Train. Assemble the sampling
train as shown in Figure 306A-1. Secure the nozzle-liner assembly
to the outer sheath to prevent movement when sampling.
8.1.1.9.1 Place 250 mL of 0.1 N NaOH or 0.1 N NaHCO3 absorbing
solution into the first jar container or impinger. The second
jar/impinger is to remain empty. Place 6 to 16 mesh indicating
silica gel, or equivalent desiccant into the third jar/impinger
until the container is half full (∼ 300 to 400 g).
8.1.1.9.2 Place a small cotton ball in the outlet exit tube of
the third jar to collect small silica gel particles that may
dislodge and impair the pump and/or gas meter.
8.1.1.10 Pretest Leak-Check. A pretest leak-check is
recommended, but not required. If the tester opts to conduct the
pretest leak-check, the following procedures shall be performed:
(1) Place the jar/impinger containers into an ice bath and wait 10
minutes for the ice to cool the containers before performing the
leak check and/or start sampling; (2) to perform the leak check,
seal the nozzle using a piece of clear plastic wrap placed over the
end of a finger and switch on the pump; and (3) the train system
leak rate should not exceed 0.02 cfm at a vacuum of 380 mm Hg (15
in. Hg) or greater. If the leak rate does exceed the 0.02 cfm
requirement, identify and repair the leak area and perform the leak
check again.
Note:
Use caution when releasing the vacuum following the leak check.
Always allow air to slowly flow through the nozzle end of the train
system while the pump is still operating. Switching off the pump
with vacuum on the system may result in the silica gel being pulled
into the second jar container.
8.1.1.11 Leak-Checks During Sample Run. If, during the sampling
run, a component (e.g., jar container) exchange becomes necessary,
a leak-check shall be conducted immediately before the
component exchange is made. The leak-check shall be performed
according to the procedure outlined in Section 8.1.1.10 of this
method. If the leakage rate is found to be ≤0.02 cfm at the maximum
operating vacuum, the results are acceptable. If, however, a higher
leak rate is obtained, either record the leakage rate and correct
the sample volume as shown in Section 12.3 of Method 5 or void the
sample and initiate a replacement run. Following the component
change, leak-checks are optional, but are recommended as are the
pretest leak-checks.
8.1.1.12 Post Test Leak Check. Remove the probe assembly and
flexible tubing from the first jar/impinger container. Seal the
inlet tube of the first container using clear plastic wrap and
switch on the pump. The vacuum in the line between the pump and the
critical orifice must be ≥15 in. Hg. Record the vacuum gauge
measurement along with the leak rate observed on the train
system.
8.1.1.12.1 If the leak rate does not exceed 0.02 cfm, the
results are acceptable and no sample volume correction is
necessary.
8.1.1.12.2 If, however, a higher leak rate is obtained (>0.02
cfm), the tester shall either record the leakage rate and correct
the sample volume as shown in Section 12.3 of Method 5, or void the
sampling run and initiate a replacement run. After completing the
leak-check, slowly release the vacuum at the first container while
the pump is still operating. Afterwards, switch-off the pump.
8.1.2 Sample Train Operation.
8.1.2.1 Data Recording. Record all pertinent process and
sampling data on the data sheet (see Figure 306A-3). Ensure that
the process operation is suitable for sample collection.
8.1.2.2 Starting the Test. Place the probe/nozzle into the duct
at the first sampling point and switch on the pump. Start the
sampling using the time interval calculated for the first point.
When the first point sampling time has been completed, move to the
second point and continue to sample for the time interval
calculated for that point; sample each point on the traverse in
this manner. Maintain ice around the sample containers during the
run.
8.1.2.3 Critical Flow. The sample line between the critical
orifice and the pump must operate at a vacuum of ≥380 mm Hg (≥15
in. Hg) in order for critical flow to be maintained. This vacuum
must be monitored and documented using the vacuum gauge located
between the critical orifice and the pump.
Note:
Theoretically, critical flow for air occurs when the ratio of
the orifice outlet absolute pressure to the orifice inlet absolute
pressure is less than a factor of 0.53. This means that the system
vacuum should be at least ≥356 mm Hg (≥14 in. Hg) at sea level and
∼ 305 mm Hg (∼ 12 in. Hg) at higher elevations.
8.1.2.4 Completion of Test.
8.1.2.4.1 Circular Stacks. Complete the first port traverse and
switch off the pump. Testers may opt to perform a leak-check
between the port changes to verify the leak rate however, this is
not mandatory. Move the sampling train to the next sampling port
and repeat the sequence. Be sure to record the final dry gas meter
reading after completing the test run. After performing the post
test leak check, disconnect the jar/impinger containers from the
pump and meter assembly and transport the probe, connecting tubing,
and containers to the sample recovery area.
8.1.2.4.2 Rectangle Stacks. Complete each port traverse as per
the instructions provided in 8.1.2.4.1.
Note:
If an approximate mass emission rate is to be calculated,
measure and record the stack velocity pressure and temperature
before and after the test run.
8.2 Sample Recovery. After the train has been transferred to the
sample recovery area, disconnect the tubing that connects the
jar/impingers. The tester shall select either the total Cr or Cr+6
sample recovery option. Samples to be analyzed for both total Cr
and Cr+6 shall be recovered using the Cr+6 sample option (Section
8.2.2).
Note:
Collect a reagent blank sample for each of the total Cr or the
Cr+6 analytical options. If both analyses (Cr and Cr+6) are to be
conducted on the samples, collect separate reagent blanks for each
analysis. Also, since particulate matter is not usually present at
chromium electroplating and/or chromium anodizing operations, it is
not necessary to filter the Cr+6 samples unless there is observed
sediment in the collected solutions. If it is necessary to filter
the Cr+6 solutions, please refer to Method 0061, Determination of
Hexavalent Chromium Emissions from Stationary Sources, Section 7.4,
Sample Preparation in SW-846 (see Reference 1).
8.2.1 Total Cr Sample Option.
8.2.1.1 Shipping Container No. 1. The first jar container may
either be used to store and transport the sample, or if GS
impingers are used, samples may be stored and shipped in precleaned
250-mL, 500-mL or 1000-mL polyethylene or glass bottles with
leak-free, non-metal screw caps.
8.2.1.1.1 Unscrew the lid from the first jar/impinger
container.
8.2.1.1.2 Lift the inner tube assembly almost out of the
container, and using the wash bottle containing fresh absorbing
solution, rinse the outside of the tube that was immersed in the
container solution; rinse the inside of the tube as well, by
rinsing twice from the top of the tube down through the inner tube
into the container.
8.2.1.2 Recover the contents of the second jar/impinger
container by removing the lid and pouring any contents into the
first shipping container.
8.2.1.2.1 Rinse twice, using fresh absorbing solution, the inner
walls of the second container including the inside and outside of
the inner tube.
8.2.1.2.2 Rinse the connecting tubing between the first and
second sample containers with absorbing solution and place the
rinses into the first container.
8.2.1.3 Position the nozzle, probe and connecting plastic tubing
in a vertical position so that the tubing forms a “U”.
8.2.1.3.1 Using the wash bottle, partially fill the tubing with
fresh absorbing solution. Raise and lower the end of the plastic
tubing several times to allow the solution to contact the internal
surfaces. Do not allow the solution to overflow or part of the
sample will be lost. Place the nozzle end of the probe over the
mouth of the first container and elevate the plastic tubing so that
the solution flows into the sample container.
8.2.1.3.2 Repeat the probe/tubing sample recovery procedure but
allow the solution to flow out the opposite end of the plastic
tubing into the sample container. Repeat the entire sample recovery
procedure once again.
8.2.1.4 Use approximately 200 to 300 mL of the 0.1 N NaOH or 0.1
N NaHCO3 absorbing solution during the rinsing of the probe nozzle,
probe liner, sample containers, and connecting tubing.
8.2.1.5 Place a piece of clear plastic wrap over the mouth of
the sample jar to seal the shipping container. Use a standard lid
and band assembly to seal and secure the sample in the jar.
8.2.1.5.1 Label the jar clearly to identify its contents, sample
number and date.
8.2.1.5.2 Mark the height of the liquid level on the container
to identify any losses during shipping and handling.
8.2.1.5.3 Prepare a chain-of-custody sheet to accompany the
sample to the laboratory.
8.2.2 Cr+6 Sample Option.
8.2.2.1 Shipping Container No. 1. The first jar container may
either be used to store and transport the sample, or if GS
impingers are used, samples may be stored and shipped in precleaned
250-mL, 500-mL or 1000-mL polyethylene or glass bottles with
leak-free non-metal screw caps.
8.2.2.1.1 Unscrew and remove the lid from the first jar
container.
8.2.2.1.2 Measure and record the pH of the solution in the first
container by using a pH indicator strip. The pH of the solution
must be ≥8.5 for NaOH and ≥8.0 for NaHCO3. If not, discard the
collected sample, increase the concentration of the NaOH or NaHCO3
absorbing solution to 0.5 M and collect another air emission
sample.
8.2.2.2 After measuring the pH of the first container, follow
sample recovery procedures described in Sections 8.2.1.1 through
8.2.1.5.
Note:
Since particulate matter is not usually present at chromium
electroplating and/or chromium anodizing facilities, it is not
necessary to filter the Cr+6 samples unless there is observed
sediment in the collected solutions. If it is necessary to filter
the Cr+6 solutions, please refer to the EPA Method 0061,
Determination of Hexavalent Chromium Emissions from Stationary
Sources, Section 7.4, Sample Preparation in SW-846 (see Reference
5) for procedure.
8.2.3 Silica Gel Container. Observe the color of the indicating
silica gel to determine if it has been completely spent and make a
notation of its condition/color on the field data sheet. Do not use
water or other liquids to remove and transfer the silica gel.
8.2.4 Total Cr and/or Cr+6 Reagent Blank.
8.2.4.1 Shipping Container No. 2. Place approximately 500 mL of
the 0.1 N NaOH or 0.1 N NaHCO3 absorbing solution in a precleaned,
labeled sample container and include with the field samples for
analysis.
8.3 Sample Preservation, Storage, and Transport.
8.3.1 Total Cr Option. Samples that are to be analyzed for total
Cr need not be refrigerated.
8.3.2 Cr+6 Option. Samples that are to be analyzed for Cr+6 must
be shipped and stored at 4 °C (∼40 °F).
Note:
Allow Cr+6 samples to return to ambient temperature prior to
analysis.
8.4 Sample Holding Times.
8.4.1 Total Cr Option. Samples that are to be analyzed for total
chromium must be analyzed within 60 days of collection.
8.4.2 Cr+6 Option. Samples that are to be analyzed for Cr+6 must
be analyzed within 14 days of collection.
9.0 Quality Control
9.1 Same as Method 306, Section 9.0.
10.0 Calibration and Standardization Note:
Tester shall maintain a performance log of all calibration
results.
10.1 Pitot Tube. The Type S pitot tube assembly shall be
calibrated according to the procedures outlined in Section 10.1 of
Method 2.
10.2 Temperature Sensor. Use the procedure in Section 10.3 of
Method 2 to calibrate the in-stack temperature sensor.
10.3 Metering System.
10.3.1 Sample Train Dry Gas Meter Calibration. Calibrations may
be performed as described in Section 16.2 of Method 5 by either the
manufacturer, a firm who provides calibration services, or the
tester.
10.3.2 Dry Gas Meter Calibration Coefficient (Ym). The meter
calibration coefficient (Ym) must be determined prior to the
initial use of the meter, and following each field test program. If
the dry gas meter is new, the manufacturer will have specified the
Ym value for the meter. This Ym value can be used as the pretest
value for the first test. For subsequent tests, the tester must use
the Ym value established during the pretest calibration.
10.3.3 Calibration Orifice. The manufacturer may have included a
calibration orifice and a summary spreadsheet with the meter that
may be used for calibration purposes. The spreadsheet will provide
data necessary to determine the calibration for the orifice and
meter (standard cubic feet volume, sample time, etc.). These data
were produced when the initial Ym value was determined for the
meter.
10.3.4 Ym Meter Value Verification or Meter Calibration.
10.3.4.1 The Ym meter value may be determined by replacing the
sampling train critical orifice with the calibration orifice.
Replace the critical orifice assembly by installing the calibration
orifice in the same location. The inlet side of the calibration
orifice is to be left open to the atmosphere and is not to
be reconnected to the sample train during the calibration
procedure.
10.3.4.2 If the vacuum pump is cold, switch on the pump and
allow it to operate (become warm) for several minutes prior to
starting the calibration. After stopping the pump, record the
initial dry gas meter volume and meter temperature.
10.3.4.3 Perform the calibration for the number of minutes
specified by the manufacturer's data sheet (usually 5 minutes).
Stop the pump and record the final dry gas meter volume and
temperature. Subtract the start volume from the stop volume to
obtain the Vm and average the meter temperatures (tm).
10.3.5 Ym Value Calculation. Ym is the calculated value for the
dry gas meter. Calculate Ym using the following equation:
![]()
Where: Pbar = Barometric pressure at meter, mm
Hg, (in. Hg). Pstd = Standard absolute pressure, Metric = 760 mm
Hg. English = 29.92 in. Hg. tm = Average dry gas meter temperature,
°C, (°F). Tm = Absolute average dry gas meter temperature, Metric
°K = 273 + tm (°C). English °R = 460 + tm (°F). Tstd = Standard
absolute temperature, Metric = 293 °K. English = 528 °R. Vm =
Volume of gas sample as measured (actual) by dry gas meter,
dcm,(dcf). Vm(std),mfg = Volume of gas sample measured by
manufacture's calibrated orifice and dry gas meter, corrected to
standard conditions (pressure/temperature) dscm (dscf). Ym = Dry
gas meter calibration factor, (dimensionless).
10.3.6 Ym Comparison. Compare the Ym value provided by the
manufacturer (Section 10.3.3) or the pretest Ym value to the post
test Ym value using the following equation:
10.3.6.1 If this ratio is between 0.95 and 1.05, the designated
Ym value for the meter is acceptable for use in later
calculations.
10.3.6.1.1 If the value is outside the specified range, the test
series shall either be: 1) voided and the samples discarded; or 2)
calculations for the test series shall be conducted using whichever
meter coefficient value (i.e., manufacturers's/pretest Ym value or
post test Ym value) produces the lowest sample volume.
10.3.6.1.2 If the post test dry gas meter Ym value differs by
more than 5% as compared to the pretest value, either perform the
calibration again to determine acceptability or return the meter to
the manufacturer for recalibration.
10.3.6.1.3 The calibration may also be conducted as specified in
Section 10.3 or Section 16.0 of Method 5 (40 CFR Part 60, Appendix
A), except that it is only necessary to check the calibration at
one flow rate of ∼ 0.75 cfm.
10.3.6.1.4 The calibration of the dry gas meter must be verified
after each field test program using the same procedures.
Note:
The tester may elect to use the Ym post test value for the next
pretest Ym value; e.g., Test 1 post test Ym value and Test 2
pretest Ym value would be the same.
10.4 Barometer. Calibrate against a mercury barometer that has
been corrected for temperature and elevation.
10.5 ICP Spectrometer Calibration. Same as Method 306, Section
10.2.
10.6 GFAA Spectrometer Calibration. Same as Method 306, Section
10.3.
10.7 IC/PCR Calibration. Same as Method 306, Section 10.4.
11.0 Analytical Procedures Note:
The method determines the chromium concentration in µg Cr/mL. It
is important that the analyst measure the volume of the field
sample prior to analyzing the sample. This will allow for
conversion of µg Cr/mL to µg Cr/sample.
11.1 Analysis. Refer to Method 306 for sample preparation and
analysis procedures.
12.0 Data Analysis and Calculations
12.1 Calculations. Perform the calculations, retaining one extra
decimal point beyond that of the acquired data. When reporting
final results, round number of figures consistent with the original
data.
12.2 Nomenclature.
A = Cross-sectional area of stack, m2 (ft2). Bws = Water vapor in
gas stream, proportion by volume, dimensionless (assume 2 percent
moisture = 0.02). Cp = Pitot tube coefficient; “S” type pitot
coefficient usually 0.840, dimensionless. CS = Concentration of Cr
in sample solution, µg Cr/mL. CCr = Concentration of Cr in stack
gas, dry basis, corrected to standard conditions µg/dscm (gr/dscf).
d = Diameter of stack, m (ft). D = Digestion factor, dimensionless.
ER = Approximate mass emission rate, mg/hr (lb/hr). F = Dilution
factor, dimensionless. L = Length of a square or rectangular duct,
m (ft). MCr = Total Cr in each sample, µg (gr). Ms = Molecular
weight of wet stack gas, wet basis, g/g-mole, (lb/lb-mole); in a
nominal gas stream at 2% moisture the value is 28.62. Pbar =
Barometric pressure at sampling site, mm Hg (in. Hg). Ps = Absolute
stack gas pressure; in this case, usually the same value as the
barometric pressure, mm Hg (in. Hg). Pstd = Standard absolute
pressure: Metric = 760 mm Hg. English = 29.92 in. Hg. Qstd =
Average stack gas volumetric flow, dry, corrected to standard
conditions, dscm/hr (dscf/hr). tm = Average dry gas meter
temperature, °C (°F). Tm = Absolute average dry gas meter
temperature: Metric °K = 273 + tm (°C). English °R = 460 + tm (°F).
ts = Average stack temperature, °C (°F). Ts = Absolute average
stack gas temperature: Metric °K = 273 + ts (°C). English °R = 460
+ ts (°F). Tstd = Standard absolute temperature: Metric = 293 °K.
English = 528 °R. Vad = Volume of sample aliquot after digestion
(mL). Vaf = Volume of sample aliquot after dilution (mL). Vbd =
Volume of sample aliquot submitted to digestion (mL). Vbf = Volume
of sample aliquot before dilution (mL). Vm = Volume of gas sample
as measured (actual, dry) by dry gas meter, dcm (dcf). VmL = Volume
of impinger contents plus rinses (mL). Vm(std) = Volume of gas
sample measured by the dry gas meter, corrected to standard
conditions (temperature/pressure), dscm (dscf). vs = Stack gas
average velocity, calculated by Method 2, Equation 2-9, m/sec
(ft/sec). W = Width of a square or rectangular duct, m (ft). Ym =
Dry gas meter calibration factor, (dimensionless). Δp = Velocity
head measured by the Type S pitot tube, cm H2O (in. H2O). Δpavg =
Average of Δp values, mm H2O (in. H2O).
12.3 Dilution Factor. The dilution factor is the ratio of the
volume of sample aliquot after dilution to the volume before
dilution. The dilution factor is usually calculated by the
laboratory. This ratio is derived by the following equation:
12.4 Digestion Factor. The digestion factor is the ratio of the
volume of sample aliquot after digestion to the volume before
digestion. The digestion factor is usually calculated by the
laboratory. This ratio is derived by the following equation.
12.5 Total Cr in Sample. Calculate MCr, the total µg Cr in each
sample, using the following equation:
12.6 Dry Gas Volume. Correct the sample volume measured by the
dry gas meter to standard conditions (20 °C, 760 mm Hg or 68 °F,
29.92 in. Hg) using the following equation:
![]()
Where: K1 = Metric units - 0.3855 °K/mm Hg.
English units - 17.64 °R/in. Hg.
12.7 Cr Emission Concentration (CCr). Calculate CCr, the Cr
concentration in the stack gas, in µg/dscm (µg/dscf) on a dry
basis, corrected to standard conditions, using the following
equation:
![]()
Note:
To convert µg/dscm (µg/dscf) to mg/dscm (mg/dscf), divide by
1000.
12.8 Stack Gas Velocity.
12.8.1 Kp = Velocity equation constant:
12.8.2 Average Stack Gas Velocity.
12.9 Cross sectional area of stack.
12.10 Average Stack Gas Dry Volumetric Flow Rate.
Note:
The emission rate may be based on a nominal stack moisture
content of 2 percent (0.02). To calculate an emission rate, the
tester may elect to use either the nominal stack gas moisture value
or the actual stack gas moisture collected during the sampling
run.
Volumetric Flow Rate Equation:
![]()
Where: 3600 = Conversion factor, sec/hr.
![]()
Note:
To convert Qstd from dscm/hr (dscf/hr) to dscm/min (dscf/min),
divide Qstd by 60.
12.11 Mass emission rate, mg/hr (lb/hr):
![]()
13.0 Method Performance
13.1 Range. The recommended working range for all of the three
analytical techniques starts at five times the analytical detection
limit (see also Method 306, Section 13.2.2). The upper limit of all
three techniques can be extended indefinitely by appropriate
dilution.
13.2 Sensitivity.
13.2.1 Analytical Sensitivity. The estimated instrumental
detection limits listed are provided as a guide for an instrumental
limit. The actual method detection limits are sample and instrument
dependent and may vary as the sample matrix varies.
13.2.1.1 ICP Analytical Sensitivity. The minimum estimated
detection limits for ICP, as reported in Method 6010A and the
recently revised Method 6010B of SW-846 (Reference 1), are 7.0 µg
Cr/L and 4.7 µg Cr/L, respectively.
13.2.1.2 GFAAS Analytical Sensitivity. The minimum estimated
detection limit for GFAAS, as reported in Methods 7000A and 7191 of
SW-846 (Reference 1), is 1.0 µg Cr/L.
13.2.1.3 IC/PCR Analytical Sensitivity. The minimum detection
limit for IC/PCR with a preconcentrator, as reported in Methods
0061 and 7199 of SW-846 (Reference 1), is 0.05 µg Cr+6/L.
13.2.2 In-stack Sensitivity. The in-stack sensitivity depends
upon the analytical detection limit, the volume of stack gas
sampled, and the total volume of the impinger absorbing solution
plus the rinses. Using the analytical detection limits given in
Sections 13.2.1.1, 13.2.1.2, and 13.2.1.3; a stack gas sample
volume of 1.7 dscm; and a total liquid sample volume of 500 mL; the
corresponding in-stack detection limits are 0.0014 mg Cr/dscm to
0.0021 mg Cr/dscm for ICP, 0.00029 mg Cr/dscm for GFAAS, and
0.000015 mg Cr+36/dscm for IC/PCR with preconcentration.
Note:
It is recommended that the concentration of Cr in the analytical
solutions be at least five times the analytical detection limit to
optimize sensitivity in the analyses. Using this guideline and the
same assumptions for impinger sample volume and stack gas sample
volume (500 mL and 1.7 dscm, respectively), the recommended minimum
stack concentrations for optimum sensitivity are 0.0068 mg Cr/dscm
to 0.0103 mg Cr/dscm for ICP, 0.0015 mg Cr/dscm for GFAAS, and
0.000074 mg Cr+6 dscm for IC/PCR with preconcentration. If
required, the in-stack detection limits can be improved by either
increasing the sampling time, the stack gas sample volume, reducing
the volume of the digested sample for GFAAS, improving the
analytical detection limits, or any combination of the three.
13.3 Precision.
13.3.1 The following precision data have been reported for the
three analytical methods. In each case, when the sampling precision
is combined with the reported analytical precision, the resulting
overall precision may decrease.
13.3.2 Bias data is also reported for GFAAS.
13.4 ICP Precision.
13.4.1 As reported in Method 6010B of SW-846 (Reference 1), in
an EPA round-robin Phase 1 study, seven laboratories applied the
ICP technique to acid/distilled water matrices that had been spiked
with various metal concentrates. For true values of 10, 50, and 150
µg Cr/L; the mean reported values were 10, 50, and 149 µg Cr/L; and
the mean percent relative standard deviations were 18, 3.3, and 3.8
percent, respectively.
13.4.2 In another multilaboratory study cited in Method 6010B, a
mean relative standard of 8.2 percent was reported for an aqueous
sample concentration of approximately 3750 µg Cr/L.
13.5 GFAAS Precision. As reported in Method 7191 of SW-846
(Reference 1), in a single laboratory (EMSL), using Cincinnati,
Ohio tap water spiked at concentrations of 19, 48, and 77 µg Cr/L,
the standard deviations were ±0.1, ±0.2, and ±0.8, respectively.
Recoveries at these levels were 97 percent, 101 percent, and 102
percent, respectively.
13.6 IC/PCR Precision. As reported in Methods 0061 and 7199 of
SW-846 (Reference 1), the precision of IC/PCR with sample
preconcentration is 5 to 10 percent; the overall precision for
sewage sludge incinerators emitting 120 ng/dscm of Cr+6 and 3.5
µg/dscm of total Cr is 25 percent and 9 percent, respectively; and
for hazardous waste incinerators emitting 300 ng/dscm of Cr+6 the
precision is 20 percent.
14.0 Pollution Prevention
14.1 The only materials used in this method that could be
considered pollutants are the chromium standards used for
instrument calibration and acids used in the cleaning of the
collection and measurement containers/labware, in the preparation
of standards, and in the acid digestion of samples. Both reagents
can be stored in the same waste container.
14.2 Cleaning solutions containing acids should be prepared in
volumes consistent with use to minimize the disposal of excessive
volumes of acid.
14.3 To the extent possible, the containers/vessels used to
collect and prepare samples should be cleaned and reused to
minimize the generation of solid waste.
15.0 Waste Management
15.1 It is the responsibility of the laboratory and the sampling
team to comply with all federal, state, and local regulations
governing waste management, particularly the discharge regulations,
hazardous waste identification rules, and land disposal
restrictions; and to protect the air, water, and land by minimizing
and controlling all releases from field operations.
15.2 For further information on waste management, consult The
Waste Management Manual for Laboratory Personnel and Less is
Better-Laboratory Chemical Management for Waste Reduction,
available from the American Chemical Society's Department of
Government Relations and Science Policy, 1155 16th Street NW,
Washington, DC 20036.
16.0 References
1. F.R. Clay, Memo, Impinger Collection Efficiency - Mason Jars
vs. Greenburg-Smith Impingers, Dec. 1989.
2. Segall, R.R., W.G. DeWees, F.R. Clay, and J.W. Brown.
Development of Screening Methods for Use in Chromium Emissions
Measurement and Regulations Enforcement. In: Proceedings of the
1989 EPA/A&WMA International Symposium-Measurement of Toxic and
Related Air Pollutants, A&WMA Publication VIP-13, EPA Report
No. 600/9-89-060, p. 785.
3. Clay, F.R., Chromium Sampling Method. In: Proceedings of the
1990 EPA/A&WMA International Symposium-Measurement of Toxic and
Related Air Pollutants, A&WMA Publication VIP-17, EPA Report
No. 600/9-90-026, p. 576.
4. Clay, F.R., Proposed Sampling Method 306A for the
Determination of Hexavalent Chromium Emissions from Electroplating
and Anodizing Facilities. In: Proceedings of the 1992 EPA/A&WMA
International Symposium-Measurement of Toxic and Related Air
Pollutants, A&WMA Publication VIP-25, EPA Report No.
600/R-92/131, p. 209.
5. Test Methods for Evaluating Solid Waste, Physical/Chemical
Methods, SW-846, Third Edition as amended by Updates I, II, IIA,
IIB, and III. Document No. 955-001-000001. Available from
Superintendent of Documents, U.S. Government Printing Office,
Washington, DC, November 1986.
17.0 Tables, Diagrams, Flowcharts, and Validation Data

Method 306B -
Surface Tension Measurement for Tanks Used at Decorative Chromium
Electroplating and Chromium Anodizing Facilities Note:
This method does not include all of the specifications
(e.g., equipment and supplies) and procedures (e.g.,
sampling and analytical) essential to its performance. Some
material is incorporated by reference from other methods in 40 CFR
Part 60, Appendix A and in this part. Therefore, to obtain reliable
results, persons using this method should have a thorough knowledge
of at least Methods 5 and 306.
1.0 Scope and Application
1.1 Analyte. Not applicable.
1.2 Applicability. This method is applicable to all chromium
electroplating and chromium anodizing operations, and continuous
chromium plating at iron and steel facilities where a wetting agent
is used in the tank as the primary mechanism for reducing emissions
from the surface of the plating solution.
2.0 Summary of Method
2.1 During an electroplating or anodizing operation, gas bubbles
generated during the process rise to the surface of the liquid and
burst. Upon bursting, tiny droplets of chromic acid become
entrained in ambient air. The addition of a wetting agent to the
tank bath reduces the surface tension of the liquid and diminishes
the formation of these droplets.
2.2 This method determines the surface tension of the bath using
a stalagmometer or a tensiometer to confirm that there is
sufficient wetting agent present.
3.0 Definitions [Reserved] 4.0 Interferences [Reserved] 5.0 Safety
5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of
the safety problems associated with its use. It is the
responsibility of the user to establish appropriate safety and
health practices and to determine the applicability of regulatory
limitations prior to performing this test method.
6.0 Equipment and Supplies
6.1 Stalagmometer. Any commercially available stalagmometer or
equivalent surface tension measuring device may be used to measure
the surface tension of the plating or anodizing tank liquid
provided the procedures specified in Section 11.1.2 are
followed.
6.2 Tensiometer. A tensiometer may be used to measure the
surface tension of the tank liquid provided the procedures
specified in ASTM Method D 1331-89, Standard Test Methods for
Surface and Interfacial Tension of Solutions of Surface Active
Agents (incorporated by reference - see § 63.14) are followed.
7.0 Reagents and Standards [Reserved] 8.0 Sample Collection, Sample
Recovery, Sample Preservation, Sample Holding Times, Storage, and
Transport [Reserved] 9.0 Quality Control [Reserved] 10.0
Calibration and Standardization [Reserved] 11.0 Analytical
Procedure
11.1 Procedure. The surface tension of the tank bath may be
measured using a tensiometer, stalagmometer, or any other
equivalent surface tension measuring device for measuring surface
tension in dynes per centimeter.
11.1.1 If a tensiometer is used, the procedures specified in
ASTM Method D 1331-89 must be followed.
11.1.2 If a stalagmometer is used, the procedures specified in
Sections 11.1.2.1 through 11.1.2.3 must be followed.
11.1.2.1 Check the stalagmometer for visual signs of damage. If
the stalagmometer appears to be chipped, cracked, or otherwise in
disrepair, the instrument shall not be used.
11.1.2.2 Using distilled or deionized water and following the
procedures provided by the manufacturer, count the number of drops
corresponding to the distilled/deionized water liquid volume
between the upper and lower etched marks on the stalagmometer. If
the number of drops for the distilled/deionized water is not within
±1 drop of the number indicated on the instrument, the
stalagmometer must be cleaned, using the procedures specified in
Section 11.1.3 of this method, before using the instrument to
measure the surface tension of the tank liquid.
11.1.2.2.1 If the stalagmometer must be cleaned, as indicated in
Section 11.1.2.2, repeat the procedure specified in Section
11.1.2.2 before proceeding.
11.1.2.2.2 If, after cleaning and performing the procedure in
Section 11.1.2.2, the number of drops indicated for the
distilled/deionized water is not within ±1 drop of the number
indicated on the instrument, either use the number of drops
corresponding to the distilled/deionized water volume as the
reference number of drops, or replace the instrument.
11.1.2.3 Determine the surface tension of the tank liquid using
the procedures specified by the manufacturer of the
stalagmometer.
11.1.3 Stalagmometer cleaning procedures. The procedures
specified in Sections 11.1.3.1 through 11.1.3.10 shall be used for
cleaning a stalagmometer, as required by Section 11.1.2.2.
11.1.3.1 Set up the stalagmometer on its stand in a fume
hood.
11.1.3.2 Place a clean 150 (mL) beaker underneath the
stalagmometer and fill the beaker with reagent grade concentrated
nitric acid.
11.1.3.3 Immerse the bottom tip of the stalagmometer
(approximately 1 centimeter (0.5 inches)) into the beaker.
11.1.3.4 Squeeze the rubber bulb and pinch at the arrow up (1)
position to collapse.
11.1.3.5 Place the bulb end securely on top end of stalagmometer
and carefully draw the nitric acid by pinching the arrow up (1)
position until the level is above the top etched line.
11.1.3.6 Allow the nitric acid to remain in stalagmometer for 5
minutes, then carefully remove the bulb, allowing the acid to
completely drain.
11.1.3.7 Fill a clean 150 mL beaker with distilled or deionized
water.
11.1.3.8 Using the rubber bulb per the instructions in Sections
11.1.3.4 and 11.1.3.5, rinse and drain stalagmometer with deionized
or distilled water.
11.1.3.9 Fill a clean 150 mL beaker with isopropyl alcohol.
11.1.3.10 Again using the rubber bulb per the instructions in
Sections 11.1.3.4 and 11.1.3.5, rinse and drain stalagmometer twice
with isopropyl alcohol and allow the stalagmometer to dry
completely.
11.2 Frequency of Measurements.
11.2.1 Measurements of the bath surface tension are performed
using a progressive system which decreases the frequency of surface
tension measurements required when the proper surface tension is
maintained.
11.2.1.1 Initially, following the compliance date, surface
tension measurements must be conducted once every 4 hours of tank
operation for the first 40 hours of tank operation.
11.2.1.2 Once there are no exceedances during a period of 40
hours of tank operation, measurements may be conducted once every 8
hours of tank operation.
11.2.1.3 Once there are no exceedances during a second period of
40 consecutive hours of tank operation, measurements may be
conducted once every 40 hours of tank operation on an on-going
basis, until an exceedance occurs. The maximum time interval for
measurements is once every 40 hours of tank operation.
11.2.2 If a measurement of the surface tension of the solution
is above the 40 dynes per centimeter limit when measured using a
stalagmometer, above 33 dynes per centimeter when measured using a
tensiometer, or above an alternate surface tension limit
established during the performance test, the time interval shall
revert back to the original monitoring schedule of once every 4
hours. A subsequent decrease in frequency would then be allowed
according to Section 11.2.1.
12.0 Data Analysis and Calculations
12.1 Log Book of Surface Tension Measurements and Fume
Suppressant Additions.
12.1.1 The surface tension of the plating or anodizing tank bath
must be measured as specified in Section 11.2.
12.1.2 The measurements must be recorded in the log book. In
addition to the record of surface tension measurements, the
frequency of fume suppressant maintenance additions and the amount
of fume suppressant added during each maintenance addition must be
recorded in the log book.
12.1.3 The log book will be readily available for inspection by
regulatory personnel.
12.2 Instructions for Apparatus Used in Measuring Surface
Tension.
12.2.1 Included with the log book must be a copy of the
instructions for the apparatus used for measuring the surface
tension of the plating or anodizing bath.
12.2.2 If a tensiometer is used, a copy of ASTM Method D 1331-89
must be included with the log book.
13.0 Method Performance [Reserved] 14.0 Pollution Prevention
[Reserved] 15.0 Waste Management [Reserved] 16.0 References
[Reserved] 17.0 Tables, Diagrams, Flowcharts, and Validation Data
[Reserved] Method 307 - Determination of Emissions From Halogenated
Solvent Vapor Cleaning Machines Using a Liquid Level Procedure 1.
Applicability and Principle
1.1 Applicability. This method is applicable to the
determination of the halogenated solvent emissions from solvent
vapor cleaners in the idling mode.
1.2 Principle. The solvent level in the solvent cleaning machine
is measured using inclined liquid level indicators. The change in
liquid level corresponds directly to the amount of solvent lost
from the solvent cleaning machine.
2. Apparatus Note:
Mention of trade names or specific products does not constitute
endorsement by the Environmental Protection Agency.
2.1 Inclined Liquid Level Indicator. A schematic of the inclined
liquid level indicators used in this method is shown in figure
307-1; two inclined liquid level indicators having 0.05 centimeters
divisions or smaller shall be used. The liquid level indicators
shall be made of glass, Teflon, or any similar material that will
not react with the solvent being used. A 6-inch by 1-inch slope is
recommended; however the slope may vary depending on the size and
design of the solvent cleaning machine.
Note:
It is important that the inclined liquid level indicators be
constructed with ease of reading in mind. The inclined liquid level
indicators should also be mounted so that they can be raised or
lowered if necessary to suit the solvent cleaning machine size.
2.2 Horizontal Indicator. Device to check the inclined liquid
level indicators orientation relative to horizontal.
2.3 Velocity Meter. Hotwire and vane anemometers, or other
devices capable of measuring the flow rates ranging from 0 to 15.2
meters per minute across the solvent cleaning machine.
3. Procedure
3.1 Connection of the Inclined Liquid Level Indicator. Connect
one of the inclined liquid level indicators to the boiling sump
drain and the other inclined liquid level indicator to the
immersion sump drain using Teflon tubing and the appropriate
fittings. A schematic diagram is shown in figure 307-2.
3.2 Positioning of Velocity Meter. Position the velocity meter
so that it measures the flow rate of the air passing directly
across the solvent cleaning machine.
3.3 Level the Inclined Liquid Level Indicators.
3.4 Initial Inclined Liquid Level Indicator Readings. Open the
sump drainage valves. Allow the solvent cleaning machine to operate
long enough for the vapor zone to form and the system to stabilize
(check with manufacturer). Record the inclined liquid level
indicators readings and the starting time on the data sheet. A
sample data sheet is provided in figure 307-3.
Date Run Solvent type Solvent density, g/m 3 (lb/ft 3) Length of
boiling sump (SB), m (ft) Width of boiling sump (WB), m (ft) Length
of immersion sump (SI), m (ft) Width of immersion sump (WI), m (ft)
Length of solvent vapor/air interface (SV), m (ft) ______ Width of
solvent vapor/air interface (WV), m (ft) ______
Clock time |
Boiling sump reading |
Immersion sump reading |
Flow rate reading |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Figure 307-3. Data sheet.
3.5 Final Inclined Liquid Level Indicator Readings. At the end
of the 16-hour test run, check to make sure the inclined liquid
level indicators are level; if not, make the necessary adjustments.
Record the final inclined liquid level indicators readings and
time.
3.6 Determination of Solvent Vapor/Air Interface Area for Each
Sump. Determine the area of the solvent/air interface of the
individual sumps. Whenever possible, physically measure these
dimensions, rather than using factory specifications. A schematic
of the dimensions of a solvent cleaning machine is provided in
figure 307-4.

4.
Calculations
4.1 Nomenclature.
AB = area of boiling sump interface, m 2 (ft 2). AI = area of
immersion sump interface, m 2 (ft 2). AV = area of solvent/air
interface, m 2 (ft 2). E = emission rate, kg/m 2-hr (lb/ft 2-hr). K
= 100,000 cm . g/m . kg for metric units. = 12 in./ft for English
units. LBF = final boiling sump inclined liquid level indicators
reading, cm (in.). LBi = initial boiling sump inclined liquid level
indicators reading, cm (in.). LIf = final immersion sump inclined
liquid level indicators reading, cm (in.). LIi = initial immersion
sump inclined liquid level indicators reading, cm (in.). SB =
length of the boiling sump, m (ft). SI = length of the immersion
sump, m (ft). SV = length of the solvent vapor/air interface, m
(ft). WB = width of the boiling sump, m (ft). WI = width of the
immersion sump, m (ft). WV = width of the solvent vapor/air
interface, m (ft). ρ = density of solvent, g/m3 (lb/ft3). θ = test
time, hr.
4.2 Area of Sump Interfaces. Calculate the areas of the boiling
and immersion sump interfaces as follows:
AB = SB WB Eq. 307-1 AI = SI WI Eq. 307-2
4.3 Area of Solvent/Air Interface. Calculate the area of the
solvent vapor/air interface as follows:
AV = SV WV Eq. 307-3
4.4 Emission Rate. Calculate the emission rate as follows:
![]()
Method 308 - Procedure for Determination of
Methanol Emission From Stationary Sources 1.0 Scope and Application
1.1 Analyte. Methanol. Chemical Abstract Service (CAS) No.
67-56-1.
1.2 Applicability. This method applies to the measurement of
methanol emissions from specified stationary sources.
2.0 Summary of Method
A gas sample is extracted from the sampling point in the stack.
The methanol is collected in deionized distilled water and adsorbed
on silica gel. The sample is returned to the laboratory where the
methanol in the water fraction is separated from other organic
compounds with a gas chromatograph (GC) and is then measured by a
flame ionization detector (FID). The fraction adsorbed on silica
gel is extracted with deionized distilled water and is then
separated and measured by GC/FID.
3.0 Definitions [Reserved] 4.0 Interferences [Reserved] 5.0 Safety
5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method does not purport to
address all of the safety problems associated with its use. It is
the responsibility of the user of this test method to establish
appropriate safety and health practices and to determine the
applicability of regulatory limitations before performing this test
method.
5.2 Methanol Characteristics. Methanol is flammable and a
dangerous fire and explosion risk. It is moderately toxic by
ingestion and inhalation.
6.0 Equipment and Supplies
6.1 Sample Collection. The following items are required for
sample collection:
6.1.1 Sampling Train. The sampling train is shown in Figure
308-1 and component parts are discussed below.
6.1.1.1 Probe. Teflon ®, approximately 6-millimeter (mm) (0.24
inch) outside diameter.
6.1.1.2 Impinger. A 30-milliliter (ml) midget impinger. The
impinger must be connected with leak-free glass connectors.
Silicone grease may not be used to lubricate the connectors.
6.1.1.3 Adsorbent Tube. Glass tubes packed with the required
amount of the specified adsorbent.
6.1.1.4 Valve. Needle valve, to regulate sample gas flow
rate.
6.1.1.5 Pump. Leak-free diaphragm pump, or equivalent, to pull
gas through the sampling train. Install a small surge tank between
the pump and rate meter to eliminate the pulsation effect of the
diaphragm pump on the rotameter.
6.1.1.6 Rate Meter. Rotameter, or equivalent, capable of
measuring flow rate to within 2 percent of the selected flow rate
of up to 1000 milliliter per minute (ml/min). Alternatively, the
tester may use a critical orifice to set the flow rate.
6.1.1.7 Volume Meter. Dry gas meter (DGM), sufficiently accurate
to measure the sample volume to within 2 percent, calibrated at the
selected flow rate and conditions actually encountered during
sampling, and equipped with a temperature sensor (dial thermometer,
or equivalent) capable of measuring temperature accurately to
within 3 °C (5.4 °F).
6.1.1.8 Barometer. Mercury (Hg), aneroid, or other barometer
capable of measuring atmospheric pressure to within 2.5 mm (0.1
inch) Hg. See the NOTE in Method 5 (40 CFR part 60, appendix A),
section 6.1.2.
6.1.1.9 Vacuum Gauge and Rotameter. At least 760-mm (30-inch) Hg
gauge and 0- to 40-ml/min rotameter, to be used for leak-check of
the sampling train.
6.2 Sample Recovery. The following items are required for sample
recovery:
6.2.1 Wash Bottles. Polyethylene or glass, 500-ml, two.
6.2.2 Sample Vials. Glass, 40-ml, with Teflon ®-lined septa, to
store impinger samples (one per sample).
6.2.3 Graduated Cylinder. 100-ml size.
6.3 Analysis. The following are required for analysis:
6.3.1 Gas Chromatograph. GC with an FID, programmable
temperature control, and heated liquid injection port.
6.3.2 Pump. Capable of pumping 100 ml/min. For flushing sample
loop.
6.3.3 Flow Meter. To monitor accurately sample loop flow rate of
100 ml/min.
6.3.4 Regulators. Two-stage regulators used on gas cylinders for
GC and for cylinder standards.
6.3.5 Recorder. To record, integrate, and store
chromatograms.
6.3.6 Syringes. 1.0- and 10-microliter (l) size, calibrated, for
injecting samples.
6.3.7 Tubing Fittings. Stainless steel, to plumb GC and gas
cylinders.
6.3.8 Vials. Two 5.0-ml glass vials with screw caps fitted with
Teflon ®-lined septa for each sample.
6.3.9 Pipettes. Volumetric type, assorted sizes for preparing
calibration standards.
6.3.10 Volumetric Flasks. Assorted sizes for preparing
calibration standards.
6.3.11 Vials. Glass 40-ml with Teflon ®-lined septa, to store
calibration standards (one per standard).
7.0 Reagents and Standards Note:
Unless otherwise indicated, all reagents must conform to the
specifications established by the Committee on Analytical Reagents
of the American Chemical Society. Where such specifications are not
available, use the best available grade.
7.1 Sampling. The following are required for sampling:
7.1.1 Water. Deionized distilled to conform to the American
Society for Testing and Materials (ASTM) Specification D 1193-77,
Type 3. At the option of the analyst, the potassium permanganate
(KMnO4) test for oxidizable organic matter may be omitted when high
concentrations of organic matter are not expected to be
present.
7.1.2 Silica Gel. Deactivated chromatographic grade 20/40 mesh
silica gel packed in glass adsorbent tubes. The silica gel is
packed in two sections. The front section contains 520 milligrams
(mg) of silica gel, and the back section contains 260 mg.
7.2 Analysis. The following are required for analysis:
7.2.1 Water. Same as specified in section 7.1.1.
7.2.2 [Reserved]
7.2.3 Methanol Stock Standard. Prepare a methanol stock standard
by weighing 1 gram of methanol into a 100-ml volumetric flask.
Dilute to 100 ml with water.
7.2.3.1 Methanol Working Standard. Prepare a methanol working
standard by pipetting 1 ml of the methanol stock standard into a
100-ml volumetric flask. Dilute the solution to 100 ml with
water.
7.2.3.2 Methanol Standards For Impinger Samples. Prepare a
series of methanol standards by pipetting 1, 2, 5, 10, and 25 ml of
methanol working standard solution respectively into five 50-ml
volumetric flasks. Dilute the solutions to 50 ml with water. These
standards will have 2, 4, 10, 20, and 50 µg/ml of methanol,
respectively. After preparation, transfer the solutions to 40-ml
glass vials capped with Teflon ® septa and store the vials under
refrigeration. Discard any excess solution.
7.2.3.3 Methanol Standards for Adsorbent Tube Samples. Prepare a
series of methanol standards by first pipetting 10 ml of the
methanol working standard into a 100-ml volumetric flask and
diluting the contents to exactly 100 ml with deionized distilled
water. This standard will contain 10 µg/ml of methanol. Pipette 5,
15, and 25 ml of this standard, respectively, into three 50-ml
volumetric flasks. Dilute each solution to 50 ml with deionized
distilled water. These standards will have 1, 3, and 5 µg/ml of
methanol, respectively. Transfer all four standards into 40-ml
glass vials capped with Teflon®-lined septa and store under
refrigeration. Discard any excess solution.
7.2.4 GC Column. Capillary column, 30 meters (100 feet) long
with an inside diameter (ID) of 0.53 mm (0.02 inch), coated with DB
624 to a film thickness of 3.0 micrometers, (µm) or an equivalent
column. Alternatively, a 30-meter capillary column coated with
polyethylene glycol to a film thickness of 1 µm such as AT-WAX or
its equivalent.
7.2.5 Helium. Ultra high purity.
7.2.6 Hydrogen. Zero grade.
7.2.7 Oxygen. Zero grade.
8.0 Procedure
8.1 Sampling. The following items are required for sampling:
8.1.1 Preparation of Collection Train. Measure 20 ml of water
into the midget impinger. The adsorbent tube must contain 520 mg of
silica gel in the front section and 260 mg of silica gel in the
backup section. Assemble the train as shown in Figure 308-1. An
optional, second impinger that is left empty may be placed in front
of the water-containing impinger to act as a condensate trap. Place
crushed ice and water around the impinger.
8.1.2 Leak Check. A leak check before and after the sampling run
is mandatory. The leak-check procedure is as follows:
Temporarily attach a suitable (e.g., 0- to 40-ml/min)
rotameter to the outlet of the DGM, and place a vacuum gauge at or
near the probe inlet. Plug the probe inlet, pull a vacuum of at
least 250 mm (10 inch) Hg or the highest vacuum experienced during
the sampling run, and note the flow rate as indicated by the
rotameter. A leakage rate in excess of 2 percent of the average
sampling rate is acceptable.
Note:
Carefully release the probe inlet plug before turning off the
pump.
8.1.3 Sample Collection. Record the initial DGM reading and
barometric pressure. To begin sampling, position the tip of the
Teflon ® tubing at the sampling point, connect the tubing to the
impinger, and start the pump. Adjust the sample flow to a constant
rate between 200 and 1000 ml/min as indicated by the rotameter.
Maintain this constant rate (±10 percent) during the entire
sampling run. Take readings (DGM, temperatures at DGM and at
impinger outlet, and rate meter) at least every 5 minutes. Add more
ice during the run to keep the temperature of the gases leaving the
last impinger at 20 °C (68 °F) or less. At the conclusion of each
run, turn off the pump, remove the Teflon ® tubing from the stack,
and record the final readings. Conduct a leak check as in section
8.1.2. (This leak check is mandatory.) If a leak is found, void the
test run or use procedures acceptable to the Administrator to
adjust the sample volume for the leakage.
8.2 Sample Recovery. The following items are required for sample
recovery:
8.2.1 Impinger. Disconnect the impinger. Pour the contents of
the midget impinger into a graduated cylinder. Rinse the midget
impinger and the connecting tubes with water, and add the rinses to
the graduated cylinder. Record the sample volume. Transfer the
sample to a glass vial and cap with a Teflon ® septum. Discard any
excess sample. Place the samples in an ice chest for shipment to
the laboratory.
8.2.2. Adsorbent Tubes. Seal the silica gel adsorbent tubes and
place them in an ice chest for shipment to the laboratory.
9.0 Quality Control
9.1 Miscellaneous Quality Control Measures. The following
quality control measures are required:
Section |
Quality control measure |
Effect |
8.1.2, 8.1.3,
10.1 |
Sampling equipment leak check
and calibration |
Ensures accurate measurement
of sample volume. |
10.2 |
GC calibration |
Ensures precision of GC
analysis. |
13.0 |
Methanol spike recovery
check |
Verifies all methanol in stack
gas is being captured in impinge/adsorbent tube setup. |
10.0 Calibration and Standardization
10.1 Metering System. The following items are required for the
metering system:
10.1.1 Initial Calibration.
10.1.1.1 Before its initial use in the field, first leak-check
the metering system (drying tube, needle valve, pump, rotameter,
and DGM) as follows: Place a vacuum gauge at the inlet to the
drying tube, and pull a vacuum of 250 mm (10 inch) Hg; plug or
pinch off the outlet of the flow meter, and then turn off the pump.
The vacuum shall remain stable for at least 30 seconds. Carefully
release the vacuum gauge before releasing the flow meter end.
10.1.1.2 Next, remove the drying tube, and calibrate the
metering system (at the sampling flow rate specified by the method)
as follows: Connect an appropriately sized wet test meter (e.g., 1
liter per revolution (0.035 cubic feet per revolution)) to the
inlet of the drying tube. Make three independent calibrations runs,
using at least five revolutions of the DGM per run. Calculate the
calibration factor, Y (wet test meter calibration volume divided by
the DGM volume, both volumes adjusted to the same reference
temperature and pressure), for each run, and average the results.
If any Y-value deviates by more than 2 percent from the average,
the metering system is unacceptable for use. Otherwise, use the
average as the calibration factor for subsequent test runs.
10.1.2 Posttest Calibration Check. After each field test series,
conduct a calibration check as in section 10.1.1 above, except for
the following variations: (a) The leak check is not to be
conducted, (b) three, or more revolutions of the DGM may be used,
and (c) only two independent runs need be made. If the calibration
factor does not deviate by more than 5 percent from the initial
calibration factor (determined in section 10.1.1), then the DGM
volumes obtained during the test series are acceptable. If the
calibration factor deviates by more than 5 percent, recalibrate the
metering system as in section 10.1.1, and for the calculations, use
the calibration factor (initial or recalibration) that yields the
lower gas volume for each test run.
10.1.3 Temperature Sensors. Calibrate against mercury-in-glass
thermometers. An alternative mercury-free thermometer may be used
if the thermometer is, at a minimum, equivalent in terms of
performance or suitably effective for the specific temperature
measurement application.
10.1.4 Rotameter. The rotameter need not be calibrated, but
should be cleaned and maintained according to the manufacturer's
instruction.
10.1.5 Barometer. Calibrate against a mercury barometer.
10.2 Gas Chromatograph. The following procedures are required
for the gas chromatograph:
10.2.1 Initial Calibration. Inject 1 µl of each of the standards
prepared in sections 7.2.3.3 and 7.2.3.4 into the GC and record the
response. Repeat the injections for each standard until two
successive injections agree within 5 percent. Using the mean
response for each calibration standard, prepare a linear least
squares equation relating the response to the mass of methanol in
the sample. Perform the calibration before analyzing each set of
samples.
10.2.2 Continuing Calibration. At the beginning of each day,
analyze the mid level calibration standard as described in section
10.5.1. The response from the daily analysis must agree with the
response from the initial calibration within 10 percent. If it does
not, the initial calibration must be repeated.
11.0 Analytical Procedure
11.1 Gas Chromatograph Operating Conditions. The following
operating conditions are required for the GC:
11.1.1 Injector. Configured for capillary column, splitless, 200
°C (392 °F).
11.1.2 Carrier. Helium at 10 ml/min.
11.1.3 Oven. Initially at 45 °C for 3 minutes; then raise by 10
°C to 70 °C; then raise by 70 °C/min to 200 °C.
11.2 Impinger Sample. Inject 1 µl of the stored sample into the
GC. Repeat the injection and average the results. If the sample
response is above that of the highest calibration standard, either
dilute the sample until it is in the measurement range of the
calibration line or prepare additional calibration standards. If
the sample response is below that of the lowest calibration
standard, prepare additional calibration standards. If additional
calibration standards are prepared, there shall be at least two
that bracket the response of the sample. These standards should
produce approximately 50 percent and 150 percent of the response of
the sample.
11.3 Silica Gel Adsorbent Sample. The following items are
required for the silica gel adsorbent samples:
11.3.1 Preparation of Samples. Extract the front and backup
sections of the adsorbent tube separately. With a file, score the
glass adsorbent tube in front of the first section of silica gel.
Break the tube open. Remove and discard the glass wool. Transfer
the first section of the silica gel to a 5-ml glass vial and
stopper the vial. Remove the spacer between the first and second
section of the adsorbent tube and discard it. Transfer the second
section of silica gel to a separate 5-ml glass vial and stopper the
vial.
11.3.2 Desorption of Samples. Add 3 ml of deionized distilled
water to each of the stoppered vials and shake or vibrate the vials
for 30 minutes.
11.3.3 Inject a 1-µl aliquot of the diluted sample from each
vial into the GC. Repeat the injection and average the results. If
the sample response is above that of the highest calibration
standard, either dilute the sample until it is in the measurement
range of the calibration line or prepare additional calibration
standards. If the sample response is below that of the lowest
calibration standard, prepare additional calibration standards. If
additional calibration standards are prepared, there shall be at
least two that bracket the response of the sample. These standards
should produce approximately 50 percent and 150 percent of the
response of the sample.
12.0 Data Analysis and Calculations
12.1 Nomenclature.
Caf = Concentration of methanol in the front of the adsorbent tube,
µg/ml. Cab = Concentration of methanol in the back of the adsorbent
tube, µg/ml. Ci = Concentration of methanol in the impinger portion
of the sample train,µg/ml. E = Mass emission rate of methanol,
µg/hr (lb/hr). ms = Total mass of compound measured in impinger and
on adsorbent with spiked train (mg). mu = Total mass of compound
measured in impinger and on adsorbent with unspiked train (mg). mv
= Mass per volume of spiked compound measured (mg/L). Mtot = Total
mass of methanol collected in the sample train, µg. Pbar =
Barometric pressure at the exit orifice of the DGM, mm Hg (in. Hg).
Pstd = Standard absolute pressure, 760 mm Hg (29.92 in. Hg). Qstd =
Dry volumetric stack gas flow rate corrected to standard
conditions, dscm/hr (dscf/hr). R = fraction of spiked compound
recovered s = theoretical concentration (ppm) of spiked target
compound Tm = Average DGM absolute temperature, degrees K (°R).
Tstd = Standard absolute temperature, 293 degrees K (528 °R). Vaf =
Volume of front half adsorbent sample, ml. Vab = Volume of back
half adsorbent sample, ml. Vi = Volume of impinger sample, ml. Vm =
Dry gas volume as measured by the DGM, dry cubic meters (dcm), dry
cubic feet (dcf). Vm(std) = Dry gas volume measured by the DGM,
corrected to standard conditions, dry standard cubic meters (dscm),
dry standard cubic feet (dscf).
12.2 Mass of Methanol. Calculate the total mass of methanol
collected in the sampling train using Equation 308-1.
12.3 Dry Sample Gas Volume, Corrected to Standard Conditions.
Calculate the volume of gas sampled at standard conditions using
Equation 308-2.
12.4 Mass Emission Rate of Methanol. Calculate the mass emission
rate of methanol using Equation 308-3.
12.5 Recovery Fraction (R)

13.0 Method
Performance
Since a potential sample may contain a variety of compounds from
various sources, a specific precision limit for the analysis of
field samples is impractical. Precision in the range of 5 to 10
percent relative standard deviation (RSD) is typical for gas
chromatographic techniques, but an experienced GC operator with a
reliable instrument can readily achieve 5 percent RSD. For this
method, the following combined GC/operator values are required.
(a) Precision. Calibration standards must meet the requirements
in section 10.2.1 or 10.2.2 as applicable.
(b) Recovery. After developing an appropriate sampling and
analytical system for the pollutants of interest, conduct the
following spike recovery procedure at each sampling point where the
method is being applied.
i. Methanol Spike. Set up two identical sampling trains.
Collocate the two sampling probes in the stack. The probes shall be
placed in the same horizontal plane, where the first probe tip is
2.5 cm from the outside edge of the other. One of the sampling
trains shall be designated the spiked train and the other the
unspiked train. Spike methanol into the impinger, and onto the
adsorbent tube in the spiked train prior to sampling. The total
mass of methanol shall be 40 to 60 percent of the mass expected to
be collected with the unspiked train. Sample the stack gas into the
two trains simultaneously. Analyze the impingers and adsorbents
from the two trains utilizing identical analytical procedures and
instrumentation. Determine the fraction of spiked methanol
recovered (R) by combining the amount recovered in the impinger and
in the adsorbent tube, using the equations in section 12.5.
Recovery values must fall in the range: 0.70 ≤ R ≤ 1.30. Report the
R value in the test report.
ii. [Reserved]
14.0 Pollution Prevention [Reserved] 15.0 Waste Management
[Reserved] 16.0 Bibliography
1. Rom, J.J. “Maintenance, Calibration, and Operation of
Isokinetic Source Sampling Equipment.” Office of Air Programs,
Environmental Protection Agency. Research Triangle Park, NC.
APTD-0576 March 1972.
2. Annual Book of ASTM Standards. Part 31; Water, Atmospheric
Analysis. American Society for Testing and Materials. Philadelphia,
PA. 1974. pp. 40-42.
3. Westlin, P.R. and R.T. Shigehara. “Procedure for Calibrating
and Using Dry Gas Volume Meters as Calibration Standards.” Source
Evaluation Society Newsletter. 3 (1) :17-30. February
1978.
4. Yu, K.K. “Evaluation of Moisture Effect on Dry Gas Meter
Calibration.” Source Evaluation Society Newsletter. 5 (1)
:24-28. February 1980.
5. NIOSH Manual of Analytical Methods, Volume 2. U.S. Department
of Health and Human Services National Institute for Occupational
Safety and Health. Center for Disease Control. 4676 Columbia
Parkway, Cincinnati, OH 45226. (available from the Superintendent
of Documents, Government Printing Office, Washington, DC
20402.)
6. Pinkerton, J.E. “Method for Measuring Methanol in Pulp Mill
Vent Gases.” National Council of the Pulp and Paper Industry for
Air and Stream Improvement, Inc., New York, NY.
17.0 Tables, Diagrams, Flowcharts, and Validation Data [Reserved]
Method 310A - Determination of Residual Hexane Through Gas
Chromatography 1.0 Scope and Application
1.1 This method is used to analyze any crumb rubber or water
samples for residual hexane content.
1.2 The sample is heated in a sealed bottle with an internal
standard and the vapor is analyzed by gas chromatography.
2.0 Summary of Method
2.1 This method, utilizing a capillary column gas chromatograph
with a flame ionization detector, determines the concentration of
residual hexane in rubber crumb samples.
3.0 Definitions
3.1 The definitions are included in the text as needed.
4.0 Interferences
4.1 There are no known interferences.
5.0 Safety
5.1 It is the responsibility of the user of this procedure to
establish safety and health practices applicable to their specific
operation.
6.0 Equipment and Supplies
6.1 Gas Chromatograph with a flame ionization detector and data
handling station equipped with a capillary column 30 meters
long.
6.2 Chromatograph conditions for Sigma 1:
6.2.1 Helium pressure: 50# inlet A, 14# aux
6.2.2 Carrier flow: 25 cc/min
6.2.3 Range switch: 100x
6.2.4 DB: 1 capillary column
6.3 Chromatograph conditions for Hewlett-Packard GC:
6.3.1 Initial temperature: 40 °C
6.3.2 Initial time: 8 min
6.3.3 Rate: 0
6.3.4 Range: 2
6.3.5 DB: 1705 capillary column
6.4 Septum bottles and stoppers
6.5 Gas Syringe - 0.5 cc
7.0 Reagents and Standards
7.1 Chloroform, 99.9 + %, A.S.C. HPLC grade
8.0 Sample Collection, Preservation, and Storage
8.1 A representative sample should be caught in a clean 8 oz.
container with a secure lid.
8.2 The container should be labeled with sample identification,
date and time.
9.0 Quality Control
9.1 The instrument is calibrated by injecting calibration
solution (Section 10.2 of this method) five times.
9.2 The retention time for components of interest and relative
response of monomer to the internal standard is determined.
9.3 Recovery efficiency must be determined once for each sample
type and whenever modifications are made to the method.
9.3.1 Determine the percent hexane in three separate dried
rubber crumb samples.
9.3.2 Weigh a portion of each crumb sample into separate sample
bottles and add a known amount of hexane (10 microliters) by
microliter syringe and 20 microliters of internal standard. Analyze
each by the described procedure and calculate the percent recovery
of the known added hexane.
9.3.3 Repeat the previous step using twice the hexane level (20
microliters), analyze and calculate the percent recovery of the
known added hexane.
9.3.4 Set up two additional sets of samples using 10 microliters
and 20 microliters of hexane as before, but add an amount of water
equal to the dry crumb used. Analyze and calculate percent recovery
to show the effect of free water on the results obtained.
9.3.5 A value of R between 0.70 and 1.30 is acceptable.
9.3.6 R shall be used to correct all reported results for each
compound by dividing the measured results of each compound by the R
for that compound for the same sample type.
10.0 Calibration and Instrument Settings
10.1 Calibrate the chromatograph using a standard made by
injecting 10 µl of fresh hexane and 20 µl of chloroform into a
sealed septum bottle. This standard will be 0.6 wt.% total
hexane based on 1 gram of dry rubber.
10.2 Analyze the hexane used and calculate the percentage of
each hexane isomer (2-methylpentane, 3-methylpentane, n-hexane, and
methylcyclo-pentane). Enter these percentages into the method
calibration table.
10.3 Heat the standard bottle for 30 minutes in a 105 °C
oven.
10.4 Inject about 0.25 cc of vapor into the gas chromatograph
and after the analysis is finished, calibrate according to the
procedures described by the instrument manufacturer.
11.0 Procedure
11.1 Using a cold mill set at a wide roller gap (125-150 mm),
mill about 250 grams of crumb two times to homogenize the
sample.
11.2 Weigh about 2 grams of wet crumb into a septum bottle and
cap with a septum ring. Add 20 µl of chloroform with a syringe and
place in a 105 °C oven for 45 minutes.
11.3 Run the moisture content on a separate portion of the
sample and calculate the grams of dry rubber put into the septum
bottle.
11.4 Set up the data station on the required method and enter
the dry rubber weight in the sample weight field.
11.5 Inject a 0.25 cc vapor sample into the chromatograph and
push the start button.
11.6 At the end of the analysis, the data station will print a
report listing the concentration of each identified component.
11.7 To analyze water samples, pipet 5 ml of sample into the
septum bottle, cap and add 20 µl of chloroform. Place in a 105 °C
oven for 30 minutes.
11.8 Enter 5 grams into the sample weight field.
11.9 Inject a 0.25 cc vapor sample into the chromatograph and
push the start button.
11.10 At the end of the analysis, the data station will print a
report listing the concentration of each identified component.
12.0 Data Analysis and Calculation
12.1 For samples that are prepared as in section 11 of this
method, ppm n-hexane is read directly from the computer.
12.2 The formulas for calculation of the results are as
follows:
ppmhexane = (Ahexane × Rhexane)/(Ais × Ris) Where: Ahexane = area
of hexane Rhexane = response of hexane Ais = area of the internal
standard Ris = response of the internal standard % hexane in crumb
= (ppmhexane/sample amount)100
12.3 Correct the results by the value of R (as determined in
sections 9.3.4, 9.3.5, and 9.3.6 of this method).
13.0 Method Performance
13.1 The test has a standard deviation of 0.14 wt% at 0.66 wt%
hexane. Spike recovery of 12 samples at two levels of hexane
averaged 102.3%. Note: Recovery must be determined for each type of
sample. The values given here are meant to be examples of method
performance.
14.0 Pollution Prevention
14.1 Waste generation should be minimized where possible. Sample
size should be an amount necessary to adequately run the
analysis.
15.0 Waste Management
15.1 All waste shall be handled in accordance with federal and
state environmental regulations.
16.0 References and Publications
16.1 DSM Copolymer Test Method T-3380.
Method 310B - Determination of Residual Hexane Through Gas
Chromatography 1.0 Scope and Application
Analyte |
CAS No. |
Matrix |
Method sensitivity (5.5g
sample size) |
Hexane |
110-54-3 |
Rubber crumb |
.01 wt%. |
Applicable
Termonomer |
|
Rubber crumb |
.001 wt%. |
1.1 Data Quality Objectives:
In the production of ethylene-propylene terpolymer crumb rubber,
the polymer is recovered from solution by flashing off the solvent
with steam and hot water. The resulting water-crumb slurry is then
pumped to the finishing units. Certain amounts of solvent (hexane
being the most commonly used solvent) and diene monomer remain in
the crumb. The analyst uses the following procedure to determine
those amounts.
2.0 Summary of Method
2.1 The crumb rubber sample is dissolved in toluene to which
heptane has been added as an internal standard. Acetone is then
added to this solution to precipitate the crumb, and the
supernatant is analyzed for hexane and diene by a gas chromatograph
equipped with a flame ionization detector (FID).
3.0 Definitions
3.1 Included in text as needed.
4.0 Interferences
4.1 None known.
4.2 Benzene, introduced as a contaminant in the toluene solvent,
elutes between methyl cyclopentane and cyclohexane. However, the
benzene peak is completely resolved.
4.3 2,2-dimethyl pentane, a minor component of the hexane used
in our process, elutes just prior to methyl cyclopentane. It is
included as “hexane” in the analysis whether it is integrated
separately or included in the methyl cyclopentane peak.
5.0 Safety
5.1 This procedure does not purport to address all of the safety
concerns associated with its use. It is the responsibility of the
user of this procedure to establish appropriate safety and health
practices and determine the applicability of regulatory limitations
prior to use.
5.2 Chemicals used in this analysis are flammable and hazardous
(see specific toxicity information below). Avoid contact with
sources of ignition during sample prep. All handling should be done
beneath a hood. Playtex or nitrile gloves recommended.
5.3 Hexane is toxic by ingestion and inhalation. Vapor
inhalation causes irritation of nasal and respiratory passages,
headache, dizziness, nausea, central nervous system depression.
Chronic overexposure can cause severe nerve damage. May cause
irritation on contact with skin or eyes. May cause damage to
kidneys.
5.4 Termonomer may be harmful by inhalation, ingestion, or skin
absorption. Vapor or mist is irritating to the eyes, mucous
membranes, and upper respiratory tract. Causes skin irritation.
5.5 Toluene is harmful or fatal if swallowed. Vapor harmful if
inhaled. Symptoms: headache, dizziness, hallucinations, distorted
perceptions, changes in motor activity, nausea, diarrhea,
respiratory irritation, central nervous system depression,
unconsciousness, liver, kidney and lung damage. Contact can cause
severe eye irritation. May cause skin irritation. Causes irritation
of eyes, nose, and throat.
5.6 Acetone, at high concentrations or prolonged overexposure,
may cause headache, dizziness, irritation of eyes and respiratory
tract, loss of strength, and narcosis. Eye contact causes severe
irritation; skin contact may cause mild irritation. Concentrations
of 20,000 ppm are immediately dangerous to life and health.
5.7 Heptane is harmful if inhaled or swallowed. May be harmful
if absorbed through the skin. Vapor or mist is irritating to the
eyes, mucous membranes, and upper respiratory tract. Prolonged or
repeated exposure to skin causes defatting and dermatitis.
5.8 The steam oven used to dry the polymer in this procedure is
set at 110 °C. Wear leather gloves when removing bottles from the
oven.
6.0 Equipment and Supplies
6.1 4000-ml volumetric flask
6.2 100-ml volumetric pipette
6.3 1000-ml volumetric flask
6.4 8-oz. French Square sample bottles with plastic-lined
caps
6.5 Top-loading balance
6.6 Laboratory shaker
6.7 Laboratory oven set at 110 °C (steam oven)
6.8 Gas chromatograph, Hewlett-Packard 5890A, or equivalent,
interfaced with HP 7673A (or equivalent) autosampler (equipped with
nanoliter adapter and robotic arm), and HP 3396 series II or 3392A
(or equivalent) integrator/controller.
6.9 GC column, capillary type, 50m × 0.53mm, methyl silicone, 5
micron film thickness, Quadrex, or equivalent.
6.10 Computerized data acquisition system, such as CIS/CALS
6.11 Crimp-top sample vials and HP p/n 5181-1211 crimp caps, or
screw-top autosampler vials and screw tops.
6.12 Glass syringes, 5-ml, with “Luer-lock” fitting
6.13 Filters, PTFE, .45 µm pore size, Gelman Acrodisc or
equivalent, to fit on Luer-lock syringes (in 6.12, above).
7.0 Reagents and Standards
7.1 Reagent toluene, EM Science Omnisolv (or equivalent)
Purity Check: Prior to using any bottle of reagent toluene,
analyze it according to section 11.2 of this method. Use the bottle
only if hexane, heptane, and termonomer peak areas are less than 15
each (note that an area of 15 is equivalent to less than 0.01 wt%
in a 10g sample).
7.2 Reagent acetone, EM Science Omnisolv HR-GC (or
equivalent)
Purity Check: Prior to using any bottle of reagent
acetone, analyze it according to section 11.2 of this method. Use
the bottle only if hexane, heptane, and termonomer peak areas are
less than 15 each.
7.3 Reagent heptane, Aldrich Chemical Gold Label, Cat #15,487-3
(or equivalent)
Purity Check: Prior to using any bottle of reagent
heptane, analyze it according to section 11.2 of this method. Use
the bottle only if hexane and termonomer peak areas are less than 5
each.
7.4 Internal standard solution - used as a concentrate for
preparation of the more dilute Polymer Dissolving Solution. It
contains 12.00g heptane/100ml of solution which is 120.0g per
liter.
Preparation of internal standard solution (polymer dissolving
stock solution):
Action |
Notes |
7.4.1 Tare a
clean, dry 1-liter volumetric flask on the balance. Record the
weight to three places |
If the 1-liter volumetric
flask is too tall to fit in the balance case, you can shield the
flask from drafts by inverting a paint bucket with a hole cut in
the bottom over the balance cover. Allow the neck of the flask to
project through the hole in the bucket. |
7.4.2 Weigh 120.00
g of n-heptane into the flask. Record the total weight of the flask
and heptane as well as the weight of heptane added |
Use 99 + % n-heptane from
Aldrich or Janssen Chimica. |
7.4.3 Fill the
flask close to the mark with toluene, about 1 to 2″ below the
mark |
Use EM Science Omnisolve
toluene, Grade TX0737-1, or equivalent. |
7.4.4 Shake the
flask vigorously to mix the contents |
Allow any bubbles to clear
before proceeding to the next step. |
7.4.5 Top off the
flask to the mark with toluene. Shake vigorously, as in section
7.4.4 of this method, to mix well |
|
7.4.6 Weigh the
flask containing the solution on the three place balance record the
weight |
|
7.4.7 Transfer the
contents of the flask to a 1 qt Boston round bottle |
Discard any excess
solution |
7.4.8 Label the
bottle with the identity of the contents, the weights of heptane
and toluene used, the date of preparation and the preparer's
name |
Be sure to include the words
“Hexane in Crumb Polymer Dissolving Stock Solution” on the
label. |
7.4.9 Refrigerate
the completed blend for the use of the routine Technicians |
|
7.5 Polymer Dissolving Solution (“PDS”) - Heptane (as internal
standard) in toluene. This solution contains 0.3g of heptane
internal standard per 100 ml of solution.
7.5.1 Preparation of Polymer Dissolving Solution. Fill a
4,000-ml volumetric flask about 3/4 full with toluene.
7.5.2 Add 100 ml of the internal standard solution (section 7.4
of this method) to the flask using the 100ml pipette.
7.5.3 Fill the flask to the mark with toluene. Discard any
excess.
7.5.4 Add a large magnetic stirring bar to the flask and mix by
stirring.
7.5.5 Transfer the polymer solvent solution to the one-gallon
labeled container with 50ml volumetric dispenser attached.
7.5.6 Purity Check: Analyze according to section 11.2.
NOTE: You must “precipitate” the sample with an equal part
of acetone (thus duplicating actual test conditions - see section
11.1 of this method, sample prep) before analyzing. Analyze the
reagent 3 times to quantify the C6 and termonomer interferences.
Inspect the results to ensure good agreement among the three runs
(within 10%).
7.5.7 Tag the bottle with the following information:
POLYMER DISSOLVING SOLUTION FOR C6 IN CRUMB ANALYSIS PREPARER'S
NAME DATE CALS FILE ID'S OF THE THREE ANALYSES FOR PURITY (from
section 7.5.6 of this method)
7.6 Quality Control Solution: the quality control solution is
prepared by adding specific amounts of mixed hexanes (barge
hexane), n-nonane and termonomer to some polymer dissolving
solution. Nonane elutes in the same approximate time region as
termonomer and is used to quantify in that region because it has a
longer shelf life. Termonomer, having a high tendency to
polymerize, is used in the QC solution only to ensure that both
termonomer isomers elute at the proper time.
First, a concentrated stock solution is prepared; the final QC
solution can then be prepared by diluting the stock solution.
7.6.1 In preparation of stock solution, fill a 1-liter
volumetric flask partially with polymer dissolving solution (PDS) -
see section 7.5 of this method. Add 20.0 ml barge hexane, 5.0 ml
n-nonane, and 3 ml termonomer. Finish filling the volumetric to the
mark with PDS.
7.6.2 In preparation of quality control solution, dilute the
quality control stock solution (above) precisely 1:10 with PDS,
i.e. 10 ml of stock solution made up to 100 ml (volumetric flask)
with PDS. Pour the solution into a 4 oz. Boston round bottle and
store in the refrigerator.
8.0 Sample Collection, Preservation and Storage
8.1 Line up facility to catch crumb samples. The facility is a
special facility where the sample is drawn.
8.1.1 Ensure that the cock valve beneath facility is closed.
8.1.2 Line up the system from the slurry line cock valve to the
cock valve at the nozzle on the stripper.
8.1.3 Allow the system to flush through facility for a period of
30 seconds.
8.2 Catch a slurry crumb sample.
8.2.1 Simultaneously close the cock valves upstream and
downstream of facility.
8.2.2 Close the cock valve beneath the slurry line in
service.
8.2.3 Line up the cooling tower water through the sample bomb
water jacket to the sewer for a minimum of 30 minutes.
8.2.4 Place the sample catching basket beneath facility and open
the cock valve underneath the bomb to retrieve the rubber
crumb.
8.2.5 If no rubber falls by gravity into the basket, line up
nitrogen to the bleeder upstream of the sample bomb and force the
rubber into the basket.
8.2.6 Close the cock valve underneath the sample bomb.
8.3 Fill a plastic “Whirl-pak” sample bag with slurry crumb and
send it to the lab immediately.
8.4 Once the sample reaches the lab, it should be prepped as
soon as possible to avoid hexane loss through evaporation. Samples
which have lain untouched for more than 30 minutes should be
discarded.
9.0 Quality Control
Quality control is monitored via a computer program that tracks
analyses of a prepared QC sample (from section 7.6.2 of this
method). The QC sample result is entered daily into the program,
which plots the result as a data point on a statistical chart. If
the data point does not satisfy the “in-control” criteria (as
defined by the lab quality facilitator), an “out-of-control” flag
appears, mandating corrective action.
In addition, the area of the n-heptane peak is monitored so that
any errors in making up the polymer dissolving solution will be
caught and corrected. Refer to section 12.4 of this method.
9.1 Fill an autosampler vial with the quality control solution
(from section 7.6.2 of this method) and analyze on the GC as normal
(per section 11 of this method).
9.2 Add the concentrations of the 5 hexane isomers as they
appear on the CALS printout. Also include the 2,2-dimethyl-pentane
peak just ahead of the methyl cyclopentane (the fourth major
isomer) peak in the event that the peak integration split this peak
out. Do not include the benzene peak in the sum. Note the nonane
concentration. Record both results (total hexane and nonane) in the
QC computer program. If out of control, and GC appears to be
functioning within normal parameters, reanalyze a fresh control
sample. If the fresh QC is not in control, check stock solution for
contaminants or make up a new QC sample with the toluene currently
in use. If instrument remains out-of-control, more thorough GC
troubleshooting may be needed.
Also, verify that the instrument has detected both isomers of
termonomer (quantification not necessary - see section 7.0 of this
method).
9.3 Recovery efficiency must be determined for high ethylene
concentration, low ethylene concentration, E-P terpolymer, or oil
extended samples and whenever modifications are made to the method.
Recovery shall be between 70 and 130 percent. All test results must
be corrected by the recovery efficiency value (R).
9.3.1 Approximately 10 grams of wet EPDM crumb (equivalent to
about 5 grams of dry rubber) shall be added to six sample bottles
containing 100 ml of hexane in crumb polymer dissolving solution
(toluene containing 0.3 gram n-heptane/100 ml solution). The
polymer shall be dissolved by agitating the bottles on a shaker for
4 hours. The polymer shall be precipitated using 100 ml
acetone.
9.3.2 The supernatant liquid shall be decanted from the polymer.
Care shall be taken to remove as much of the liquid phase from the
sample as possible to minimize the effect of retained liquid phase
upon the next cycle of the analysis. The supernatant liquid shall
be analyzed by gas chromatography using an internal standard
quantitation method with heptane as the internal standard.
9.3.3 The precipitated polymer from the steps described above
shall be redissolved using toluene as the solvent. No heptane shall
be added to the sample in the second dissolving step. The toluene
solvent and acetone precipitant shall be determined to be free of
interfering compounds.
9.3.4 The rubber which was dissolved in the toluene shall be
precipitated with acetone as before, and the supernatant liquid
decanted from the precipitated polymer. The liquid shall be
analyzed by gas chromatography and the rubber phase dried in a
steam-oven to determine the final polymer weight.
9.3.5 The ratios of the areas of the hexane peaks and of the
heptane internal standard peak shall be calculated for each of the
six samples in the two analysis cycles outlined above. The area
ratios of the total hexane to heptane (R1) shall be determined for
the two analysis cycles of the sample set. The ratio of the values
of R1 from the second analysis cycle to the first cycle shall be
determined to give a second ratio (R2).
10.0 Calibration and Standardization
The procedure for preparing a Quality Control sample with the
internal standard in it is outlined in section 7.6 of this
method.
10.1 The relative FID response factors for n-heptane, the
internal standard, versus the various hexane isomers and termonomer
are relatively constant and should seldom need to be altered.
However Baseline construction is a most critical factor in the
production of good data. For this reason, close attention should be
paid to peak integration. Procedures for handling peak integration
will depend upon the data system used.
10.2 If recalibration of the analysis is needed, make up a
calibration blend of the internal standard and the analytes as
detailed below and analyze it using the analytical method used for
the samples.
10.2.1 Weigh 5 g heptane into a tared scintillation vial to five
places.
10.2.2 Add 0.2 ml termonomer to the vial and reweigh.
10.2.3 Add 0.5 ml hexane to the vial and reweigh.
10.2.4 Cap, and shake vigorously to mix.
10.2.5 Calculate the weights of termonomer and of hexane added
and divide their weights by the weight of the n-heptane added. The
result is the known of given value for the calibration.
10.2.6 Add 0.4 ml of this mixture to a mixture of 100 ml toluene
and 100 ml of acetone. Cap and shake vigorously to mix.
10.2.7 Analyze the sample.
10.2.8 Divide the termonomer area and the total areas of the
hexane peaks by the n-heptane area. This result is the “found”
value for the calibration.
10.2.9 Divide the appropriate “known” value from 10.2.5 by the
found value from 10.2.8. The result is the response factor for the
analyte in question. Previous work has shown that the standard
deviation of the calibration method is about 1% relative.
11.0 Procedure
11.1 SAMPLE PREPARATION
11.1.1 Tare an 8oz sample bottle - Tag attached, cap off; record
weight and sample ID on tag in pencil.
11.1.2 Place crumb sample in bottle: RLA-3: 10 g (gives a dry
wt. of ∼5.5 g).
11.1.3 Dispense 100ml of PDS into each bottle. SAMPLE SHOULD BE
PLACED INTO SOLUTION ASAP TO AVOID HEXANE LOSS - Using
“Dispensette” pipettor. Before dispensing, “purge” the
dispensette (25% of its volume) into a waste bottle to eliminate
any voids.
11.1.4 Tightly cap bottles and load samples into shaker.
11.1.5 Insure that “ON-OFF” switch on the shaker itself is
“ON.”
11.1.6 Locate shaker timer. Insure that toggle switch atop timer
control box is in the middle (“off”) position. If display reads
“04:00” (4 hours), move toggle switch to the left position. Shaker
should begin operating.
11.1.7 After shaker stops, add 100 ml acetone to each sample to
precipitate polymer. Shake minimum of 5 minutes on shaker -
Vistalon sample may not have fully dissolved; nevertheless, for
purposes of consistency, 4 hours is the agreed-upon dissolving
time.
11.1.8 Using a 5-ml glass Luer-lock syringe and Acrodisc filter,
filter some of the supernatant liquid into an autosampler vial;
crimp the vial and load it into the GC autosampler for analysis
(section 11.2 of this method) - The samples are filtered to prevent
polymer buildup in the GC. Clean the syringes in toluene.
11.1.9 Decant remaining supernatant into a hydrocarbon waste
sink, being careful not to discard any of the polymer. Place bottle
of precipitate into the steam oven and dry for six hours - Some
grades of Vistalon produce very small particles in the precipitate,
thus making complete decanting impossible without discarding some
polymer. In this case, decant as much as possible and put into the
oven as is, allowing the oven to drive off remaining supernatant
(this practice is avoided for environmental reasons). WARNING: OVEN
IS HOT - 110 °C (230 °F).
11.1.10 Cool, weigh and record final weight of bottle.
11.2 GC ANALYSIS
11.2.1 Initiate the CALS computer channel.
11.2.2 Enter the correct instrument method into the GC's
integrator.
11.2.3 Load sample vial(s) into autosampler.
11.2.4 Start the integrator.
11.2.5 When analysis is complete, plot CALS run to check
baseline skim.
12.0 Data Analysis and Calculations
12.1 Add the concentrations of the hexane peaks as they appear
on the CALS printout. Do not include the benzene peak in the
sum.
12.2 Subtract any hexane interferences found in the PDS (see
section 7.5.6 of this method); record the result.
12.3 Note the termonomer concentration on the CALS printout.
Subtract any termonomer interference found in the PDS and record
this result in a “% termonomer by GC” column in a logbook.
12.4 Record the area (from CALS printout) of the heptane
internal standard peak in a “C7 area” column in the logbook. This
helps track instrument performance over the long term.
12.5 After obtaining the final dry weight of polymer used
(Section 11.1.10 of this method), record that result in a “dry wt.”
column of the logbook (for oil extended polymer, the amount of oil
extracted is added to the dry rubber weight).
12.6 Divide the %C6 by the dry weight to obtain the total PHR
hexane in crumb. Similarly, divide the % termonomer by the dry
weight to obtain the total PHR termonomer in crumb. Note that PHR
is an abbreviation for “parts per hundred”. Record both the hexane
and termonomer results in the logbook.
12.7 Correct all results by the recovery efficiency value
(R).
13.0 Method Performance
13.1 The method has been shown to provide 100% recovery of the
hexane analyte. The method was found to give a 6% relative standard
deviation when the same six portions of the same sample were
carried through the procedure. Note: These values are examples;
each sample type, as specified in Section 9.3, must be tested for
sample recovery.
14.0 Pollution Prevention
14.1 Dispose of all hydrocarbon liquids in the appropriate
disposal sink system; never pour hydrocarbons down a water
sink.
14.2 As discussed in section 11.1.9 of this method, the analyst
can minimize venting hydrocarbon vapor to the atmosphere by
decanting as much hydrocarbon liquid as possible before oven
drying.
15.0 Waste Management
15.1 The Technician conducting the analysis should follow the
proper waste management practices for their laboratory
location.
16.0 References
16.1 Baton Rouge Chemical Plant Analytical Procedure no. BRCP
1302
16.2 Material Safety Data Sheets (from chemical vendors) for
hexane, ENB, toluene, acetone, and heptane
Method 310C - Determination of Residual N-Hexane in EPDM Rubber
Through Gas Chromatography 1.0 Scope and Application
1.1 This method describes a procedure for the determination of
residual hexane in EPDM wet crumb rubber in the 0.01 - 2% range by
solvent extraction of the hexane followed by gas chromatographic
analysis where the hexane is detected by flame ionization and
quantified via an internal standard.
1.2 This method may involve hazardous materials operations and
equipment. This method does not purport to address all the safety
problems associated with it use, if any. It is the responsibility
of the user to consult and establish appropriate safety and health
practices and determine the applicability of regulatory limitations
prior to use.
2.0 Summary
2.1 Residual hexane contained in wet pieces of EPDM polymer is
extracted with MIBK. A known amount of an internal standard (IS) is
added to the extract which is subsequently analyzed via gas
chromatography where the hexane and IS are separated and detected
utilizing a megabore column and flame ionization detection (FID).
From the response to the hexane and the IS, the amount of hexane in
the EPDM polymer is calculated.
3.0 Definitions
3.1 Hexane - refers to n-hexane
3.2 Heptane - refers to n-heptane
3.3 MIBK - methyl isobutyl ketone (4 methyl 2 - Pentanone)
4.0 Interferences
4.1 Material eluting at or near the hexane and/or the IS will
cause erroneous results. Prior to extraction, solvent blanks must
be analyzed to confirm the absence of interfering peaks.
5.0 Safety
5.1 Review Material Safety Data Sheets of the chemicals used in
this method.
6.0 Equipment and Supplies
6.1 4 oz round glass jar with a wide mouth screw cap lid.
6.2 Vacuum oven.
6.3 50 ml pipettes.
6.4 A gas chromatograph with an auto sampler and a 50 meter,
0.53 ID, methyl silicone column with 5 micron phase thickness.
6.5 Shaker, large enough to hold 10, 4 oz. jars.
6.6 1000 and 4000 ml volumetric flasks.
6.7 Electronic integrator or equivalent data system.
6.8 GC autosampler vials.
6.9 50 uL syringe.
7.0 Reagents and Standards
7.1 Reagent grade Methyl-Iso-Butyl-Ketone (MIBK)
7.2 n-heptane, 99% + purity
7.3 n-hexane, 99% + purity
8.0 Sample Collection
8.1 Trap a sample of the EPDM crumb slurry in the sampling
apparatus. Allow the crumb slurry to circulate through the sampling
apparatus for 5 minutes; then close off the values at the bottom
and top of the sampling apparatus, trapping the crumb slurry. Run
cooling water through the water jacket for a minimum of 30 minutes.
Expel the cooled crumb slurry into a sample catching basket. If the
crumb does not fall by gravity, force it out with demineralized
water or nitrogen. Send the crumb slurry to the lab for
analysis.
9.0 Quality Control
9.1 The Royalene crumb sample is extracted three times with MIBK
containing an internal standard. The hexane from each extraction is
added together to obtain a total hexane content. The percent hexane
in the first extraction is then calculated and used as the recovery
factor for the analysis.
9.2 Follow this test method through section 11.4 of the method.
After removing the sample of the first extraction to be run on the
gas chromatograph, drain off the remainder of the extraction
solvent, retaining the crumb sample in the sample jar. Rinse the
crumb with demineralized water to remove any MIBK left on the
surface of the crumb. Repeat the extraction procedure with fresh
MIBK with internal standard two more times.
9.3 After the third extraction, proceed to section 11.5 of this
method and obtain the percent hexane in each extraction. Use the
sample weight obtained in section 12.1 of this method to calculate
the percent hexane in each of the extracts.
9.4 Add the percent hexane obtained from the three extractions
for a total percent hexane in the sample.
9.5 Use the following equations to determine the recovery factor
(R):
% Recovery of the first extraction = (% hexane in the first
extract/total % hexane) × 100
Recovery Factor (R) = (% Hexane Recovered in the first
extract)/100
10.0 Calibration
10.1 Preparation of Internal Standard (IS) solution:
Accuracy weigh 30 grams of n-heptane into a 1000 ml volumetric
flask. Dilute to the mark with reagent grade MIBK. Label this
Solution “A”. Pipette 100 mls. of Solution A into a 4 liter
volumetric flask. Fill the flask to the mark with reagent MIBK.
Label this Solution “B”. Solution “B” will have a concentration of
0.75 mg/ml of heptane.
10.2 Preparation of Hexane Standard Solution (HS):
Using a 50 uL syringe, weigh by difference, 20 mg of n-hexane
into a 50 ml volumetric flask containing approximately 40 ml of
Solution B. Fill the flask to the mark with Solution B and mix
well.
10.3 Conditions for GC analysis of standards and samples:
Temperature:
Initial = 40 °C
Final = 150 °C
Injector = 160 °C
Detector = 280 °C
Program Rate = 5.0 °C/min
Initial Time = 5 minutes Final Time = 6 minutes
Flow Rate = 5.0 ml/min
Sensitivity = detector response must be adjusted to keep the
hexane and IS on scale.
10.4 Fill an autosampler vial with the HS, analyze it three
times and calculate a Hexane Relative Response Factor (RF) as
follows:
RF = (AIS × CHS × PHS)/(AHS × CIS × PIS) (1) Where: AIS = Area of
IS peak (Heptane) AHS = Area of peak (Hexane Standard) CHS = Mg of
Hexane/50 ml HS CIS = Mg of Heptane/50 ml IS Solution B PIS =
Purity of the IS n-heptane PHS = Purity of the HS n-hexane 11.0
Procedure
11.1 Weight 10 grams of wet crumb into a tared (W1), wide mouth
4 oz. jar.
11.2 Pipette 50 ml of Solution B into the jar with the wet crumb
rubber.
11.3 Screw the cap on tightly and place it on a shaker for 4
hours.
11.4 Remove the sample from the shaker and fill an autosampler
vial with the MIBK extract.
11.5 Analyze the sample two times.
11.6 Analyze the HS twice, followed by the samples. Inject the
HS twice at the end of each 10 samples or at the end of the
run.
12.0 Calculations
12.1 Drain off the remainder of the MIBK extract from the
polymer in the 4 oz. jar. Retain all the polymer in the jar. Place
the uncovered jar and polymer in a heated vacuum oven until the
polymer is dry. Reweigh the jar and polymer (W2) and calculate the
dried sample weight of the polymer as follows:
Dried SW = W2 - W1 (2)
12.2 Should the polymer be oil extended, pipette 10 ml of the
MIBK extract into a tared evaporating dish (W1) and evaporate to
dryness on a steam plate.
Reweigh the evaporating dish containing the extracted oil (W2).
Calculate the oil content of the polymer as follows:
Gram of oil extracted = 5 (W2 - W1) (3)
% Hexane in polymer = (As × RF × CIS × PIS)/(AIS × SW) (4) Where:
As = Area of sample hexane sample peak. AIS = Area of IS peak in
sample. CIS = Concentration of IS in 50 ml. PIS = Purity of IS. SW
= Weight of dried rubber after extraction. (For oil extended
polymer, the amount of oil extracted is added to the dry rubber
weight). % Corrected Hexane = (% Hexane in Polymer)/R (5) R =
Recovery factor determined in section 9 of this method. 13.0 Method
Performance
13.1 Performance must be determined for each sample type by
following the procedures in section 9 of this method.
14.0 Waste Generation
14.1 Waste generation should be minimized where possible.
15.0 Waste Management
15.1 All waste shall be handled in accordance with Federal and
State environmental regulations.
16.0 References [Reserved] Method 311 - Analysis of Hazardous Air
Pollutant Compounds in Paints and Coatings by Direct Injection Into
a Gas Chromatograph 1. Scope and Application
1.1 Applicability. This method is applicable for determination
of most compounds designated by the U.S. Environmental Protection
Agency as volatile hazardous air pollutants (HAP's) (See Reference
1) that are contained in paints and coatings. Styrene, ethyl
acrylate, and methyl methacrylate can be measured by ASTM D
4827-03. Formaldehyde can be measured by ASTM D 5910-05 or ASTM D
1979-91. Toluene diisocyanate can be measured in urethane
prepolymers by ASTM D 3432-89. Method 311 applies only to those
volatile HAP's which are added to the coating when it is
manufactured, not to those that may form as the coating cures
(reaction products or cure volatiles). A separate or modified test
procedure must be used to measure these reaction products or cure
volatiles in order to determine the total volatile HAP emissions
from a coating. Cure volatiles are a significant component of the
total HAP content of some coatings. The term “coating” used in this
method shall be understood to mean paints and coatings.
1.2 Principle. The method uses the principle of gas
chromatographic separation and quantification using a detector that
responds to concentration differences. Because there are many
potential analytical systems or sets of operating conditions that
may represent useable methods for determining the concentrations of
the compounds cited in Section 1.1 in the applicable matrices, all
systems that employ this principle, but differ only in details of
equipment and operation, may be used as alternative methods,
provided that the prescribed quality control, calibration, and
method performance requirements are met. Certified product data
sheets (CPDS) may also include information relevant to the analysis
of the coating sample including, but not limited to, separation
column, oven temperature, carrier gas, injection port temperature,
extraction solvent, and internal standard.
2. Summary of Method
Whole coating is added to dimethylformamide and a suitable
internal standard compound is added. An aliquot of the sample
mixture is injected onto a chromatographic column containing a
stationary phase that separates the analytes from each other and
from other volatile compounds contained in the sample. The
concentrations of the analytes are determined by comparing the
detector responses for the sample to the responses obtained using
known concentrations of the analytes.
3. Definitions [Reserved] 4. Interferences
4.1 Coating samples of unknown composition may contain the
compound used as the internal standard. Whether or not this is the
case may be determined by following the procedures of Section 11
and deleting the addition of the internal standard specified in
Section 11.5.3. If necessary, a different internal standard may be
used.
4.2 The GC column and operating conditions developed for one
coating formulation may not ensure adequate resolution of target
analytes for other coating formulations. Some formulations may
contain nontarget analytes that coelute with target analytes. If
there is any doubt about the identification or resolution of any
gas chromatograph (GC) peak, it may be necessary to analyze the
sample using a different GC column or different GC operating
conditions.
4.3 Cross-contamination may occur whenever high-level and
low-level samples are analyzed sequentially. The order of sample
analyses specified in Section 11.7 is designed to minimize this
problem.
4.4 Cross-contamination may also occur if the devices used to
transfer coating during the sample preparation process or for
injecting the sample into the GC are not adequately cleaned between
uses. All such devices should be cleaned with acetone or other
suitable solvent and checked for plugs or cracks before and after
each use.
5. Safety
5.1 Many solvents used in coatings are hazardous. Precautions
should be taken to avoid unnecessary inhalation and skin or eye
contact. This method may involve hazardous materials, operations,
and equipment. This test method does not purport to address all of
the safety problems associated with its use. It is the
responsibility of the user of this test method to establish
appropriate safety and health practices and to determine the
applicability of regulatory limitations in regards to the
performance of this test method.
5.2 Dimethylformamide is harmful if inhaled or absorbed through
the skin. The user should obtain relevant health and safety
information from the manufacturer. Dimethylformamide should be used
only with adequate ventilation. Avoid contact with skin, eyes, and
clothing. In case of contact, immediately flush skin or eyes with
plenty of water for at least 15 minutes. If eyes are affected,
consult a physician. Remove and wash contaminated clothing before
reuse.
5.3 User's manuals for the gas chromatograph and other related
equipment should be consulted for specific precautions to be taken
related to their use.
6. Equipment and Supplies Note:
Certified product data sheets (CPDS) may also include
information relevant to the analysis of the coating sample
including, but not limited to, separation column, oven temperature,
carrier gas, injection port temperature, extraction solvent, and
internal standard.
6.1 Sample Collection.
6.1.1 Sampling Containers. Dual-seal sampling containers, four
to eight fluid ounce capacity, should be used to collect the
samples. Glass sample bottles or plastic containers with volatile
organic compound (VOC) impermeable walls must be used for corrosive
substances (e.g., etch primers and certain coating catalysts
such as methyl ethyl ketone (MEK) peroxide). Sample containers,
caps, and inner seal liners must be inert to the compounds in the
sample and must be selected on a case-by-case basis.
6.1.1.1 Other routine sampling supplies needed include
waterproof marking pens, tubing, scrappers/spatulas, clean rags,
paper towels, cooler/ice, long handle tongs, and mixing/stirring
paddles.
6.1.2 Personal safety equipment needed includes eye protection,
respiratory protection, a hard hat, gloves, steel toe shoes,
etc.
6.1.3 Shipping supplies needed include shipping boxes, packing
material, shipping labels, strapping tape, etc.
6.1.4 Data recording forms and labels needed include coating
data sheets and sample can labels.
Note:
The actual requirements will depend upon the conditions existing
at the source sampled.
6.2 Laboratory Equipment and Supplies.
6.2.1 Gas Chromatograph (GC). Any instrument equipped with a
flame ionization detector and capable of being temperature
programmed may be used. Optionally, other types of detectors (e.g.,
a mass spectrometer), and any necessary interfaces, may be used
provided that the detector system yields an appropriate and
reproducible response to the analytes in the injected sample.
Autosampler injection may be used, if available.
6.2.2 Recorder. If available, an electronic data station or
integrator may be used to record the gas chromatogram and
associated data. If a strip chart recorder is used, it must meet
the following criteria: A 1 to 10 millivolt (mV) linear response
with a full scale response time of 2 seconds or less and a maximum
noise level of ±0.03 percent of full scale. Other types of
recorders may be used as appropriate to the specific detector
installed provided that the recorder has a full scale response time
of 2 seconds or less and a maximum noise level of ±0.03 percent of
full scale.
6.2.3 Column. The column must be constructed of materials that
do not react with components of the sample (e.g., fused
silica, stainless steel, glass). The column should be of
appropriate physical dimensions (e.g., length, internal
diameter) and contain sufficient suitable stationary phase to allow
separation of the analytes. DB-5, DB-Wax, and FFAP columns are
commonly used for paint analysis; however, it is the responsibility
of each analyst to select appropriate columns and stationary
phases.
6.2.4 Tube and Tube Fittings. Supplies to connect the GC and gas
cylinders.
6.2.5 Pressure Regulators. Devices used to regulate the pressure
between gas cylinders and the GC.
6.2.6 Flow Meter. A device used to determine the carrier gas
flow rate through the GC. Either a digital flow meter or a soap
film bubble meter may be used to measure gas flow rates.
6.2.7 Septa. Seals on the GC injection port through which liquid
or gas samples can be injected using a syringe.
6.2.8 Liquid Charging Devices. Devices used to inject samples
into the GC such as clean and graduated 1, 5, and 10 microliter
(µl) capacity syringes.
6.2.9 Vials. Containers that can be sealed with a septum in
which samples may be prepared or stored. The recommended size is 25
ml capacity. Mininert ® valves have been found satisfactory and are
available from Pierce Chemical Company, Rockford, Illinois.
6.2.10 Balance. Device used to determine the weights of
standards and samples. An analytical balance capable of accurately
weighing to 0.0001 g is required.
7. Reagents and Standards
7.1 Purity of Reagents. Reagent grade chemicals shall be used in
all tests. Unless otherwise specified, all reagents shall conform
to the specifications of the Committee on Analytical Reagents of
the American Chemical Society, where such specifications are
available. Other grades may be used provided it is first
ascertained that the reagent is of sufficient purity to permit its
use without lessening the accuracy of determination.
7.2 Carrier Gas. Helium carrier gas shall have a purity of
99.995 percent or higher. High purity nitrogen may also be used.
Other carrier gases that are appropriate for the column system and
analyte may also be used. Ultra-high purity grade hydrogen gas and
zero-grade air shall be used for the flame ionization detector.
7.3 Dimethylformamide (DMF). Solvent for all standards and
samples. Some other suitable solvent may be used if DMF is not
compatible with the sample or coelutes with a target analyte.
Note:
DMF may coelute with ethylbenzene or p-xylene under the
conditions described in the note under Section 6.2.3.
7.4 Internal Standard Materials. The internal standard material
is used in the quantitation of the analytes for this method. It
shall be gas chromatography spectrophotometric quality or, if this
grade is not available, the highest quality available. Obtain the
assay for the internal standard material and maintain at that
purity during use. The recommended internal standard material is
1-propanol; however, selection of an appropriate internal standard
material for the particular coating and GC conditions used is the
responsibility of each analyst.
7.5 Reference Standard Materials. The reference standard
materials are the chemicals cited in Section 1.1 which are of known
identity and purity and which are used to assist in the
identification and quantification of the analytes of this method.
They shall be the highest quality available. Obtain the assays for
the reference standard materials and maintain at those purities
during use.
7.6 Stock Reference Standards. Stock reference standards are
dilutions of the reference standard materials that may be used on a
daily basis to prepare calibration standards, calibration check
standards, and quality control check standards. Stock reference
standards may be prepared from the reference standard materials or
purchased as certified solutions.
7.6.1 Stock reference standards should be prepared in
dimethylformamide for each analyte expected in the coating samples
to be analyzed. The concentrations of analytes in the stock
reference standards are not specified but must be adequate to
prepare the calibration standards required in the method. A stock
reference standard may contain more than one analyte provided all
analytes are chemically compatible and no analytes coelute. The
actual concentrations prepared must be known to within 0.1 percent
(e.g., 0.1000 ±0.0001 g/g solution). The following procedure is
suggested. Place about 35 ml of dimethylformamide into a tared
ground-glass stoppered 50 ml volumetric flask. Weigh the flask to
the nearest 0.1 mg. Add 12.5 g of the reference standard material
and reweigh the flask. Dilute to volume with dimethylformamide and
reweigh. Stopper the flask and mix the contents by inverting the
flask several times. Calculate the concentration in grams per gram
of solution from the net gain in weights, correcting for the
assayed purity of the reference standard material.
Note:
Although a glass-stoppered volumetric flask is convenient, any
suitable glass container may be used because stock reference
standards are prepared by weight.
7.6.2 Transfer the stock reference standard solution into one or
more Teflon-sealed screw-cap bottles. Store, with minimal
headspace, at −10 °C to 0 °C and protect from light.
7.6.3 Prepare fresh stock reference standards every six months,
or sooner if analysis results from daily calibration check
standards indicate a problem. Fresh stock reference standards for
very volatile HAP's may have to be prepared more frequently.
7.7 Calibration Standards. Calibration standards are used to
determine the response of the detector to known amounts of
reference material. Calibration standards must be prepared at a
minimum of three concentration levels from the stock reference
standards (see Section 7.6). Prepare the calibration standards in
dimethylformamide (see Section 7.3). The lowest concentration
standard should contain a concentration of analyte equivalent
either to a concentration of no more than 0.01% of the analyte in a
coating or to a concentration that is lower than the actual
concentration of the analyte in the coating, whichever
concentration is higher. The highest concentration standard should
contain a concentration of analyte equivalent to slightly more than
the highest concentration expected for the analyte in a coating.
The remaining calibration standard should contain a concentration
of analyte roughly at the midpoint of the range defined by the
lowest and highest concentration calibration standards. The
concentration range of the standards should thus correspond to the
expected range of analyte concentrations in the prepared coating
samples (see Section 11.5). Each calibration standard should
contain each analyte for detection by this method expected in the
actual coating samples (e.g., some or all of the compounds listed
in Section 1.1 may be included). Each calibration standard should
also contain an appropriate amount of internal standard material
(response for the internal standard material is within 25 to 75
percent of full scale on the attenuation setting for the particular
reference standard concentration level). Calibration Standards
should be stored for 1 week only in sealed vials with minimal
headspace. If the stock reference standards were prepared as
specified in Section 7.6, the calibration standards may be prepared
by either weighing each addition of the stock reference standard or
by adding known volumes of the stock reference standard and
calculating the mass of the standard reference material added.
Alternative 1 (Section 7.7.1) specifies the procedure to be
followed when the stock reference standard is added by volume.
Alternative 2 (Section 7.7.2) specifies the procedure to be
followed when the stock reference standard is added by weight.
Note:
To assist with determining the appropriate amount of internal
standard to add, as required here and in other sections of this
method, the analyst may find it advantageous to prepare a curve
showing the area response versus the amount of internal standard
injected into the GC.
7.7.1 Preparation Alternative 1. Determine the amount of each
stock reference standard and dimethylformamide solvent needed to
prepare approximately 25 ml of the specific calibration
concentration level desired. To a tared 25 ml vial that can be
sealed with a crimp-on or Mininert ® valve, add the total amount of
dimethylformamide calculated to be needed. As quickly as practical,
add the calculated amount of each stock reference standard using
new pipets (or pipet tips) for each stock reference standard.
Reweigh the vial and seal it. Using the known weights of the
standard reference materials per ml in the stock reference
standards, the volumes added, and the total weight of all reagents
added to the vial, calculate the weight percent of each standard
reference material in the calibration standard prepared. Repeat
this process for each calibration standard to be prepared.
7.7.2 Preparation Alternative 2. Determine the amount of each
stock reference standard and dimethylformamide solvent needed to
prepare approximately 25 ml of the specific calibration
concentration level desired. To a tared 25 ml vial that can be
sealed with a crimp-on or Mininert ® valve, add the total amount of
dimethylformamide calculated to be needed. As quickly as practical,
add the calculated amount of a stock reference standard using a new
pipet (or pipet tip) and reweigh the vial. Repeat this process for
each stock reference standard to be added. Seal the vial after
obtaining the final weight. Using the known weight percents of the
standard reference materials in the stock reference standards, the
weights of the stock reference standards added, and the total
weight of all reagents added to the vial, calculate the weight
percent of each standard reference material in the calibration
standard prepared. Repeat this process for each calibration
standard to be prepared.
8. Sample Collection, Preservation, Transport, and Storage
8.1 Copies of material safety data sheets (MSDS's) for each
sample should be obtained prior to sampling. The MSDS's contain
information on the ingredients, and physical and chemical
properties data. The MSDS's also contain recommendations for proper
handling or required safety precautions. Certified product data
sheets (CPDS) may also include information relevant to the analysis
of the coating sample including, but not limited to, separation
column, oven temperature, carrier gas, injection port temperature,
extraction solvent, and internal standard.
8.2 A copy of the blender's worksheet can be requested to obtain
data on the exact coating being sampled. A blank coating data sheet
form (see Section 18) may also be used. The manufacturer's
formulation information from the product data sheet should also be
obtained.
8.3 Prior to sample collection, thoroughly mix the coating to
ensure that a representative, homogeneous sample is obtained. It is
preferred that this be accomplished using a coating can shaker or
similar device; however, when necessary, this may be accomplished
using mechanical agitation or circulation systems.
8.3.1 Water-thinned coatings tend to incorporate or entrain air
bubbles if stirred too vigorously; mix these types of coatings
slowly and only as long as necessary to homogenize.
8.3.2 Each component of multicomponent coatings that harden when
mixed must be sampled separately. The component mix ratios must be
obtained at the facility at the time of sampling and submitted to
the analytical laboratory.
8.4 Sample Collection. Samples must be collected in a manner
that prevents or minimizes loss of volatile components and that
does not contaminate the coating reservoir. A suggested procedure
is as follows. Select a sample collection container which has a
capacity at least 25 percent greater than the container in which
the sample is to be transported. Make sure both sample containers
are clean and dry. Using clean, long-handled tongs, turn the sample
collection container upside down and lower it into the coating
reservoir. The mouth of the sample collection container should be
at approximately the midpoint of the reservoir (do not take the
sample from the top surface). Turn the sample collection container
over and slowly bring it to the top of the coating reservoir.
Rapidly pour the collected coating into the sample container,
filling it completely. It is important to fill the sample container
completely to avoid any loss of volatiles due to volatilization
into the headspace. Return any unused coating to the reservoir or
dispose as appropriate.
Note:
If a company requests a set of samples for its own analysis, a
separate set of samples, using new sample containers, should be
taken at the same time.
8.5 Once the sample is collected, place the sample container on
a firm surface and insert the inner seal in the container by
placing the seal inside the rim of the container, inverting a screw
cap, and pressing down on the screw cap which will evenly force the
inner seal into the container for a tight fit. Using clean towels
or rags, remove all residual coating material from the outside of
the sample container after inserting the inner seal. Screw the cap
onto the container.
8.5.1 Affix a sample label (see Section 18) clearly identifying
the sample, date collected, and person collecting the sample.
8.5.2 Prepare the sample for transportation to the laboratory.
The sample should be maintained at the coating's recommended
storage temperature specified on the Material Safety Data Sheet,
or, if no temperature is specified, the sample should be maintained
within the range of 5 °C to 38 °C.
8.9 The shipping container should adhere to U.S. Department of
Transportation specification DOT 12-B. Coating samples are
considered hazardous materials; appropriate shipping procedures
should be followed.
9. Quality Control
9.1 Laboratories using this method should operate a formal
quality control program. The minimum requirements of the program
should consist of an initial demonstration of laboratory capability
and an ongoing analysis of blanks and quality control samples to
evaluate and document quality data. The laboratory must maintain
records to document the quality of the data generated. When results
indicate atypical method performance, a quality control check
standard (see Section 9.4) must be analyzed to confirm that the
measurements were performed in an in-control mode of operation.
9.2 Before processing any samples, the analyst must demonstrate,
through analysis of a reagent blank, that there are no
interferences from the analytical system, glassware, and reagents
that would bias the sample analysis results. Each time a set of
analytical samples is processed or there is a change in reagents, a
reagent blank should be processed as a safeguard against chronic
laboratory contamination. The blank samples should be carried
through all stages of the sample preparation and measurement
steps.
9.3 Required instrument quality control parameters are found in
the following sections:
9.3.1 Baseline stability must be demonstrated to be ≤5 percent
of full scale using the procedures given in Section 10.1.
9.3.2 The GC calibration is not valid unless the retention time
(RT) for each analyte at each concentration is within ±0.05 min of
the retention time measured for that analyte in the stock
standard.
9.3.3 The retention time (RT) of any sample analyte must be
within ±0.05 min of the average RT of the analyte in the
calibration standards for the analyte to be considered tentatively
identified.
9.3.4 The GC system must be calibrated as specified in Section
10.2.
9.3.5 A one-point daily calibration check must be performed as
specified in Section 10.3.
9.4 To establish the ability to generate results having
acceptable accuracy and precision, the analyst must perform the
following operations.
9.4.1 Prepare a quality control check standard (QCCS) containing
each analyte expected in the coating samples at a concentration
expected to result in a response between 25 percent and 75 percent
of the limits of the calibration curve when the sample is prepared
as described in Section 11.5. The QCCS may be prepared from
reference standard materials or purchased as certified solutions.
If prepared in the laboratory, the QCCS must be prepared
independently from the calibration standards.
9.4.2 Analyze three aliquots of the QCCS according to the method
beginning in Section 11.5.3 and calculate the weight percent of
each analyte using Equation 1, Section 12.
9.4.3 Calculate the mean weight percent (X ) for each analyte
from the three results obtained in Section 9.4.2.
9.4.4 Calculate the percent accuracy for each analyte using the
known concentrations (Ti) in the QCCS using Equation 3, Section
12.
9.4.5 Calculate the percent relative standard deviation (percent
RSD) for each analyte using Equation 7, Section 12, substituting
the appropriate values for the relative response factors (RRF's) in
said equation.
9.4.6 If the percent accuracy (Section 9.4.4) for all analytes
is within the range 90 percent to 110 percent and the percent RSD
(Section 9.4.5) for all analytes is ≤20 percent, system performance
is acceptable and sample analysis may begin. If these criteria are
not met for any analyte, then system performance is not acceptable
for that analyte and the test must be repeated for those analytes
only. Repeated failures indicate a general problem with the
measurement system that must be located and corrected. In this
case, the entire test, beginning at Section 9.4.1, must be repeated
after the problem is corrected.
9.5 Great care must be exercised to maintain the integrity of
all standards. It is recommended that all standards be stored at
−10 °C to 0 °C in screw-cap amber glass bottles with Teflon
liners.
9.6 Unless otherwise specified, all weights are to be recorded
within 0.1 mg.
10. Calibration and Standardization.
10.1 Column Baseline Drift. Before each calibration and series
of determinations and before the daily calibration check, condition
the column using procedures developed by the laboratory or as
specified by the column supplier. Operate the GC at initial (i.e.,
before sample injection) conditions on the lowest attenuation to be
used during sample analysis. Adjust the recorder pen to zero on the
chart and obtain a baseline for at least one minute. Initiate the
GC operating cycle that would be used for sample analysis. On the
recorder chart, mark the pen position at the end of the simulated
sample analysis cycle. Baseline drift is defined as the absolute
difference in the pen positions at the beginning and end of the
cycle in the direction perpendicular to the chart movement.
Calculate the percent baseline drift by dividing the baseline drift
by the chart width representing full-scale deflection and multiply
the result by 100.
10.2 Calibration of GC. Bring all stock standards and
calibration standards to room temperature while establishing the GC
at the determined operating conditions.
10.2.1 Retention Times (RT's) for Individual Compounds.
Note:
The procedures of this subsection are required only for the
initial calibration. However, it is good laboratory practice to
follow these procedures for some or all analytes before each
calibration. The procedures were written for chromatograms output
to a strip chart recorder. More modern instruments (e.g.,
integrators and electronic data stations) determine and print out
or display retention times automatically.
The RT for each analyte should be determined before calibration.
This provides a positive identification for each peak observed from
the calibration standards. Inject an appropriate volume (see note
in Section 11.5.2) of one of the stock reference standards into the
gas chromatograph and record on the chart the pen position at the
time of the injection (see Section 7.6.1). Dilute an aliquot of the
stock reference standard as required in dimethylformamide to
achieve a concentration that will result in an on-scale response.
Operate the gas chromatograph according to the determined
procedures. Select the peak(s) that correspond to the analyte(s)
[and internal standard, if used] and measure the retention time(s).
If a chart recorder is used, measure the distance(s) on the chart
from the injection point to the peak maxima. These distances,
divided by the chart speed, are defined as the RT's of the analytes
in question. Repeat this process for each of the stock reference
standard solutions.
Note:
If gas chromatography with mass spectrometer detection (GC-MS)
is used, a stock reference standard may contain a group of
analytes, provided all analytes are adequately separated during the
analysis. Mass spectral library matching can be used to identify
the analyte associated with each peak in the gas chromatogram. The
retention time for the analyte then becomes the retention time of
its peak in the chromatogram.
10.2.2 Calibration. The GC must be calibrated using a minimum of
three concentration levels of each potential analyte. (See Section
7.7 for instructions on preparation of the calibration standards.)
Beginning with the lowest concentration level calibration standard,
carry out the analysis procedure as described beginning in Section
11.7. Repeat the procedure for each progressively higher
concentration level until all calibration standards have been
analyzed.
10.2.2.1 Calculate the RT's for the internal standard and for
each analyte in the calibration standards at each concentration
level as described in Section 10.2.1. The RT's for the internal
standard must not vary by more than 0.10 minutes. Identify each
analyte by comparison of the RT's for peak maxima to the RT's
determined in Section 10.2.1.
10.2.2.2 Compare the retention times (RT's) for each potential
analyte in the calibration standards for each concentration level
to the retention times determined in Section 10.2.1. The
calibration is not valid unless all RT's for all analytes meet the
criteria given in Section 9.3.2.
10.2.2.3 Tabulate the area responses and the concentrations for
the internal standard and each analyte in the calibration
standards. Calculate the response factor for the internal standard
(RFis) and the response factor for each compound relative to the
internal standard (RRF) for each concentration level using
Equations 5 and 6, Section 12.
10.2.2.4 Using the RRF's from the calibration, calculate the
percent relative standard deviation (percent RSD) for each analyte
in the calibration standard using Equation 7, Section 12. The
percent RSD for each individual calibration analyte must be
less than 15 percent. This criterion must be met in order
for the calibration to be valid. If the criterion is met, the mean
RRF's determined above are to be used until the next
calibration.
10.3 Daily Calibration Checks. The calibration curve (Section
10.2.2) must be checked and verified at least once each day that
samples are analyzed. This is accomplished by analyzing a
calibration standard that is at a concentration near the midpoint
of the working range and performing the checks in Sections 10.3.1,
10.3.2, and 10.3.3.
10.3.1 For each analyte in the calibration standard, calculate
the percent difference in the RRF from the last calibration using
Equation 8, Section 12. If the percent difference for each
calibration analyte is less than 10 percent, the last calibration
curve is assumed to be valid. If the percent difference for any
analyte is greater than 5 percent, the analyst should consider this
a warning limit. If the percent difference for any one calibration
analyte exceeds 10 percent, corrective action must be taken. If no
source of the problem can be determined after corrective action has
been taken, a new three-point (minimum) calibration must be
generated. This criterion must be met before quantitative analysis
begins.
10.3.2 If the RFis for the internal standard changes by more
than ±20 percent from the last daily calibration check, the system
must be inspected for malfunctions and corrections made as
appropriate.
10.3.3 The retention times for the internal standard and all
calibration check analytes must be evaluated. If the retention time
for the internal standard or for any calibration check analyte
changes by more than 0.10 min from the last calibration, the system
must be inspected for malfunctions and corrections made as
required.
11. Procedure
11.1 All samples and standards must be allowed to warm to room
temperature before analysis. Observe the given order of ingredient
addition to minimize loss of volatiles.
11.2 Bring the GC system to the determined operating conditions
and condition the column as described in Section 10.1.
Note:
The temperature of the injection port may be an especially
critical parameter. Information about the proper temperature may be
found on the CPDS.
11.3 Perform the daily calibration checks as described in
Section 10.3. Samples are not to be analyzed until the criteria in
Section 10.3 are met.
11.4 Place the as-received coating sample on a paint shaker, or
similar device, and shake the sample for a minimum of 5 minutes to
achieve homogenization.
11.5 Note: The steps in this section must be performed rapidly
and without interruption to avoid loss of volatile organics. These
steps must be performed in a laboratory hood free from solvent
vapors. All weights must be recorded to the nearest 0.1 mg.
11.5.1 Add 16 g of dimethylformamide to each of two tared vials
(A and B) capable of being septum sealed.
11.5.2 To each vial add a weight of coating that will result in
the response for the major constituent being in the upper half of
the linear range of the calibration curve.
Note:
The magnitude of the response obviously depends on the amount of
sample injected into the GC as specified in Section 11.8. This
volume must be the same as used for preparation of the calibration
curve, otherwise shifts in compound retention times may occur. If a
sample is prepared that results in a response outside the limits of
the calibration curve, new samples must be prepared; changing the
volume injected to bring the response within the calibration curve
limits is not permitted.
11.5.3 Add a weight of internal standard to each vial (A and B)
that will result in the response for the internal standard being
between 25 percent and 75 percent of the linear range of the
calibration curve.
11.5.4 Seal the vials with crimp-on or Mininert ® septum
seals.
11.6 Shake the vials containing the prepared coating samples for
60 seconds. Allow the vials to stand undisturbed for ten minutes.
If solids have not settled out on the bottom after 10 minutes, then
centrifuge at 1,000 rpm for 5 minutes. The analyst also has the
option of injecting the sample without allowing the solids to
settle.
11.7 Analyses should be conducted in the following order: daily
calibration check sample, method blank, up to 10 injections from
sample vials (i.e., one injection each from up to five pairs
of vials, which corresponds to analysis of 5 coating samples).
11.8 Inject the prescribed volume of supernatant from the
calibration check sample, the method blank, and the sample vials
onto the chromatographic column and record the chromatograms while
operating the system under the specified operating conditions.
Note:
The analyst has the option of injecting the unseparated
sample.
12. Data Analysis and Calculations
12.1 Qualitative Analysis. An analyte (e.g., those cited in
Section 1.1) is considered tentatively identified if two criteria
are satisfied: (1) elution of the sample analyte within ±0.05 min
of the average GC retention time of the same analyte in the
calibration standard; and (2) either (a) confirmation of the
identity of the compound by spectral matching on a gas
chromatograph equipped with a mass selective detector or (b)
elution of the sample analyte within ±0.05 min of the average GC
retention time of the same analyte in the calibration standard
analyzed on a dissimilar GC column.
12.1.1 The RT of the sample analyte must meet the criteria
specified in Section 9.3.3.
12.1.2 When doubt exists as to the identification of a peak or
the resolution of two or more components possibly comprising one
peak, additional confirmatory techniques (listed in Section 12.1)
must be used.
12.2 Quantitative Analysis. When an analyte has been identified,
the quantification of that compound will be based on the internal
standard technique.
12.2.1 A single analysis consists of one injection from each of
two sample vials (A and B) prepared using the same coating.
Calculate the concentration of each identified analyte in the
sample as follows:
12.2.2 Report results for duplicate analysis (sample vials A and
B) without correction.
12.3 Precision Data. Calculate the percent difference between
the measured concentrations of each analyte in vials A and B as
follows.
12.3.1 Calculate the weight percent of the analyte in each of
the two sample vials as described in Section 12.2.1.
12.3.2 Calculate the percent difference for each analyte as:
![]()
where Ai and Bi are the measured concentrations
of the analyte in vials A and B.
12.4 Calculate the percent accuracy for analytes in the QCCS
(See Section 9.4) as follows:
![]()
where Xx is the mean measured value and Tx is
the known true value of the analyte in the QCCS.
12.5 Obtain retention times (RT's) from data station or
integrator or, for chromatograms from a chart recorder, calculate
the RT's for analytes in the calibration standards (See Section
10.2.2.2) as follows:
12.6 Calculate the response factor for the internal standard
(See Section 10.2.2.3) as follows:
![]()
where:
Ais = Area response of the internal standard.
Cis = Weight percent of the internal standard.
12.7 Calculate the relative response factors for analytes in the
calibration standards (See Section 10.2.2.3) as follows:
where:
RRFx = Relative response factor for an individual analyte.
Ax = Area response of the analyte being measured.
Cx = Weight percent of the analyte being measured.
12.8 Calculate the percent relative standard deviation of the
relative response factors for analytes in the calibration standards
(See Section 10.2.2.4) as follows:
12.9 Calculate the percent difference in the relative response
factors between the calibration curve and the daily calibration
checks (See Section 10.3) as follows:
![]()
13. Measurement of Reaction Byproducts That are
HAP [Reserved] 14. Method Performance [Reserved] 15. Pollution
Prevention [Reserved] 16. Waste Management
16.1 The coating samples and laboratory standards and reagents
may contain compounds which require management as hazardous waste.
It is the laboratory's responsibility to ensure all wastes are
managed in accordance with all applicable laws and regulations.
16.2 To avoid excessive laboratory waste, obtain only enough
sample for laboratory analysis.
16.3 It is recommended that discarded waste coating solids, used
rags, used paper towels, and other nonglass or nonsharp waste
materials be placed in a plastic bag before disposal. A separate
container, designated “For Sharp Objects Only,” is recommended for
collection of discarded glassware and other sharp-edge items used
in the laboratory. It is recommended that unused or excess samples
and reagents be placed in a solvent-resistant plastic or metal
container with a lid or cover designed for flammable liquids. This
container should not be stored in the area where analytical work is
performed. It is recommended that a record be kept of all compounds
placed in the container for identification of the contents upon
disposal.
17. References
1. Clean Air Act Amendments, Public Law 101-549, Titles I-XI,
November, 1990.
2. Standard Test Method for Water Content of Water-Reducible
Paints by Direct Injection into a Gas Chromatograph. ASTM
Designation D3792-79.
3. Standard Practice for Sampling Liquid Paints and Related
Pigment Coatings. ASTM Designation D3925-81.
4. Standard Test Method for Determination of Dichloromethane and
1,1,1-Trichloroethane in Paints and Coatings by Direct Injection
into a Gas Chromatograph. ASTM Designation D4457-02.
5. Standard Test Method for Determining the Unreacted Monomer
Content of Latexes Using Capillary Column Gas Chromatography. ASTM
Designation D4827-03.
6. Standard Test Method for Determining Unreacted Monomer
Content of Latexes Using Gas-Liquid Chromatography, ASTM
Designation D4747-02.
7. Method 301 - “Field Validation of Pollutant Measurement
Methods from Various Waste Media,” 40 CFR 63, Appendix A.
8. “Reagent Chemicals, American Chemical Society
Specifications,” American Chemical Society, Washington, DC. For
suggestions on the testing of reagents not listed by the American
Chemical Society, see “Reagent Chemicals and Standards” by Joseph
Rosin, D. Van Nostrand Co., Inc., New York, NY and the “United
States Pharmacopeia.”
18. Tables, Diagrams, Flowcharts, and Validation Data Agency:
Inspector: Date/Time: Sample ID#: Source ID: Coating Name/Type:
Plant Witness: Type Analysis Required: Special Handling: Sample
Container Label Coating Data Date: Source:
Data |
Sample ID No. |
Sample ID No. |
Coating: |
|
|
Supplier
Name |
|
|
Name and Color
of Coating |
|
|
Type of Coating
(primer, clearcoat, etc.) |
|
|
Identification
Number for Coating |
|
|
Coating Density
(lbs/gal) |
|
|
Total Volatiles
Content (wt percent) |
|
|
Water Content
(wt percent) |
|
|
Exempt Solvents
Content (wt percent) |
|
|
VOC Content (wt
percent) |
|
|
Solids Content
(vol percent) |
|
|
Diluent
Properties: |
|
|
Name |
|
|
Identification
Number |
|
|
Diluent Solvent
Density (lbs/gal) |
|
|
VOC Content (wt
percent) |
|
|
Water Content
(wt percent) |
|
|
Exempt Solvent
Content (wt percent) |
|
|
Diluent/Solvent
Ratio (gal diluent solvent/gal coating) |
|
|
Stock Reference Standard Name of Reference Material: Supplier Name:
Lot Number: Purity: Name of Solvent Material:
Dimethylformamide Supplier Name: Lot Number: Purity: Date
Prepared: Prepared By: Notebook/page no.:
1. Weight Empty
Flask |
____,g |
2. Weight Plus
DMF |
____,g |
3. Weight Plus
Reference Material |
____,g |
4. Weight After
Made to Volume |
____,g |
5. Weight DMF
(lines 2-1 + 3-4) |
____,g |
6. Weight Ref.
Material (lines 3-2) |
____,g |
7. Corrected
Weight of Reference Material (line 6 times purity) |
____,g |
8. Fraction
Reference Material in Standard (Line 7 ÷ Line 5) soln |
____,g/g |
9. Total Volume of
Standard Solution |
____, ml |
10. Weight
Reference Material per ml of Solution (Line 7 ÷ Line 9) |
____,g/ml |
Laboratory ID No.
for this Standard |
____ |
Expiration Date
for this Standard |
____ |
CALIBRATION STANDARD Date Prepared: Date Expires: Prepared By:
Notebook/page: Calibration Standard Identification No.:
Final Weight Flask
Plus Reagents |
____, g |
Weight Empty
Flask |
____, g |
Total Weight Of
Reagents |
____, g |
Analyte name
a |
Stock reference
standard ID No. |
Amount of stock
reference standard added (by volume or by weight) |
Calculated weight
analyte added, g |
Weight percent
analyte in calibration standard b |
Volume added, ml |
Amount in standard, g/ml |
Weight added, g |
Amount in standard, g/g
soln |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Quality Control Check Standard Date Prepared: Date Expires:
Prepared By: Notebook/page: Quality Control Check Standard
Identification No.:
Final Weight Flask
Plus Reagents |
____,g |
Weight Empty
Flask |
____,g |
Total Weight Of
Reagents |
____,g |
Analyte name
a |
Stock reference
standard ID No. |
Amount of stock
reference standard added (by volume or by weight) |
Calculated weight
analyte added, g |
Weight percent
analyte in QCC standard b |
Volume added, ml |
Amount in standard, g/ml |
Weight added, g |
Amount in standard, g/g
soln |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Quality Control Check Standard Analysis Date OCCS Analyzed: OCCS
Identification No. Analyst: QCC Expiration Date:
Analyte |
Weight percent
determined |
Mean Wt
percent |
Percent
accuracx |
Percent RSD |
Meets criteria in
Section 9.4.6 |
Run 1 |
Run 2 |
Run 3 |
Percent
accuracy |
Percent RSD |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Calibration of Gas Chromatograph Calibration Date: Calibrated By:
Part 1 - Retention Times for Individual
Analytes
Analyte |
Stock standard.
ID No. |
Recorder chart
speed |
Distance from
injection point to peak maximum |
Retention time,
minutes a |
Inches/min. |
cm/min. |
Inches |
Centimeters |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
CALIBRATION OF GAS CHROMATOGRAPH Calibration Date: Calibrated By:
Part 2 - Analysis of Calibration
Standards
Analyte |
Calib. STD ID No. |
Calib. STD ID No. |
Calib. STD ID No. |
Name: |
|
|
|
Conc. in
STD |
|
|
|
Area
Response |
|
|
|
RT |
|
|
|
Name: |
|
|
|
Conc. in
STD |
|
|
|
Area
Response |
|
|
|
RT |
|
|
|
Name: |
|
|
|
Conc. in
STD |
|
|
|
Area
Response |
|
|
|
RT |
|
|
|
Name: |
|
|
|
Conc. in
STD |
|
|
|
Area
Response |
|
|
|
RT |
|
|
|
Name: |
|
|
|
Conc. in
STD |
|
|
|
Area
Response |
|
|
|
RT |
|
|
|
Name: |
|
|
|
Conc. in
STD |
|
|
|
Area
Response |
|
|
|
RT |
|
|
|
Name: |
|
|
|
Conc. in
STD |
|
|
|
Area
Response |
|
|
|
RT |
|
|
|
Name: |
|
|
|
Conc. in
STD |
|
|
|
Area
Response |
|
|
|
RT |
|
|
|
Internal Standard
Name: |
|
|
|
Conc. in
STD |
|
|
|
Area
Response |
|
|
|
RT |
|
|
|
Calibration of Gas Chromatograph Calibration Date: Calibrated By:
Part 3 - Data Analysis for Calibration
Standards
Analyte |
Calib. STD ID |
Calib. STD ID |
Calib. STD ID |
Mean |
percent RSD of RF |
Is RT within ±0.05 min of RT
for stock? (Y/N) |
Is percent RSD <30%
(Y/N) |
Name: |
|
|
|
|
|
|
|
RT |
|
|
|
|
|
|
|
RF |
|
|
|
|
|
|
|
Name: |
|
|
|
|
|
|
|
RT |
|
|
|
|
|
|
|
RF |
|
|
|
|
|
|
|
Name: |
|
|
|
|
|
|
|
RT |
|
|
|
|
|
|
|
RF |
|
|
|
|
|
|
|
Name: |
|
|
|
|
|
|
|
RT |
|
|
|
|
|
|
|
RF |
|
|
|
|
|
|
|
Name: |
|
|
|
|
|
|
|
RT |
|
|
|
|
|
|
|
RF |
|
|
|
|
|
|
|
Name: |
|
|
|
|
|
|
|
RT |
|
|
|
|
|
|
|
RF |
|
|
|
|
|
|
|
Name: |
|
|
|
|
|
|
|
RT |
|
|
|
|
|
|
|
RF |
|
|
|
|
|
|
|
Daily Calibration Check Date: Analyst: Calibration Check Standard
ID No.: Expiration Date:
Analyte |
Retention Time
(RT) |
Response Factor
(RF) |
Last |
This |
Difference a |
Last |
This |
Difference b |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Sample Analysis Vial A ID No.: Vial B ID No.: Analyzed By: Date:
Sample preparation
information |
Vial A (g) |
Vial B (g) |
Measured: |
|
|
wt empty
via |
|
|
wt plus
DMF |
|
|
wt plus
sample |
|
|
wt plus
internal |
|
|
standard |
|
|
Calculated: |
|
|
wt DMF |
|
|
wt sample |
|
|
wt internal
standard |
|
|
Analysis Results: Duplicate Samples
Analyte |
Area
response |
RF |
Wt percent in
sample |
Vial A |
Vial B |
Vial A |
Vial B |
Average |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Internal
Standard |
|
|
|
|
|
|
Method 312A - Determination of Styrene in Latex Styrene-Butadiene
Rubber, Through Gas Chromatography 1. Scope and Application
1.1 This method describes a procedure for determining parts per
million (ppm) styrene monomer (CAS No. 100-42-5) in aqueous
samples, including latex samples and styrene stripper water.
1.2 The sample is separated in a gas chromatograph equipped with
a packed column and a flame ionization detector.
2.0 Summary of Method
2.1 This method utilizes a packed column gas chromatograph with
a flame ionization detector to determine the concentration of
residual styrene in styrene butadiene rubber (SBR) latex
samples.
3.0 Definitions
3.1 The definitions are included in the text as needed.
4.0 Interferences
4.1 In order to reduce matrix effects and emulsify the styrene,
similar styrene free latex is added to the internal standard. There
are no known interferences.
4.2 The operating parameters are selected to obtain resolution
necessary to determine styrene monomer concentrations in latex.
5.0 Safety
5.1 It is the responsibility of the user of this procedure to
establish appropriate safety and health practices.
6.0 Equipment and Supplies
6.1 Adjustable bottle-top dispenser, set to deliver 3 ml. (for
internal standard), Brinkmann Dispensette, or equivalent.
6.2 Pipettor, set to 10 ml., Oxford Macro-set, or
equivalent.
6.3 Volumetric flask, 100-ml, with stopper.
6.4 Hewlett Packard Model 5710A dual channel gas chromatograph
equipped with flame ionization detector.
6.4.1 11 ft. × 1/8 in. stainless steel column packed with 10%
TCEP on 100/120 mesh Chromosorb P, or equivalent.
6.4.2 Perkin Elmer Model 023 strip chart recorder, or
equivalent.
6.5 Helium carrier gas, zero grade.
6.6 Liquid syringe, 25-µl.
6.7 Digital MicroVAX 3100 computer with VG Multichrom software,
or equivalent data handling system.
6.6 Wire Screens, circular, 70-mm, 80-mesh diamond weave.
6.7 DEHA - (N,N-Diethyl hydroxylamine), 97 + % purity, CAS No.
3710-84-7
6.8 p-Dioxane, CAS No. 123-91-1
7.0 Reagents and Standards
7.1 Internal standard preparation.
7.1.1 Pipette 5 ml p-dioxane into a 1000-ml volumetric flask and
fill to the mark with distilled water and mix thoroughly.
7.2 Calibration solution preparation.
7.2.1 Pipette 10 ml styrene-free latex (eg: NBR latex) into a
100-ml volumetric flask.
7.2.2 Add 3 ml internal standard (section 7.1.1 of this
method).
7.2.3 Weigh exactly 10 µl fresh styrene and record the
weight.
7.2.4 Inject the styrene into the flask and mix well.
7.2.5 Add 2 drops of DEHA, fill to the mark with water and mix
well again.
7.2.6 Calculate concentration of the calibration solution as
follows:
mg/l styrene = (mg styrene added)/0.1 L 8.0 Sample Collection,
Preservation, and Storage
8.1 A representative SBR emulsion sample should be caught in a
clean, dry 6-oz. teflon lined glass container. Close it properly to
assure no sample leakage.
8.2 The container should be labeled with sample identification,
date and time.
9.0 Quality Control
9.1 The instrument is calibrated by injecting calibration
solution (Section 7.2 of this method) five times.
9.2 The retention time for components of interest and relative
response of monomer to the internal standard is determined.
9.3 Recovery efficiency must be determined once for each sample
type and whenever modifications are made to the method.
9.3.1 A set of six latex samples shall be collected. Two samples
shall be prepared for analysis from each sample. Each sample shall
be analyzed in duplicate.
9.3.2 The second set of six latex samples shall be analyzed in
duplicate before spiking each sample with approximately 1000 ppm
styrene. The spiked samples shall be analyzed in duplicate.
9.3.3 For each hydrocarbon, calculate the average recovery
efficiency (R) using the following equations:
where: R=Σ(Rn)/6 where: Rn = (cns−cv)/Sn n = sample number cns =
concentration of compound measured in spiked sample number n. cnu =
concentration of compound measured in unspiked sample number n. Sn
= theoretical concentration of compound spiked into sample n.
9.3.4 A value of R between 0.70 and 1.30 is acceptable.
9.3.5 R is used to correct all reported results for each
compound by dividing the measured results of each compound by the R
for that compound for the same sample type.
10.0 Calibration and Instrument Settings
10.1 Injection port temperature, 250 °C.
10.2 Oven temperature, 110 °C, isothermal.
10.3 Carrier gas flow, 25 cc/min.
10.4 Detector temperature, 250 °C.
10.5 Range, 1X.
11.0 Procedure
11.1 Turn on recorder and adjust baseline to zero.
11.2 Prepare sample.
11.2.1 For latex samples, add 3 ml Internal Standard (section
7.1 of this method) to a 100-ml volumetric flask. Pipet 10 ml
sample into the flask using the Oxford pipettor, dilute to the
100-ml mark with water, and shake well.
11.2.2 For water samples, add 3 ml Internal Standard (section
7.1 of this method) to a 100-ml volumetric flask and fill to the
mark with sample. Shake well.
11.3 Flush syringe with sample.
11.4 Carefully inject 2 µl of sample into the gas chromatograph
column injection port and press the start button.
11.5 When the run is complete the computer will print a report
of the analysis.
12.0 Data Analysis and Calculation
12.1 For samples that are prepared as in section 11.2.1 of this
method:
ppm styrene = A × D Where: A = “ppm” readout from computer D =
dilution factor (10 for latex samples)
12.2 For samples that are prepared as in section 11.2.2 of this
method, ppm styrene is read directly from the computer.
13.0 Method Performance
13.1 This test has a standard deviation (1) of 3.3 ppm at 100
ppm styrene. The average Spike Recovery from six samples at 1000
ppm Styrene was 96.7 percent. The test method was validated using
926 ppm styrene standard. Six analysis of the same standard
provided average 97.7 percent recovery. Note: These are example
recoveries and do not replace quality assurance procedures in this
method.
14.0 Pollution Prevention
14.1 Waste generation should be minimized where possible. Sample
size should be an amount necessary to adequately run the
analysis.
15.0 Waste Management
15.1 All waste shall be handled in accordance with Federal and
State environmental regulations.
16.0 References and Publications
16.1 40 CFR 63 Appendix A - Method 301 Test Methods Field
Validation of Pollutant Measurement
16.2 DSM Copolymer Test Method T-3060, dated October 19, 1995,
entitled: Determination of Residual Styrene in Latex,
Leonard, C.D., Vora, N.M.et al
Method 312B - Determination of Residual Styrene in
Styrene-Butadiene (SBR) Rubber Latex by Capillary Gas
Chromatography 1.0 Scope
1.1 This method is applicable to SBR latex solutions.
1.2 This method quantitatively determines residual styrene
concentrations in SBR latex solutions at levels from 80 to 1200
ppm.
2.0 Principle of Method
2.1 A weighed sample of a latex solution is coagulated with an
ethyl alcohol (EtOH) solution containing a specific amount of
alpha-methyl styrene (AMS) as the internal standard. The extract of
this coagulation is then injected into a gas chromatograph and
separated into individual components. Quantification is achieved by
the method of internal standardization.
3.0 Definitions
3.1 The definitions are included in the text as needed.
4.0 Interferences [Reserved] 5.0 Safety
5.1 This method may involve hazardous materials, operations, and
equipment. This method does not purport to address all of the
safety problems associated with its use. It is the responsibility
of the user of this method to establish appropriate safety and
health practices and determine the applicability of regulatory
limitations prior to use.
6.0 Equipment and Supplies
6.1 Analytical balance, 160 g capacity, and 0.1 mg
resolution
6.2 Bottles, 2-oz capacity, with poly-cap screw lids
6.3 Mechanical shaker
6.4 Syringe, 10-ul capacity
6.5 Gas chromatograph, Hewlett Packard model 5890A, or
equivalent, configured with FID with a megabore jet, splitless
injector packed with silanized glass wool.
6.5.1 Establish the following gas chromatographic conditions,
and allow the system to thoroughly equilibrate before use.
Injection technique = Splitless Injector temperature = 225 deg C
Oven temperature = 70 deg C (isothermal) Detector: temperature =
300 deg C range = 5 attenuation = 0 Carrier gas: helium = 47 ml/min
Detector gases: hydrogen = 30 ml/min air = 270 ml/min make-up = 0
ml/min Analysis time: = 3.2 min at the specified carrier gas flow
rate and column temperature.
6.6 Gas chromatographic column, DB-1, 30 M X 0.53 ID, or
equivalent, with a 1.5 micron film thickness.
6.7 Data collection system, Perkin-Elmer/Nelson Series
Turbochrom 4 Series 900 Interface, or equivalent.
6.8 Pipet, automatic dispensing, 50-ml capacity, and 2-liter
reservoir.
6.9 Flasks, volumetric, class A, 100-ml and 1000-ml
capacity.
6.10 Pipet, volumetric delivery, 10-ml capacity, class A.
7.0 Chemicals and Reagents
CHEMICALS:
7.1 Styrene, C8H8, 99 + %, CAS 100-42-5 7.2 Alpha methyl styrene,
C9H10, 99%, CAS 98-83-9 7.3 Ethyl alcohol, C2H5OH, denatured
formula 2B, CAS 64-17-5
REAGENTS:
7.4 Internal Standard Stock Solution: 5.0 mg/ml AMS in ethyl
alcohol.
7.4.1 Into a 100-ml volumetric flask, weigh 0.50 g of AMS to the
nearest 0.1 mg.
7.4.2 Dilute to the mark with ethyl alcohol. This solution will
contain 5.0 mg/ml AMS in ethyl alcohol and will be labeled the AMS
STOCK SOLUTION.
7.5 Internal Standard Working Solution: 2500 ug/50 ml of AMS in
ethyl alcohol.
7.5.1 Using a 10 ml volumetric pipet, quantitatively transfer
10.0 ml of the AMS STOCK SOLUTION into a 1000-ml volumetric
flask.
7.5.2 Dilute to the mark with ethyl alcohol. This solution will
contain 2500 ug/50ml of AMS in ethyl alcohol and will be labeled
the AMS WORKING SOLUTION.
7.5.3 Transfer the AMS WORKING SOLUTION to the automatic
dispensing pipet reservoir.
7.6 Styrene Stock Solution: 5.0 mg/ml styrene in ethyl
alcohol.
7.6.1 Into a 100-ml volumetric flask, weigh 0.50 g of styrene to
the nearest 0.1 mg.
7.6.2 Dilute to the mark with ethyl alcohol. This solution will
contain 5.0 mg/ml styrene in ethyl alcohol and will be labeled the
STYRENE STOCK SOLUTION.
7.7 Styrene Working Solution: 5000 ug/10 ml of styrene in ethyl
alcohol.
7.7.1 Using a 10-ml volumetric pipet, quantitatively transfer
10.0 ml of the STYRENE STOCK SOLUTION into a 100-ml volumetric
flask.
7.7.2 Dilute to the mark with ethyl alcohol. This solution will
contain 5000 ug/10 ml of styrene in ethyl alcohol and will be
labeled the STYRENE WORKING SOLUTION.
8.0 Sample Collection, Preservation and Storage
8.1 Label a 2-oz sample poly-cap lid with the identity, date and
time of the sample to be obtained.
8.2 At the sample location, open sample valve for at least 15
seconds to ensure that the sampling pipe has been properly flushed
with fresh sample.
8.3 Fill the sample jar to the top (no headspace) with sample,
then cap it tightly.
8.4 Deliver sample to the Laboratory for testing within one hour
of sampling.
8.5 Laboratory testing will be done within two hours of the
sampling time.
8.6 No special storage conditions are required unless the
storage time exceeds 2 hours in which case refrigeration of the
sample is recommended.
9.0 Quality Control
9.1 For each sample type, 12 samples of SBR latex shall be
obtained from the process for the recovery study. Half the vials
and caps shall be tared, labeled “spiked”, and numbered 1 through
6. The other vials are labeled “unspiked” and need not be tared,
but are also numbered 1 through 6.
9.2 The six vials labeled “spiked” shall be spiked with an
amount of styrene to approximate 50% of the solution's expected
residual styrene level.
9.3 The spiked samples shall be shaken for several hours and
allowed to cool to room temperature before analysis.
9.4 The six samples of unspiked solution shall be coagulated and
a mean styrene value shall be determined, along with the standard
deviation, and the percent relative standard deviation.
9.5 The six samples of the spiked solution shall be coagulated
and the results of the analyses shall be determined using the
following equations:
Mr = Ms−Mu R = Mr/S where: Mu = Mean value of styrene in the
unspiked sample Ms = Measured amount of styrene in the spiked
sample Mr = Measured amount of the spiked compound S = Amount of
styrene added to the spiked sample R = Fraction of spiked styrene
recovered
9.6 A value of R between 0.70 and 1.30 is acceptable.
9.7 R is used to correct all reported results for each compound
by dividing the measured results of each compound by the R for that
compound for the same sample type.
10.0 Calibration
10.1 Using a 10-ml volumetric pipet, quantitatively transfer
10.0 ml of the STYRENE WORKING SOLUTION (section 7.7.2 of this
method) into a 2-oz bottle.
10.2 Using the AMS WORKING SOLUTION equipped with the automatic
dispensing pipet (section 7.5.3 of this method), transfer 50.0 ml
of the internal standard solution into the 2-oz bottle.
10.3 Cap the 2-oz bottle and swirl. This is the calibration
standard, which contains 5000 µg of styrene and 2500 µg of AMS.
10.4 Using the conditions prescribed (section 6.5 of this
method), chromatograph 1 µl of the calibration standard.
10.5 Obtain the peak areas and calculate the relative response
factor as described in the calculations section (section 12.1 of
this method).
11.0 Procedure
11.1 Into a tared 2-oz bottle, weigh 10.0 g of latex to the
nearest 0.1 g.
11.2 Using the AMS WORKING SOLUTION equipped with the automatic
dispensing pipet (section 7.5.3 of this method), transfer 50.0 ml
of the internal standard solution into the 2-oz bottle.
11.3 Cap the bottle. Using a mechanical shaker, shake the bottle
for at least one minute or until coagulation of the latex is
complete as indicated by a clear solvent.
11.4 Using the conditions prescribed (section 6.5 of this
method), chromatograph 1 ul of the liquor.
11.5 Obtain the peak areas and calculate the concentration of
styrene in the latex as described in the calculations section
(Section 12.2 of this method).
12.0 Calculations
12.1 Calibration:
RF = (Wx × Ais) / (Wis × Ax) where: RF = the relative response
factor for styrene Wx = the weight (ug) of styrene Ais = the area
of AMS Wis = the weight (ug) of AMS Ax = the area of styrene 12.2
Procedure: ppmstyrene = (Ax RF × Wis) / (Ais × Ws) where:
ppmstyrene = parts per million of styrene in the latex Ax = the
area of styrene RF = the response factor for styrene Wis = the
weight (ug) of AMS Ais = the area of AMS Ws = the weight (g) of the
latex sample 12.3 Correct for recovery (R) as determined by section
9.0 of this method. 13.0 Precision
13.1 Precision for the method was determined at the 80, 144,
590, and 1160 ppm levels. The standard deviations were 0.8, 1.5, 5
and 9 ppm respectively. The percent relative standard deviations
(%RSD) were 1% or less at all levels. Five degrees of freedom were
used for all precision data except at the 80 ppm level, where nine
degrees of freedom were used. Note: These are example results and
do not replace quality assurance procedures in this method.
14.0 Pollution Prevention
14.1 Waste generation should be minimized where possible. Sample
size should be an amount necessary to adequately run the
analysis.
15.0 Waste Management
15.1 Discard liquid chemical waste into the chemical waste
drum.
15.2 Discard latex sample waste into the latex waste drum.
15.3 Discard polymer waste into the polymer waste container.
16.0 References
16.1 This method is based on Goodyear Chemical Division Test
Method E-889.
Method 312C - Determination of Residual Styrene in SBR Latex
Produced by Emulsion Polymerization 1.0 Scope
1.1 This method is applicable for determining the amount of
residual styrene in SBR latex as produced in the emulsion
polymerization process.
2.0 Principle of Method
2.1 A weighed sample of latex is coagulated in 2-propanol which
contains alpha-methyl styrene as an Internal Standard. The extract
from the coagulation will contain the alpha-methyl styrene as the
Internal Standard and the residual styrene from the latex. The
extract is analyzed by a Gas Chromatograph. Percent styrene is
calculated by relating the area of the styrene peak to the area of
the Internal Standard peak of known concentration.
3.0 Definitions
3.1 The definitions are included in the text as needed.
4.0 Interferences [Reserved] 5.0 Safety
5.1 When using solvents, avoid contact with skin and eyes. Wear
hand and eye protection. Wash thoroughly after use.
5.2 Avoid overexposure to solvent vapors. Handle only in well
ventilated areas.
6.0 Equipment and Supplies
6.1 Gas Chromatograph - Hewlett Packard 5890, Series II
with flame ionization detector, or equivalent.
Column - HP 19095F-123, 30m × 0.53mm, or equivalent.
Substrate HP FFAP (cross-linked) film thickness 1 micrometer. Glass
injector port liners with silanized glass wool plug.
Integrator - HP 3396, Series II, or equivalent.
6.2 Wrist action shaker
6.3 Automatic dispenser
6.4 Automatic pipet, calibrated to deliver 5.0 ±0.01 grams of
latex
6.5 Four-ounce wide-mouth bottles with foil lined lids
6.6 Crimp cap vials, 2ml, teflon lined septa
6.7 Disposable pipets
6.8 Qualitative filter paper
6.9 Cap crimper
6.10 Analytical balance
6.11 10ml pipette
6.12 Two-inch funnel
7.0 Reagents and Standards
7.1 2-Propanol (HP2C grade)
7.2 Alpha methyl styrene (99 + % purity)
7.3 Styrene (99 + % purity)
7.4 Zero air
7.5 Hydrogen (chromatographic grade)
7.6 Helium
7.7 Internal Standard preparation
7.7.1 Weigh 5.000-5.005 grams of alpha-methyl styrene into a
100ml volumetric flask and bring to mark with 2-propanol to make
Stock “A” Solution.
Note:
Shelf life - 6 months.
7.7.2 Pipette 10ml of Stock “A” Solution into a 100ml volumetric
flask and bring to mark with 2-propanol to prepare Stock “B”
Solution.
7.7.3 Pipette 10ml of the Stock “B” solution to a 1000ml
volumetric flask and bring to the mark with 2-propanol. This will
be the Internal Standard Solution (0.00005 grams/ml).
7.8 Certification of Internal Standard - Each batch of Stock “B”
Solution will be certified to confirm concentration.
7.8.1 Prepare a Standard Styrene Control Solution in 2-propanol
by the following method:
7.8.1.1 Weigh 5.000 ±.005g of styrene to a 100ml volumetric
flask and fill to mark with 2-propanol to make Styrene Stock “A”
Solution.
7.8.1.2 Pipette 10ml of Styrene Stock “A” Solution to a 100ml
volumetric flask and fill to mark with 2-propanol to make Styrene
Stock “B” Solution.
7.8.1.3 Pipette 10ml of Styrene Stock “B” soluion to a 250ml
volumtric flask and fill to mark wtih 2-propanol to make the
Certification Solution.
7.8.2 Certify Alpha-Methyl Styrene Stock “B” Solution.
7.8.2.1 Pipette 5ml of the Certification Solution and 25ml of
the Alpha Methyl Styrene Internal Standard Solution to a 4-oz.
bottle, cap and shake well.
7.8.2.2 Analyze the resulting mixture by GC using the residual
styrene method. (11.4-11.6 of this method)
7.8.2.3 Calculate the weight of alpha methyl styrene present in
the 25ml aliquat of the new Alpha Methyl Styrene Standard by the
following equation:
Wx = Fx xWis(Ax/Ais) Where Ax = Peak area of alpha methyl styrene
Ais = Peak area of styrene Wx = Weight of alpha methyl styrene Wis
= Weight of styrene (.00100) Fx = Analyzed response factor = 1
The Alpha Methyl Styrene Stock Solution used to prepare the
Internal Standard Solution may be considered certified if the
weight of alpha methyl styrene analyzed by this method is within
the range of .00121g to .00129g.
8.0 Sampling
8.1 Collect a latex sample in a capped container. Cap the bottle
and identify the sample as to location and time.
8.2 Deliver sample to Laboratory for testing within one
hour.
8.3 Laboratory will test within two hours.
8.4 No special storage conditions are required.
9.0 Quality Control
9.1 The laboratory is required to operate a formal quality
control program. This consists of an initial demonstration of the
capability of the method as well as ongoing analysis of standards,
blanks, and spiked samples to demonstrate continued
performance.
9.1.1 When the method is first set up, a calibration is run and
the recovery efficiency for each type of sample must be
determined.
9.1.2 If new types of samples are being analyzed, then recovery
efficiency for each new type of sample must be determined. New type
includes any change, such as polymer type, physical form or a
significant change in the composition of the matrix.
9.2 Recovery efficiency must be determined once for each sample
type and whenever modifications are made to the method.
9.2.1 In determining the recovery efficiency, the quadruplet
sampling system shall be used. Six sets of samples (for a total of
24) shall be taken. In each quadruplet set, half of the samples
(two out of the four) shall be spiked with styrene.
9.2.2 Prepare the samples as described in section 8 of this
method. To the vials labeled “spiked”, add a known amount of
styrene that is expected to be present in the latex.
9.2.3 Run the spiked and unspiked samples in the normal manner.
Record the concentrations of styrene reported for each pair of
spiked and unspiked samples with the same vial number.
9.2.4 For each hydrocarbon, calculate the average recovery
efficiency (R) using the following equation:
R=Σ(Rn)/12 Where: n = sample number Rn = (Ms−Mu)/S Ms = total mass
of compound (styrene) measured in spiked sample (µg) Mu = total
mass of compound (styrene) measured in unspiked sample (µg) S =
theoretical mass of compound (styrene) spiked into sample (µg) R =
fraction of spiked compound (styrene) recovered
9.2.5 A different R value should be obtained for each sample
type. A value of R between 0.70 and 1.30 is acceptable.
9.2.6 R is used to correct all reported results for each
compound by dividing the measured results of each compound by the R
for that compound for the same sample type.
10.0 Calibration
A styrene control sample will be tested weekly to confirm the
FID response and calibration.
10.1 Using the Styrene Certification Solution prepared in 7.8.1,
perform test analysis as described in 7.8.2 using the equation in
7.8.2.3 to calculate results.
10.2 Calculate the weight of styrene in the styrene control
sample using the following equation:
Wsty = (Fx xAsty xWis)Ais
The instrument can be considered calibrated if the weight of the
styrene analyzed is within range of 0.00097-0.00103gms.
11.0 Procedure
11.1 Using an auto pipet, add 25ml of Internal Standard Solution
to a 4 oz. wide-mouth bottle.
11.2 Using a calibrated auto pipet, add 5.0 ±0.01g latex to the
bottle containing the 25ml of Internal Standard Solution.
11.3 Cap the bottle and place on the wrist action shaker. Shake
the sample for a minimum of five minutes using the timer on the
shaker. Remove from shaker.
11.4 Using a disposable pipet, fill the 2ml sample vial with the
clear alcohol extract. (If the extract is not clear, it should be
filtered using a funnel and filter paper.) Cap and seal the
vial.
11.5 Place the sample in the autosampler tray and start the GC
and Integrator. The sample will be injected into the GC by the
auto-injector, and the Integrator will print the results.
11.6 Gas Chromatograph Conditions
Oven Temp - 70 °C Injector Temp - 225 °C Detector Temp - 275 °C
Helium Pressure - 500 KPA Column Head Pressure - 70 KPA Makeup Gas
- 30 ml/min. Column - HP 19095F - 123, 30m × 0.53mm Substrate: HP -
FFAP (cross-linked) 1 micrometer film thickness 12.0 Calculations
12.1 The integrator is programmed to do the following
calculation at the end of the analysis:
%ResidualStyrene = (Ax XWis)/(Ais XWx)XFx X100 Where: Ax = Peak
area of styrene Ais = Peak area of internal standard Wx = Weight of
sample = 5g Wis = Weight of internal std. = 0.00125g Fx = Analyzed
response factor = 1.0
12.2 The response factor is determined by analyzing a solution
of 0.02g of styrene and 0.02g of alpha methyl styrene in 100ml of
2-propanol. Calculate the factor by the following equation:
Fx = (Wx xAis)/(Wis xAx) Where: Wx = Weight of styrene Ax = Peak
area of styrene Wis = Weight of alpha methyl styrene Ais = Peak
area of alpha methyl styrene 13.0 Method Performance
13.1 Performance must be determined for each sample type by
following the procedures in section 9 of this method.
14.0 Waste Generation
14.1 Waste generation should be minimized where possible.
15.0 Waste Management
15.1 All waste shall be handled in accordance with Federal and
State environmental regulations.
16.0 References [Reserved] Method 313A - Determination of Residual
Hydrocarbons in Rubber Crumb 1.0 Scope and Application
1.1 This method determines residual toluene and styrene in
stripper crumb of the of the following types of rubber:
polybutadiene (PBR) and styrene/butadiene rubber (SBR), both
derived from solution polymerization processes that utilize toluene
as the polymerization solvent.
1.2 The method is applicable to a wide range of concentrations
of toluene and styrene provided that calibration standards cover
the desired range. It is applicable at least over the range of 0.01
to 10.0 % residual toluene and from 0.1 to 3.0 % residual styrene.
It is probably applicable over a wider range, but this must be
verified prior to use.
1.3 The method may also be applicable to other process samples
as long as they are of a similar composition to stripper crumb. See
section 3.1 of this method for a description of stripper crumb.
2.0 Summary of Method
2.1 The wet crumb is placed in a sealed vial and run on a
headspace sampler which heats the vial to a specified temperature
for a specific time and then injects a known volume of vapor into a
capillary GC. The concentration of each component in the vapor is
proportional to the level of that component in the crumb sample and
does not depend on water content of the crumb.
2.2 Identification of each component is performed by comparing
the retention times to those of known standards.
2.3 Results are calculated by the external standard method since
injections are all performed in an identical manner. The response
for each component is compared with that obtained from dosed
samples of crumb.
2.4 Measured results of each compound are corrected by dividing
each by the average recovery efficiency determined for the same
compound in the same sample type.
3.0 Definitions
3.1 Stripper crumb refers to pieces of rubber resulting from the
steam stripping of a toluene solution of the same polymer in a
water slurry. The primary component of this will be polymer with
lesser amounts of entrained water and residual toluene and other
hydrocarbons. The amounts of hydrocarbons present must be such that
the crumb is a solid material, generally less that 10 % of the dry
rubber weight.
4.0 Interferences
4.1 Contamination is not normally a problem since samples are
sealed into vials immediately on sampling.
4.2 Cross contamination in the headspace sampler should not be a
problem if the correct sampler settings are used. This should be
verified by running a blank sample immediately following a normal
or high sample. Settings may be modified if necessary if this
proves to be a problem, or a blank sample may be inserted between
samples.
4.3 Interferences may occur if volatile hydrocarbons are present
which have retention times close to that of the components of
interest. Since the solvent makeup of the processes involved are
normally fairly well defined this should not be a problem. If it is
found to be the case, switching to a different chromatographic
column will probably resolve the situation.
5.0 Safety
5.1 The chemicals specified in this method should all be handled
according to standard laboratory practices as well as any special
precautions that may be listed in the MSDS for that compound.
5.2 Sampling of strippers or other process streams may involve
high pressures and temperatures or may have the potential for
exposure to chemical fumes. Only personnel who have been trained in
the specific sampling procedures required for that process should
perform this operation. An understanding of the process involved is
necessary. Proper personal protective equipment should be worn. Any
sampling devices should be inspected prior to use. A detailed
sampling procedure which specifies exactly how to obtain the sample
must be written and followed.
6.0 Equipment and Supplies
6.1 Hewlett Packard (HP) 7694 Headspace sampler, or equivalent,
with the following conditions:
Times (min.): GC cycle time 6.0 , vial equilibration 30.0 ,
pressurization 0.25 , loop fill 0.25, loop equilibration 0.05 ,
inject 0.25 Temperatures (deg C): oven 70, loop 80, transfer line
90 Pressurization gas: He @ 16 psi
6.2 HP 5890 Series II capillary gas chromatograph, or
equivalent, with the following conditions:
Column: Supelco SPB-1, or equivalent, 15m × .25mm × .25 µ film
Carrier: He @ 6 psi Run time: 4 minutes Oven: 70 deg C isothermal
Injector: 200 deg C split ratio 50:1 Detector: FID @ 220 deg C
6.3 HP Chemstation consisting of computer, printer and
Chemstation software, or an equivalent chromatographic data
system.
6.4 20 ml headspace vials with caps and septa.
6.5 Headspace vial crimper.
6.6 Microliter pipetting syringes.
6.7 Drying oven at 100 deg C vented into cold trap or other
means of trapping hydrocarbons released.
6.8 Laboratory shaker or tumbler suitable for the headspace
vials.
6.9 Personal protective equipment required for sampling the
process such as rubber gloves and face and eye protection.
7.0 Reagents and Standards
7.1 Toluene, 99.9 + % purity, HPLC grade.
7.2 Styrene, 99.9 + % purity, HPLC grade.
7.3 Dry rubber of same type as the stripper crumb samples.
8.0 Sample Collection, Preservation and Storage
8.1 Collect a sample of crumb in a manner appropriate for the
process equipment being sampled.
8.1.1 If conditions permit, this may be done by passing a stream
of the crumb slurry through a strainer, thus separating the crumb
from the water. Allow the water to drain freely, do not attempt to
squeeze any water from the crumb. Results will not depend on the
exact water content of the samples. Immediately place several
pieces of crumb directly into a headspace vial. This should be done
with rubber gloves to protect the hands from both the heat and from
contact with residual hydrocarbons. The vial should be between 1/4
and 1/3 full. Results do not depend on sample size as long as there
is sufficient sample to reach an equilibrium vapor pressure in the
headspace of the vial. Cap and seal the vial. Prepare each sample
at least in duplicate. This is to minimize the effect of the
variation that naturally occurs in the composition of non
homogeneous crumb. The free water is not analyzed by this method
and should be disposed of appropriately along with any unused
rubber crumb.
8.1.2 Alternatively the process can be sampled in a specially
constructed sealed bomb which can then be transported to the
laboratory. The bomb is then cooled to ambient temperature by
applying a stream of running water. The bomb can then be opened and
the crumb separated from the water and the vials filled as
described in section 8.1.1 of this method. The bomb may be stored
up to 8 hours prior to transferring the crumb into vials.
8.2 The sealed headspace vials may be run immediately or may be
stored up to 72 hours prior to running. It is possible that even
longer storage times may be acceptable, but this must be verified
for the particular type of sample being analyzed (see section 9.2.3
of this method). The main concern here is that some types of rubber
eventually may flow, thus compacting the crumb so that the surface
area is reduced. This may have some effect on the headspace
equilibration.
9.0 Quality Control
9.1 The laboratory is required to operate a formal quality
control program. This consists of an initial demonstration of the
capability of the method as well as ongoing analysis of standards,
blanks and spiked samples to demonstrate continued performance.
9.1.1 When the method is first set up a calibration is run
(described in section 10 of this method) and an initial
demonstration of method capability is performed (described in
section 9.2 of this method). Also recovery efficiency for each type
of sample must be determined (see section 9.4 of this method).
9.1.2 It is permissible to modify this method in order to
improve separations or make other improvements, provided that all
performance specifications are met. Each time a modification to the
method is made it is necessary to repeat the calibration (section
10 of this method), the demonstration of method performance
(section 9.2 of this method) and the recovery efficiency for each
type of sample (section 9.4 of this method).
9.1.3 Ongoing performance should be monitored by running a
spiked rubber standard. If this test fails to demonstrate that the
analysis is in control, then corrective action must be taken. This
method is described in section 9.3 of this method.
9.1.4 If new types of samples are being analyzed then recovery
efficiency for each new type of sample must be determined. New type
includes any change, such as polymer type, physical form or a
significant change in the composition of the matrix.
9.2 Initial demonstration of method capability to establish the
accuracy and precision of the method. This is to be run following
the calibration described in section 10 of this method.
9.2.1 Prepare a series of identical spiked rubber standards as
described in section 9.3 of this method. A sufficient number to
determine statistical information on the test should be run. Ten
may be a suitable number, depending on the quality control
methodology used at the laboratory running the tests. These are run
in the same manner as unknown samples (see section 11 of this
method).
9.2.2 Determine mean and standard deviation for the results. Use
these to determine the capability of the method and to calculate
suitable control limits for the ongoing performance check which
will utilize the same standards.
9.2.3 Prepare several additional spiked rubber standards and run
2 each day to determine the suitability of storage of the samples
for 24, 48 and 72 hours or longer if longer storage times are
desired.
9.3 A spiked rubber standard should be run on a regular basis to
verify system performance. This would probably be done daily if
samples are run daily. This is prepared in the same manner as the
calibration standards (section 10.1 of this method), except that
only one concentration of toluene and styrene is prepared. Choose
concentrations of toluene and styrene that fall in the middle of
the range expected in the stripper crumb and then do not change
these unless there is a major change in the composition of the
unknowns. If it becomes necessary to change the composition of this
standard the initial performance demonstration must be repeated
with the new standard (section 9.2 of this method).
9.3.1 Each day prepare one spiked rubber standard to be run the
following day. The dry rubber may be prepared in bulk and stored
for any length of time consistent with the shelf life of the
product. The addition of water and hydrocarbons must be performed
daily and all the steps described under section 10.1 of this method
must be followed.
9.3.2 Run the spiked rubber standard prepared the previous day.
Record the results and plot on an appropriate control chart or
other means of determining statistical control.
9.3.3 If the results for the standard indicate that the test is
out of control then corrective action must be taken. This may
include a check on procedures, instrument settings, maintenance or
recalibration. Samples may be stored (see section 8.2 of this
method) until compliance is demonstrated.
9.4 Recovery efficiency must be determined once for each sample
type and whenever modifications are made to the method.
9.4.1 For each sample type collect 12 samples from the process
(section 8.1 of this method). This should be done when the process
is operating in a normal manner and residual hydrocarbon levels are
in the normal range. Half the vials and caps should be tared,
labeled “spiked” and numbered 1 through 6. The other vials are
labeled “unspiked” and need not be tared but are also numbered 1
through 6. Immediately on sampling, the vials should be capped to
prevent loss of volatiles. Allow all the samples to cool completely
to ambient temperature. Reweigh each of the vials labeled “spiked”
to determine the weight of wet crumb inside.
9.4.2 The dry weight of rubber present in the wet crumb is
estimated by multiplying the weight of wet crumb by the fraction of
nonvolatiles typical for the sample. If this is not known, an
additional quantity of crumb may be sampled, weighed, dried in an
oven and reweighed to determine the fraction of volatiles and
nonvolatiles prior to starting this procedure.
9.4.3 To the vials labeled “spiked” add an amount of a mixture
of toluene and styrene that is between 40 and 60 % of the amount
expected in the crumb. This is done by removing the cap, adding the
mixture by syringe, touching the tip of the needle to the sample in
order to remove the drop and then immediately recapping the vials.
The mixture is not added through the septum, because a punctured
septum may leak and vent vapors as the vial is heated. The weights
of toluene and styrene added may be calculated from the volumes of
the mixture added, its composition and density, or may be
determined by the weight of the vials and caps prior to and after
addition. The exact dry weight of rubber present and the
concentration of residual toluene and styrene are not known at this
time so an exact calculation of the concentration of hydrocarbons
is not possible until the test is completed.
9.4.4 Place all the vials onto a shaker or tumbler for 24 ±2
hours. This is essential in order for the hydrocarbons to be evenly
distributed and completely absorbed into the rubber. If this is not
followed the toluene and styrene will be mostly at the surface of
the rubber and high results will be obtained.
9.4.5 Remove the vials from the shaker and tap them so that all
the crumb settles to the bottom of the vials. Allow them to stand
for 1 hour prior to analysis to allow any liquid to drain fully to
the bottom.
9.4.6 Run the spiked and unspiked samples in the normal manner.
Record the concentrations of toluene and styrene reported for each
pair of spiked and unspiked samples with the same vial number.
9.4.7 Open each of the vials labeled “spiked”, remove all the
rubber crumb and place it into a tarred drying pan. Place in a 100
deg C oven for two hours, cool and reweigh. Subtract the weight of
the tare to give the dry weight of rubber in each spiked vial.
Calculate the concentration of toluene and styrene spiked into each
vial as percent of dry rubber weight. This will be slightly
different for each vial since the weights of dry rubber will be
different.
9.4.8 For each hydrocarbon calculate the average recovery
efficiency (R) using the following equations:
R = R_Σ(Pn)/6 (average of the 6 individual Rn values) Where: Rn =
(Cns - Cnu) / Sn Where: n = vial number Cns = concentration of
compound measured in spiked sample number n. Cnu = concentration of
compound measured in unspiked sample number n. Sn = theoretical
concentration of compound spiked into sample n calculated in step
9.4.7
9.4.9 A different R value should be obtained for each compound
(styrene and toluene) and for each sample type.
9.4.10 A value of R between 0.70 and 1.30 is acceptable.
9.4.11 R is used to correct all reported results for each
compound by dividing the measured results of each compound by the R
for that compound for the same sample type (see section 12.2 of
this method.)
10.0 Calibration
10.1 Calibration standards are prepared by dosing known amounts
of the hydrocarbons of interest into vials containing known amounts
of rubber and water.
10.1.1 Cut a sufficient quantity of dry rubber of the same type
as will be analyzed into pieces about the same size as that of the
crumb. Place these in a single layer on a piece of aluminum foil or
other suitable surface and place into a forced air oven at 100 °C
for four hours. This is to remove any residual hydrocarbons that
may be present. This step may be performed in advance.
10.1.2 Into each of a series of vials add 3.0 g of the dry
rubber.
10.1.3 Into each vial add 1.0 ml distilled water or an amount
that is close to the amount that will be present in the unknowns.
The exact amount of water present does not have much effect on the
analysis, but it is necessary to have a saturated environment. The
water will also aid in the uniform distribution of the spiked
hydrocarbons over the surface of the rubber after the vials are
placed on the shaker (in step 10.1.5 of this method).
10.1.4 Into each vial add varying amounts of toluene and styrene
by microliter syringe and cap the vials immediately to prevent
loss. The tip of the needle should be carefully touched to the
rubber in order to transfer the last drop to the rubber. Toluene
and styrene may first be mixed together in suitable proportions and
added together if desired. The weights of toluene and styrene added
may be calculated from the volumes of the mixture added, its
composition and density, or may be determined by the weight of the
vials and caps prior to and after addition. Concentrations of added
hydrocarbons are calculated as percent of the dry rubber weight. At
least 5 standards should be prepared with the amounts of
hydrocarbons added being calculated to cover the entire range
possible in the unknowns. Retain two samples with no added
hydrocarbons as blanks.
10.1.5 Place all the vials onto a shaker or tumbler for 24 ±2
hours. This is essential in order for the hydrocarbons to be evenly
distributed and completely absorbed into the rubber. If this is not
followed the toluene and styrene will be mostly at the surface of
the rubber and high results will be obtained.
10.1.6 Remove the vials from the shaker and tap them so that all
the crumb settles to the bottom of the vials. Allow them to stand
for 1 hour prior to analysis to allow any liquid to drain fully to
the bottom.
10.2 Run the standards and blanks in the same manner as
described for unknowns (section 11 of this method), starting with a
blank, then in order of increasing hydrocarbon content and ending
with the other blank.
10.3 Verify that the blanks are sufficiently free from toluene
and styrene or any interfering hydrocarbons.
10.3.1 It is possible that trace levels may be present even in
dry product. If levels are high enough that they will interfere
with the calibration then the drying procedure in section 10.1.1 of
this method should be reviewed and modified as needed to ensure
that suitable standards can be prepared.
10.3.2 It is possible that the final blank is contaminated by
the previous standard. If this is the case review and modify the
sampler parameters as needed to eliminate this problem. If
necessary it is possible to run blank samples between regular
samples in order to reduce this problem, though it should not be
necessary if the sampler is properly set up.
10.4 Enter the amounts of toluene and styrene added to each of
the samples (as calculated in section 10.1.4 of this method) into
the calibration table and perform a calibration utilizing the
external standard method of analysis.
10.5 At low concentrations the calibration should be close to
linear. If a wide range of levels are to be determined it may be
desirable to apply a nonlinear calibration to get the best fit.
11.0 Procedure
11.1 Place the vials in the tray of the headspace sampler. Enter
the starting and ending positions through the console of the
sampler. For unknown samples each is run in duplicate to minimize
the effect of variations in crumb composition. If excessive
variation is noted it may be desirable to run more than two of each
sample.
11.2 Make sure the correct method is loaded on the Chemstation.
Turn on the gas flows and light the FID flame.
11.3 Start the sequence on the Chemstation. Press the START
button on the headspace unit. The samples will be automatically
injected after equilibrating for 30 minutes in the oven. As each
sample is completed the Chemstation will calculate and print out
the results as percent toluene and styrene in the crumb based on
the dry weight of rubber.
12.0 Data Analysis and Calculations
12.1 For each set of duplicate samples calculate the average of
the measured concentration of toluene and styrene. If more than two
replicates of each sample are run calculate the average over all
replicates.
12.2 For each sample correct the measured amounts of toluene and
styrene using the following equation:
Corrected Result = Cm/R Where: Cm = Average measured concentration
for that compound. R = Recovery efficiency for that compound in the
same sample type (see section 9.4 of this method)
12.3 Report the recovery efficiency (R) and the corrected
results of toluene and styrene for each sample.
13.0 Method Performance
13.1 This method can be very sensitive and reproducible. The
actual performance depends largely on the exact nature of the
samples being analyzed. Actual performance must be determined by
each laboratory for each sample type.
13.2 The main source of variation is the actual variation in the
composition of non homogeneous crumb in a stripping system and the
small sample sizes employed here. It therefore is the
responsibility of each laboratory to determine the optimum number
of replicates of each sample required to obtain accurate
results.
14.0 Pollution Prevention
14.1 Samples should be kept sealed when possible in order to
prevent evaporation of hydrocarbons.
14.2 When drying of samples is required it should be done in an
oven which vents into a suitable device that can trap the
hydrocarbons released.
14.3 Dispose of samples as described in section 15.
15.0 Waste Management
15.1 Excess stripper crumb and water as well as the contents of
the used sample vials should be properly disposed of in accordance
with local and federal regulations.
15.2 Preferably this will be accomplished by having a system of
returning unused and spent samples to the process.
16.0 References
16.1 “HP 7694 Headspace Sampler - Operating and Service Manual”,
Hewlett-Packard Company, publication number G1290-90310, June
1993.
Method 313B - The Determination of Residual Hydrocarbon in Solution
Polymers by Capillary Gas Chromatography 1.0 Scope
1.1 This method is applicable to solution polymerized
polybutadiene (PBD).
1.2 This method quantitatively determines n-hexane in wet crumb
polymer at levels from 0.08 to 0.15% by weight.
1.3 This method may be extended to the determination of other
hydrocarbons in solution produced polymers with proper
experimentation and documentation.
2.0 Principle of Method
2.1 A weighed sample of polymer is dissolved in chloroform and
the cement is coagulated with an isopropyl alcohol solution
containing a specific amount of alpha-methyl styrene (AMS) as the
internal standard. The extract of this coagulation is then injected
into a gas chromatograph and separated into individual components.
Quantification is achieved by the method of internal
standardization.
3.0 Definitions
3.1 The definitions are included in the text as needed.
4.0 Interferences [Reserved] 5.0 Safety
5.1 This method may involve hazardous materials, operations, and
equipment. This method does not purport to address all of the
safety problems associated with its use. It is the responsibility
of the user of this method to establish appropriate safety and
health practices and determine the applicability of regulatory
limitations prior to use.
6.0 Equipment and Supplies
6.1 Analytical balance, 160 g capacity, 0.1 mg resolution
6.2 Bottles, 2-oz capacity with poly-cap screw lids
6.3 Mechanical shaker
6.4 Syringe, 10-ul capacity
6.5 Syringe, 2.5-ml capacity, with 22 gauge 1.25 inch needle,
PP/PE material, disposable
6.6 Gas chromatograph, Hewlett-Packard model 5890, or
equivalent, configured with FID, split injector packed with
silanized glass wool.
6.6.1 Establish the following gas chromatographic conditions,
and allow the system to thoroughly equilibrate before use.
6.6.2 Injector parameters:
Injection technique = Split Injector split flow = 86 ml/min
Injector temperature = 225 deg C
6.6.3 Oven temperature program:
Initial temperature = 40 deg C Initial time = 6 min Program rate =
10 deg C/min Upper limit temperature = 175 deg C Upper limit
interval = 10 min
6.6.4 Detector parameters:
Detector temperature = 300 deg C Hydrogen flow = 30 ml/min Air flow
= 350 ml/min Nitrogen make up = 26 ml/min
6.7 Gas chromatographic columns: SE-54 (5%-phenyl)
(1%-vinyl)-methylpolysiloxane, 15 M × 0.53 mm ID with a 1.2 micron
film thickness, and a Carbowax 20M (polyethylene glycol), 15 M ×
0.53 mm ID with a 1.2 micron film thickness.
6.7.1 Column assembly: using a 0.53 mm ID butt connector union,
join the 15 M × 0.53 mm SE-54 column to the 15 M × 0.53 mm Carbowax
20M. The SE-54 column will be inserted into the injector and the
Carbowax 20M inserted into the detector after they have been
joined.
6.7.2 Column parameters:
Helium flow = 2.8 ml/min Helium headpressure = 2 psig
6.8 Centrifuge
6.9 Data collection system, Hewlett-Packard Model 3396, or
equivalent
6.10 Pipet, 25-ml capacity, automatic dispensing, and 2 liter
reservoir
6.11 Pipet, 2-ml capacity, volumetric delivery, class A
6.12 Flasks, 100 and 1000-ml capacity, volumetric, class A
6.13 Vial, serum, 50-ml capacity, red rubber septa and crimp
ring seals
6.14 Sample collection basket fabricated out of wire mesh to
allow for drainage
7.0 Chemicals and Reagents
CHEMICALS:
7.1 alpha-Methyl Styrene, C9H10, 99 + % purity, CAS 98-83-9
7.2 n-Hexane, C6H14, 99 + % purity, CAS 110-54-3
7.3 Isopropyl alcohol, C3H8O 99.5 + % purity, reagent grade, CAS
67-63-0
7.4 Chloroform, CHCl3, 99% min., CAS 67-66-3
REAGENTS:
7.5 Internal Standard Stock Solution: 10 mg/25 ml AMS in
isopropyl alcohol.
7.5.1 Into a 25-ml beaker, weigh 0.4 g of AMS to the nearest 0.1
mg.
7.5.2 Quantitatively transfer this AMS into a 1-L volumetric
flask. Dilute to the mark with isopropyl alcohol.
7.5.3 Transfer this solution to the automatic dispensing pipet
reservoir. This will be labeled the AMS STOCK SOLUTION.
7.6 n-Hexane Stock Solution: 13mg/2ml hexane in isopropyl
alcohol.
7.6.1 Into a 100-ml volumetric flask, weigh 0.65 g of n-hexane
to the nearest 0.1 mg.
7.6.2 Dilute to the mark with isopropyl alcohol. This solution
will be labeled the n-HEXANE STOCK SOLUTION.
8.0 Sample Collection, Preservation and Storage
8.1 A sampling device similar to Figure 1 is used to collect a
non-vented crumb rubber sample at a location that is after the
stripping operation but before the sample is exposed to the
atmosphere.
8.2 The crumb rubber is allowed to cool before opening the
sampling device and removing the sample.
8.3 The sampling device is opened and the crumb rubber sample is
collected in the sampling basket.
8.4 One pound of crumb rubber sample is placed into a
polyethylene bag. The bag is labeled with the time, date and sample
location.
8.5 The sample should be delivered to the laboratory for testing
within one hour of sampling.
8.6 Laboratory testing will be done within 3 hours of the
sampling time.
8.7 No special storage conditions are required unless the
storage time exceeds 3 hours in which case refrigeration of the
samples is recommended.
9.0 Quality Control
9.1 For each sample type, 12 samples shall be obtained from the
process for the recovery study. Half of the vials and caps shall be
tared, labeled “spiked”, and numbered 1 through 6. The other vials
shall be labeled “unspiked” and need not be tared, but are also
numbered 1 through 6.
9.2 Determine the % moisture content of the crumb sample. After
determining the % moisture content, the correction factor for
calculating the dry crumb weight can be determined by using the
equation in section 12.2 of this method.
9.3 Run the spiked and unspiked samples in the normal manner.
Record the concentrations of the n-hexane content of the mixed
hexane reported for each pair of spiked and unspiked samples.
9.4 For the recovery study, each sample of crumb shall be
dissolved in chloroform containing a known amount of mixed hexane
solvent.
9.5 For each hydrocarbon, calculate the recovery efficiency (R)
using the following equations:
Mr = Ms−Mu R = Mr/S Where: Mu = Measured amount of compound in the
unspiked sample Ms = Measured amount of compound in the spiked
sample Mr = Measured amount of the spiked compound S = Amount of
compound added to the spiked sample R = Fraction of spiked compound
recovered
9.6 Normally a value of R between 0.70 and 1.30 is
acceptable.
9.7 R is used to correct all reported results for each compound
by dividing the measured results of each compound by the R for that
compound for the same sample type.
10.0 Calibration
10.1 Using the AMS STOCK SOLUTION equipped with the automatic
dispensing pipet (7.5.3 of this method), transfer 25.0 ml of the
internal standard solution into an uncapped 50-ml serum vial.
10.2 Using a 2.0 ml volumetric pipet, quantitatively transfer
2.0 ml of the n-HEXANE STOCK SOLUTION (7.6.2 of this method) into
the 50-ml serum vial and cap. This solution will be labeled the
CALIBRATION SOLUTION.
10.3 Using the conditions prescribed (6.6 of this method),
inject 1 µl of the supernate.
10.4 Obtain the peak areas and calculate the response factor as
described in the calculations section (12.1 of this method).
11.0 Procedure
11.1 Determination of Dry Polymer Weight
11.1.1 Remove wet crumb from the polyethylene bag and place on
paper towels to absorb excess surface moisture.
11.1.2 Cut small slices or cubes from the center of the crumb
sample to improve sample uniformity and further eliminate surface
moisture.
11.1.3 A suitable gravimetric measurement should be made on a
sample of this wet crumb to determine the correction factor needed
to calculate the dry polymer weight.
11.2 Determination of n-Hexane in Wet Crumb
11.2.1 Remove wet crumb from the polyethylene bag and place on
paper towels to absorb excess surface moisture.
11.2.2 Cut small slices or cubes from the center of the crumb
sample to improve sample uniformity and further eliminate surface
moisture.
11.2.3 Into a tared 2 oz bottle, weigh 1.5 g of wet polymer to
the nearest 0.1 mg.
11.2.4 Add 25 ml of chloroform to the 2 oz bottle and cap.
11.2.5 Using a mechanical shaker, shake the bottle until the
polymer dissolves.
11.2.6 Using the autodispensing pipet, add 25.0 ml of the AMS
STOCK SOLUTION (7.5.3 of this method) to the dissolved polymer
solution and cap.
11.2.7 Using a mechanical shaker, shake the bottle for 10
minutes to coagulate the dissolved polymer.
11.2.8 Centrifuge the sample for 3 minutes at 2000 rpm.
11.2.9 Using the conditions prescribed (6.6 of this method),
chromatograph 1 µl of the supernate.
11.2.10 Obtain the peak areas and calculate the concentration of
the component of interest as described in the calculations (12.2 of
this method).
12.0 Calculations
12.1 Calibration:
RFx = (Wx × Ais) / (Wis × Ax) Where: RFx = the relative response
factor for n-hexane Wx = the weight (g) of n-hexane in the
CALIBRATION SOLUTION Ais = the area of AMS Wis = the weight (g) of
AMS in the CALIBRATION SOLUTION Ax = the area of n-hexane
12.2 Procedure:
12.2.1 Correction Factor for calculating dry crumb weight.
F = 1 - (% moisture / 100) Where: F = Correction factor for
calculating dry crumb weight % moisture determined by appropriate
method
12.2.2 Moisture adjustment for chromatographic
determination.
Ws = F × Wc Where: Ws = the weight (g) of the dry polymer corrected
for moisture F = Correction factor for calculating dry crumb weight
Wc = the weight (g) of the wet crumb in section 9.6
12.2.3 Concentration (ppm) of hexane in the wet crumb.
ppmx = (Ax * RFx * Wis * 10000) / (Ais * Ws) Where: ppmx = parts
per million of n-hexane in the polymer Ax = the area of n-hexane
RFx = the relative response factor for n-hexane Wis = the weight
(g) of AMS in the sample solution Ais = the area of AMS Ws = the
weight (g) of the dry polymer corrected for moisture 13.0 Method
Performance
13.1 Precision for the method was determined at the 0.08%
level.
The standard deviation was 0.01 and the percent relative
standard deviation (RSD) was 16.3 % with five degrees of
freedom.
14.0 Waste Generation
14.1 Waste generation should be minimized where possible.
15.0 Waste Management
15.1 Discard liquid chemical waste into the chemical waste
drum.
15.2 Discard polymer waste into the polymer waste container.
16.0 References
16.1 This method is based on Goodyear Chemical Division Test
Method E-964.
Method 315 - Determination of Particulate and Methylene Chloride
Extractable Matter (MCEM) From Selected Sources at Primary Aluminum
Production Facilities Note:
This method does not include all of the specifications (e.g.,
equipment and supplies) and procedures (e.g., sampling and
analytical) essential to its performance. Some material is
incorporated by reference from other methods in this part.
Therefore, to obtain reliable results, persons using this method
should have a thorough knowledge of at least the following
additional test methods: Method 1, Method 2, Method 3, and Method 5
of 40 CFR part 60, appendix A.
1.0 Scope and Application
1.1 Analytes. Particulate matter (PM). No CAS number assigned.
Methylene chloride extractable matter (MCEM). No CAS number
assigned.
1.2 Applicability. This method is applicable for the
simultaneous determination of PM and MCEM when specified in an
applicable regulation. This method was developed by consensus with
the Aluminum Association and the U.S. Environmental Protection
Agency (EPA) and has limited precision estimates for MCEM; it
should have similar precision to Method 5 for PM in 40 CFR part 60,
appendix A since the procedures are similar for PM.
1.3 Data quality objectives. Adherence to the requirements of
this method will enhance the quality of the data obtained from air
pollutant sampling methods.
2.0 Summary of Method
Particulate matter and MCEM are withdrawn isokinetically from
the source. PM is collected on a glass fiber filter maintained at a
temperature in the range of 120 ±14 °C (248 ±25 °F) or such other
temperature as specified by an applicable subpart of the standards
or approved by the Administrator for a particular application. The
PM mass, which includes any material that condenses on the probe
and is subsequently removed in an acetone rinse or on the filter at
or above the filtration temperature, is determined gravimetrically
after removal of uncombined water. MCEM is then determined by
adding a methylene chloride rinse of the probe and filter holder,
extracting the condensable hydrocarbons collected in the impinger
water, adding an acetone rinse followed by a methylene chloride
rinse of the sampling train components after the filter and before
the silica gel impinger, and determining residue gravimetrically
after evaporating the solvents.
3.0 Definitions [Reserved] 4.0 Interferences [Reserved] 5.0 Safety
This method may involve hazardous materials, operations, and
equipment. This method does not purport to address all of the
safety problems associated with its use. It is the responsibility
of the user of this method to establish appropriate safety and
health practices and determine the applicability of regulatory
limitations prior to performing this test method.
6.0 Equipment and Supplies Note:
Mention of trade names or specific products does not constitute
endorsement by the EPA.
6.1 Sample collection. The following items are required for
sample collection:
6.1.1 Sampling train. A schematic of the sampling train used in
this method is shown in Figure 5-1, Method 5, 40 CFR part 60,
appendix A-3. Complete construction details are given in APTD-0581
(Reference 2 in section 17.0 of this method); commercial models of
this train are also available. For changes from APTD-0581 and for
allowable modifications of the train shown in Figure 5-1, Method 5,
40 CFR part 60, appendix A-3, see the following subsections.
Note:
The operating and maintenance procedures for the sampling train
are described in APTD-0576 (Reference 3 in section 17.0 of this
method). Since correct usage is important in obtaining valid
results, all users should read APTD-0576 and adopt the operating
and maintenance procedures outlined in it, unless otherwise
specified herein. Alternative mercury-free thermometers may be used
if the thermometers are, at a minimum, equivalent in terms of
performance or suitably effective for the specific temperature
measurement application. The use of grease for sealing sampling
train components is not recommended because many greases are
soluble in methylene chloride. The sampling train consists of the
following components:
6.1.1.1 Probe nozzle. Glass or glass lined with sharp, tapered
leading edge. The angle of taper shall be ≤30 °, and the taper
shall be on the outside to preserve a constant internal diameter.
The probe nozzle shall be of the button-hook or elbow design,
unless otherwise specified by the Administrator. Other materials of
construction may be used, subject to the approval of the
Administrator. A range of nozzle sizes suitable for isokinetic
sampling should be available. Typical nozzle sizes range from 0.32
to 1.27 cm ( 1/8 to 1/2 in.) inside diameter (ID) in increments of
0.16 cm ( 1/16 in.). Larger nozzle sizes are also available if
higher volume sampling trains are used. Each nozzle shall be
calibrated according to the procedures outlined in section 10.0 of
this method.
6.1.1.2 Probe liner. Borosilicate or quartz glass tubing with a
heating system capable of maintaining a probe gas temperature at
the exit end during sampling of 120 ±14 °C (248 ±25 °F), or such
other temperature as specified by an applicable subpart of the
standards or approved by the Administrator for a particular
application. Because the actual temperature at the outlet of the
probe is not usually monitored during sampling, probes constructed
according to APTD-0581 and using the calibration curves of
APTD-0576 (or calibrated according to the procedure outlined in
APTD-0576) will be considered acceptable. Either borosilicate or
quartz glass probe liners may be used for stack temperatures up to
about 480 °C (900 °F); quartz liners shall be used for temperatures
between 480 and 900 °C (900 and 1,650 °F). Both types of liners may
be used at higher temperatures than specified for short periods of
time, subject to the approval of the Administrator. The softening
temperature for borosilicate glass is 820 °C (1,500 °F) and for
quartz glass it is 1,500 °C (2,700 °F).
6.1.1.3 Pitot tube. Type S, as described in section 6.1 of
Method 2, 40 CFR part 60, appendix A, or other device approved by
the Administrator. The pitot tube shall be attached to the probe
(as shown in Figure 5-1 of Method 5, 40 CFR part 60, appendix A) to
allow constant monitoring of the stack gas velocity. The impact
(high pressure) opening plane of the pitot tube shall be even with
or above the nozzle entry plane (see Method 2, Figure 2-6b, 40 CFR
part 60, appendix A) during sampling. The Type S pitot tube
assembly shall have a known coefficient, determined as outlined in
section 10.0 of Method 2, 40 CFR part 60, appendix A.
6.1.1.4 Differential pressure gauge. Inclined manometer or
equivalent device (two), as described in section 6.2 of Method 2,
40 CFR part 60, appendix A. One manometer shall be used for
velocity head (Dp) readings, and the other, for orifice
differential pressure readings.
6.1.1.5 Filter holder. Borosilicate glass, with a glass frit
filter support and a silicone rubber gasket. The holder design
shall provide a positive seal against leakage from the outside or
around the filter. The holder shall be attached immediately at the
outlet of the probe (or cyclone, if used).
6.1.1.6 Filter heating system. Any heating system capable of
maintaining a temperature around the filter holder of 120 ±14 °C
(248 ±25 °F) during sampling, or such other temperature as
specified by an applicable subpart of the standards or approved by
the Administrator for a particular application. Alternatively, the
tester may opt to operate the equipment at a temperature lower than
that specified. A temperature gauge capable of measuring
temperature to within 3 °C (5.4 °F) shall be installed so that the
temperature around the filter holder can be regulated and monitored
during sampling. Heating systems other than the one shown in
APTD-0581 may be used.
6.1.1.7 Temperature sensor. A temperature sensor capable of
measuring temperature to within ±3 °C (5.4 °F) shall be installed
so that the sensing tip of the temperature sensor is in direct
contact with the sample gas, and the temperature around the filter
holder can be regulated and monitored during sampling.
6.1.1.8 Condenser. The following system shall be used to
determine the stack gas moisture content: four glass impingers
connected in series with leak-free ground glass fittings. The
first, third, and fourth impingers shall be of the Greenburg-Smith
design, modified by replacing the tip with a 1.3 cm (1/2 in.) ID
glass tube extending to about 1.3 cm (1/2 in.) from the bottom of
the flask. The second impinger shall be of the Greenburg-Smith
design with the standard tip. The first and second impingers shall
contain known quantities of water (section 8.3.1 of this method),
the third shall be empty, and the fourth shall contain a known
weight of silica gel or equivalent desiccant. A temperature sensor
capable of measuring temperature to within 1 °C (2 °F) shall be
placed at the outlet of the fourth impinger for monitoring.
6.1.1.9 Metering system. Vacuum gauge, leak-free pump,
temperature sensors capable of measuring temperature to within 3 °C
(5.4 °F), dry gas meter (DGM) capable of measuring volume to within
2 percent, and related equipment, as shown in Figure 5-1 of Method
5, 40 CFR part 60, appendix A. Other metering systems capable of
maintaining sampling rates within 10 percent of isokinetic and of
determining sample volumes to within 2 percent may be used, subject
to the approval of the Administrator. When the metering system is
used in conjunction with a pitot tube, the system shall allow
periodic checks of isokinetic rates.
6.1.1.10 Sampling trains using metering systems designed for
higher flow rates than that described in APTD-0581 or APTD-0576 may
be used provided that the specifications of this method are
met.
6.1.2 Barometer. Mercury, aneroid, or other barometer capable of
measuring atmospheric pressure to within 2.5 mm (0.1 in.) Hg.
Note:
The barometric reading may be obtained from a nearby National
Weather Service station. In this case, the station value (which is
the absolute barometric pressure) shall be requested and an
adjustment for elevation differences between the weather station
and sampling point shall be made at a rate of minus 2.5 mm (0.1 in)
Hg per 30 m (100 ft) elevation increase or plus 2.5 mm (0.1 in) Hg
per 30 m (100 ft) elevation decrease.
6.1.3 Gas density determination equipment. Temperature sensor
and pressure gauge, as described in sections 6.3 and 6.4 of Method
2, 40 CFR part 60, appendix A, and gas analyzer, if necessary, as
described in Method 3, 40 CFR part 60, appendix A. The temperature
sensor shall, preferably, be permanently attached to the pitot tube
or sampling probe in a fixed configuration, such that the tip of
the sensor extends beyond the leading edge of the probe sheath and
does not touch any metal. Alternatively, the sensor may be attached
just prior to use in the field. Note, however, that if the
temperature sensor is attached in the field, the sensor must be
placed in an interference-free arrangement with respect to the Type
S pitot tube openings (see Method 2, Figure 2-4, 40 CFR part 60,
appendix A). As a second alternative, if a difference of not more
than 1 percent in the average velocity measurement is to be
introduced, the temperature sensor need not be attached to the
probe or pitot tube. (This alternative is subject to the approval
of the Administrator.)
6.2 Sample recovery. The following items are required for sample
recovery:
6.2.1 Probe-liner and probe-nozzle brushes. Nylon or Teflon ®
bristle brushes with stainless steel wire handles. The probe brush
shall have extensions (at least as long as the probe) constructed
of stainless steel, nylon, Teflon ®, or similarly inert material.
The brushes shall be properly sized and shaped to brush out the
probe liner and nozzle.
6.2.2 Wash bottles. Glass wash bottles are recommended.
Polyethylene or tetrafluoroethylene (TFE) wash bottles may be used,
but they may introduce a positive bias due to contamination from
the bottle. It is recommended that acetone not be stored in
polyethylene or TFE bottles for longer than a month.
6.2.3 Glass sample storage containers. Chemically resistant,
borosilicate glass bottles, for acetone and methylene chloride
washes and impinger water, 500 ml or 1,000 ml. Screw-cap liners
shall either be rubber-backed Teflon ® or shall be constructed so
as to be leak-free and resistant to chemical attack by acetone or
methylene chloride. (Narrow-mouth glass bottles have been found to
be less prone to leakage.) Alternatively, polyethylene bottles may
be used.
6.2.4 Petri dishes. For filter samples, glass, unless otherwise
specified by the Administrator.
6.2.5 Graduated cylinder and/or balance. To measure condensed
water, acetone wash and methylene chloride wash used during field
recovery of the samples, to within 1 ml or 1 g. Graduated cylinders
shall have subdivisions no greater than 2 ml. Most laboratory
balances are capable of weighing to the nearest 0.5 g or less. Any
such balance is suitable for use here and in section 6.3.4 of this
method.
6.2.6 Plastic storage containers. Air-tight containers to store
silica gel.
6.2.7 Funnel and rubber policeman. To aid in transfer of silica
gel to container; not necessary if silica gel is weighed in the
field.
6.2.8 Funnel. Glass or polyethylene, to aid in sample
recovery.
6.3 Sample analysis. The following equipment is required for
sample analysis:
6.3.1 Glass or Teflon ® weighing dishes.
6.3.2 Desiccator. It is recommended that fresh desiccant be used
to minimize the chance for positive bias due to absorption of
organic material during drying.
6.3.3 Analytical balance. To measure to within 0.l mg.
6.3.4 Balance. To measure to within 0.5 g.
6.3.5 Beakers. 250 ml.
6.3.6 Hygrometer. To measure the relative humidity of the
laboratory environment.
6.3.7 Temperature sensor. To measure the temperature of the
laboratory environment.
6.3.8 Buchner fritted funnel. 30 ml size, fine (<50
micron)-porosity fritted glass.
6.3.9 Pressure filtration apparatus.
6.3.10 Aluminum dish. Flat bottom, smooth sides, and flanged
top, 18 mm deep and with an inside diameter of approximately 60
mm.
7.0 Reagents and Standards
7.l Sample collection. The following reagents are required for
sample collection:
7.1.1 Filters. Glass fiber filters, without organic binder,
exhibiting at least 99.95 percent efficiency (<0.05 percent
penetration) on 0.3 micron dioctyl phthalate smoke particles. The
filter efficiency test shall be conducted in accordance with ASTM
Method D 2986-95A (incorporated by reference in § 63.841 of this
part). Test data from the supplier's quality control program are
sufficient for this purpose. In sources containing S02 or S03, the
filter material must be of a type that is unreactive to S02 or S03.
Reference 10 in section 17.0 of this method may be used to select
the appropriate filter.
7.1.2 Silica gel. Indicating type, 6 to l6 mesh. If previously
used, dry at l75 °C (350 °F) for 2 hours. New silica gel may be
used as received. Alternatively, other types of desiccants
(equivalent or better) may be used, subject to the approval of the
Administrator.
7.1.3 Water. When analysis of the material caught in the
impingers is required, deionized distilled water shall be used. Run
blanks prior to field use to eliminate a high blank on test
samples.
7.1.4 Crushed ice.
7.1.5 Stopcock grease. Acetone-insoluble, heat-stable silicone
grease. This is not necessary if screw-on connectors with Teflon”
sleeves, or similar, are used. Alternatively, other types of
stopcock grease may be used, subject to the approval of the
Administrator. [Caution: Many stopcock greases are methylene
chloride-soluble. Use sparingly and carefully remove prior to
recovery to prevent contamination of the MCEM analysis.]
7.2 Sample recovery. The following reagents are required for
sample recovery:
7.2.1 Acetone. Acetone with blank values <1 ppm, by weight
residue, is required. Acetone blanks may be run prior to field use,
and only acetone with low blank values may be used. In no case
shall a blank value of greater than 1E-06 of the weight of acetone
used be subtracted from the sample weight.
Note:
This is more restrictive than Method 5, 40 CFR part 60, appendix
A. At least one vendor (Supelco Incorporated located in Bellefonte,
Pennsylvania) lists <1 mg/l as residue for its Environmental
Analysis Solvents.
7.2.2 Methylene chloride. Methylene chloride with a blank value
<1.5 ppm, by weight, residue. Methylene chloride blanks may be
run prior to field use, and only methylene chloride with low blank
values may be used. In no case shall a blank value of greater than
1.6E-06 of the weight of methylene chloride used be subtracted from
the sample weight.
Note:
A least one vendor quotes <1 mg/l for Environmental Analysis
Solvents-grade methylene chloride.
7.3 Sample analysis. The following reagents are required for
sample analysis:
7.3.l Acetone. Same as in section 7.2.1 of this method.
7.3.2 Desiccant. Anhydrous calcium sulfate, indicating type.
Alternatively, other types of desiccants may be used, subject to
the approval of the Administrator.
7.3.3 Methylene chloride. Same as in section 7.2.2 of this
method.
8.0 Sample Collection, Preservation, Storage, and Transport Note:
The complexity of this method is such that, in order to obtain
reliable results, testers should be trained and experienced with
the test procedures.
8.1 Pretest preparation. It is suggested that sampling equipment
be maintained according to the procedures described in APTD-0576.
Alternative mercury-free thermometers may be used if the
thermometers are at a minimum equivalent in terms of performance or
suitably effective for the specific temperature measurement
application.
8.1.1 Weigh several 200 g to 300 g portions of silica gel in
airtight containers to the nearest 0.5 g. Record on each container
the total weight of the silica gel plus container. As an
alternative, the silica gel need not be preweighed but may be
weighed directly in its impinger or sampling holder just prior to
train assembly.
8.1.2 A batch of glass fiber filters, no more than 50 at a time,
should placed in a soxhlet extraction apparatus and extracted using
methylene chloride for at least 16 hours. After extraction, check
filters visually against light for irregularities, flaws, or
pinhole leaks. Label the shipping containers (glass or plastic
petri dishes), and keep the filters in these containers at all
times except during sampling and weighing.
8.1.3 Desiccate the filters at 20 ±5.6 °C (68 ±10 °F) and
ambient pressure for at least 24 hours and weigh at intervals of at
least 6 hours to a constant weight, i.e., <0.5 mg change from
previous weighing; record results to the nearest 0.1 mg. During
each weighing the filter must not be exposed to the laboratory
atmosphere for longer than 2 minutes and a relative humidity above
50 percent. Alternatively (unless otherwise specified by the
Administrator), the filters may be oven-dried at 104 °C (220 °F)
for 2 to 3 hours, desiccated for 2 hours, and weighed. Procedures
other than those described, which account for relative humidity
effects, may be used, subject to the approval of the
Administrator.
8.2 Preliminary determinations.
8.2.1 Select the sampling site and the minimum number of
sampling points according to Method 1, 40 CFR part 60, appendix A
or as specified by the Administrator. Determine the stack pressure,
temperature, and the range of velocity heads using Method 2, 40 CFR
part 60, appendix A; it is recommended that a leak check of the
pitot lines (see section 8.1 of Method 2, 40 CFR part 60, appendix
A) be performed. Determine the moisture content using Approximation
Method 4 (section 1.2 of Method 4, 40 CFR part 60, appendix A) or
its alternatives to make isokinetic sampling rate settings.
Determine the stack gas dry molecular weight, as described in
section 8.6 of Method 2, 40 CFR part 60, appendix A; if integrated
Method 3 sampling is used for molecular weight determination, the
integrated bag sample shall be taken simultaneously with, and for
the same total length of time as, the particulate sample run.
8.2.2 Select a nozzle size based on the range of velocity heads
such that it is not necessary to change the nozzle size in order to
maintain isokinetic sampling rates. During the run, do not change
the nozzle size. Ensure that the proper differential pressure gauge
is chosen for the range of velocity heads encountered (see section
8.2 of Method 2, 40 CFR part 60, appendix A).
8.2.3 Select a suitable probe liner and probe length such that
all traverse points can be sampled. For large stacks, consider
sampling from opposite sides of the stack to reduce the required
probe length.
8.2.4 Select a total sampling time greater than or equal to the
minimum total sampling time specified in the test procedures for
the specific industry such that: (1) The sampling time per point is
not less than 2 minutes (or some greater time interval as specified
by the Administrator); and (2) the sample volume taken (corrected
to standard conditions) will exceed the required minimum total gas
sample volume. The latter is based on an approximate average
sampling rate.
8.2.5 The sampling time at each point shall be the same. It is
recommended that the number of minutes sampled at each point be an
integer or an integer plus one-half minute, in order to eliminate
timekeeping errors.
8.2.6 In some circumstances (e.g., batch cycles), it may be
necessary to sample for shorter times at the traverse points and to
obtain smaller gas sample volumes. In these cases, the
Administrator's approval must first be obtained.
8.3 Preparation of sampling train.
8.3.1 During preparation and assembly of the sampling train,
keep all openings where contamination can occur covered until just
prior to assembly or until sampling is about to begin. Place l00 ml
of water in each of the first two impingers, leave the third
impinger empty, and transfer approximately 200 to 300 g of
preweighed silica gel from its container to the fourth impinger.
More silica gel may be used, but care should be taken to ensure
that it is not entrained and carried out from the impinger during
sampling. Place the container in a clean place for later use in the
sample recovery. Alternatively, the weight of the silica gel plus
impinger may be determined to the nearest 0.5 g and recorded.
8.3.2 Using a tweezer or clean disposable surgical gloves, place
a labeled (identified) and weighed filter in the filter holder. Be
sure that the filter is properly centered and the gasket properly
placed so as to prevent the sample gas stream from circumventing
the filter. Check the filter for tears after assembly is
completed.
8.3.3 When glass liners are used, install the selected nozzle
using a Viton A 0-ring when stack temperatures are less than 260 °C
(500 °F) and an asbestos string gasket when temperatures are
higher. See APTD-0576 for details. Mark the probe with
heat-resistant tape or by some other method to denote the proper
distance into the stack or duct for each sampling point.
8.3.4 Set up the train as in Figure 5-1 of Method 5, 40 CFR part
60, appendix A, using (if necessary) a very light coat of silicone
grease on all ground glass joints, greasing only the outer portion
(see APTD-0576) to avoid possibility of contamination by the
silicone grease. Subject to the approval of the Administrator, a
glass cyclone may be used between the probe and filter holder when
the total particulate catch is expected to exceed 100 mg or when
water droplets are present in the stack gas.
8.3.5 Place crushed ice around the impingers.
8.4 Leak-check procedures.
8.4.1 Leak check of metering system shown in Figure 5-1 of
Method 5, 40 CFR part 60, appendix A. That portion of the sampling
train from the pump to the orifice meter should be leak-checked
prior to initial use and after each shipment. Leakage after the
pump will result in less volume being recorded than is actually
sampled. The following procedure is suggested (see Figure 5-2 of
Method 5, 40 CFR part 60, appendix A): Close the main valve on the
meter box. Insert a one-hole rubber stopper with rubber tubing
attached into the orifice exhaust pipe. Disconnect and vent the low
side of the orifice manometer. Close off the low side orifice tap.
Pressurize the system to 13 to 18 cm (5 to 7 in.) water column by
blowing into the rubber tubing. Pinch off the tubing, and observe
the manometer for 1 minute. A loss of pressure on the manometer
indicates a leak in the meter box; leaks, if present, must be
corrected.
8.4.2 Pretest leak check. A pretest leak-check is recommended
but not required. If the pretest leak-check is conducted, the
following procedure should be used.
8.4.2.1 After the sampling train has been assembled, turn on and
set the filter and probe heating systems to the desired operating
temperatures. Allow time for the temperatures to stabilize. If a
Viton A 0-ring or other leak-free connection is used in assembling
the probe nozzle to the probe liner, leak-check the train at the
sampling site by plugging the nozzle and pulling a 380 mm (15 in.)
Hg vacuum.
Note:
A lower vacuum may be used, provided that it is not exceeded
during the test.
8.4.2.2 If an asbestos string is used, do not connect the probe
to the train during the leak check. Instead, leak-check the train
by first plugging the inlet to the filter holder (cyclone, if
applicable) and pulling a 380 mm (15 in.) Hg vacuum. (See NOTE in
section 8.4.2.1 of this method). Then connect the probe to the
train and perform the leak check at approximately 25 mm (1 in.) Hg
vacuum; alternatively, the probe may be leak-checked with the rest
of the sampling train, in one step, at 380 mm (15 in.) Hg vacuum.
Leakage rates in excess of 4 percent of the average sampling rate
or 0.00057 m 3/min (0.02 cfm), whichever is less, are
unacceptable.
8.4.2.3 The following leak check instructions for the sampling
train described in APTD-0576 and APTD-058l may be helpful. Start
the pump with the bypass valve fully open and the coarse adjust
valve completely closed. Partially open the coarse adjust valve and
slowly close the bypass valve until the desired vacuum is reached.
Do not reverse the direction of the bypass valve, as this
will cause water to back up into the filter holder. If the desired
vacuum is exceeded, either leak-check at this higher vacuum or end
the leak check as shown below and start over.
8.4.2.4 When the leak check is completed, first slowly remove
the plug from the inlet to the probe, filter holder, or cyclone (if
applicable) and immediately turn off the vacuum pump. This prevents
the water in the impingers from being forced backward into the
filter holder and the silica gel from being entrained backward into
the third impinger.
8.4.3 Leak checks during sample run. If, during the sampling
run, a component (e.g., filter assembly or impinger) change becomes
necessary, a leak check shall be conducted immediately before the
change is made. The leak check shall be done according to the
procedure outlined in section 8.4.2 of this method, except that it
shall be done at a vacuum equal to or greater than the maximum
value recorded up to that point in the test. If the leakage rate is
found to be no greater than 0.00057 m 3/min (0.02 cfm) or 4 percent
of the average sampling rate (whichever is less), the results are
acceptable, and no correction will need to be applied to the total
volume of dry gas metered; if, however, a higher leakage rate is
obtained, either record the leakage rate and plan to correct the
sample volume as shown in section 12.3 of this method or void the
sample run.
Note:
Immediately after component changes, leak checks are optional;
if such leak checks are done, the procedure outlined in section
8.4.2 of this method should be used.
8.4.4 Post-test leak check. A leak check is mandatory at the
conclusion of each sampling run. The leak check shall be performed
in accordance with the procedures outlined in section 8.4.2 of this
method, except that it shall be conducted at a vacuum equal to or
greater than the maximum value reached during the sampling run. If
the leakage rate is found to be no greater than 0.00057 m 3/min
(0.02 cfm) or 4 percent of the average sampling rate (whichever is
less), the results are acceptable, and no correction need be
applied to the total volume of dry gas metered. If, however, a
higher leakage rate is obtained, either record the leakage rate and
correct the sample volume, as shown in section 12.4 of this method,
or void the sampling run.
8.5 Sampling train operation. During the sampling run, maintain
an isokinetic sampling rate (within l0 percent of true isokinetic
unless otherwise specified by the Administrator) and a temperature
around the filter of 120 14 °C (248 25 °F), or such other
temperature as specified by an applicable subpart of the standards
or approved by the Administrator.
8.5.1 For each run, record the data required on a data sheet
such as the one shown in Figure 5-2 of Method 5, 40 CFR part 60,
appendix A. Be sure to record the initial reading. Record the DGM
readings at the beginning and end of each sampling time increment,
when changes in flow rates are made, before and after each
leak-check, and when sampling is halted. Take other readings
indicated by Figure 5-2 of Method 5, 40 CFR part 60, appendix A at
least once at each sample point during each time increment and
additional readings when significant changes (20 percent variation
in velocity head readings) necessitate additional adjustments in
flow rate. Level and zero the manometer. Because the manometer
level and zero may drift due to vibrations and temperature changes,
make periodic checks during the traverse.
8.5.2 Clean the portholes prior to the test run to minimize the
chance of sampling deposited material. To begin sampling, remove
the nozzle cap and verify that the filter and probe heating systems
are up to temperature and that the pitot tube and probe are
properly positioned. Position the nozzle at the first traverse
point with the tip pointing directly into the gas stream.
Immediately start the pump and adjust the flow to isokinetic
conditions. Nomographs are available, which aid in the rapid
adjustment of the isokinetic sampling rate without excessive
computations. These nomographs are designed for use when the Type S
pitot tube coefficient (Cp) is 0.85 # 0.02 and the stack gas
equivalent density (dry molecular weight) is 29 ±4. APTD-0576
details the procedure for using the nomographs. If Cp and Md are
outside the above-stated ranges, do not use the nomographs unless
appropriate steps (see Reference 7 in section 17.0 of this method)
are taken to compensate for the deviations.
8.5.3 When the stack is under significant negative pressure
(height of impinger stem), close the coarse adjust valve before
inserting the probe into the stack to prevent water from backing
into the filter holder. If necessary, the pump may be turned on
with the coarse adjust valve closed.
8.5.4 When the probe is in position, block off the openings
around the probe and porthole to prevent unrepresentative dilution
of the gas stream.
8.5.5 Traverse the stack cross-section, as required by Method 1,
40 CFR part 60, appendix A or as specified by the Administrator,
being careful not to bump the probe nozzle into the stack walls
when sampling near the walls or when removing or inserting the
probe through the portholes; this minimizes the chance of
extracting deposited material.
8.5.6 During the test run, make periodic adjustments to keep the
temperature around the filter holder at the proper level; add more
ice and, if necessary, salt to maintain a temperature of less than
20 °C (68 °F) at the condenser/silica gel outlet. Also,
periodically check the level and zero of the manometer.
8.5.7 If the pressure drop across the filter becomes too high,
making isokinetic sampling difficult to maintain, the filter may be
replaced in the midst of the sample run. It is recommended that
another complete filter assembly be used rather than attempting to
change the filter itself. Before a new filter assembly is
installed, conduct a leak check (see section 8.4.3 of this method).
The total PM weight shall include the summation of the filter
assembly catches.
8.5.8 A single train shall be used for the entire sample run,
except in cases where simultaneous sampling is required in two or
more separate ducts or at two or more different locations within
the same duct, or in cases where equipment failure necessitates a
change of trains. In all other situations, the use of two or more
trains will be subject to the approval of the Administrator.
Note:
When two or more trains are used, separate analyses of the
front-half and (if applicable) impinger catches from each train
shall be performed, unless identical nozzle sizes were used in all
trains, in which case the front-half catches from the individual
trains may be combined (as may the impinger catches) and one
analysis of the front-half catch and one analysis of the impinger
catch may be performed.
8.5.9 At the end of the sample run, turn off the coarse adjust
valve, remove the probe and nozzle from the stack, turn off the
pump, record the final DGM reading, and then conduct a post-test
leak check, as outlined in section 8.4.4 of this method. Also
leak-check the pitot lines as described in section 8.1 of Method 2,
40 CFR part 60, appendix A. The lines must pass this leak check in
order to validate the velocity head data.
8.6 Calculation of percent isokinetic. Calculate percent
isokinetic (see Calculations, section 12.12 of this method) to
determine whether a run was valid or another test run should be
made. If there was difficulty in maintaining isokinetic rates
because of source conditions, consult the Administrator for
possible variance on the isokinetic rates.
8.7 Sample recovery.
8.7.1 Proper cleanup procedure begins as soon as the probe is
removed from the stack at the end of the sampling period. Allow the
probe to cool.
8.7.2 When the probe can be safely handled, wipe off all
external PM near the tip of the probe nozzle and place a cap over
it to prevent losing or gaining PM. Do not cap off the probe tip
tightly while the sampling train is cooling down. This would create
a vacuum in the filter holder, thus drawing water from the
impingers into the filter holder.
8.7.3 Before moving the sample train to the cleanup site, remove
the probe from the sample train, wipe off the silicone grease, and
cap the open outlet of the probe. Be careful not to lose any
condensate that might be present. Wipe off the silicone grease from
the filter inlet where the probe was fastened and cap it. Remove
the umbilical cord from the last impinger and cap the impinger. If
a flexible line is used between the first impinger or condenser and
the filter holder, disconnect the line at the filter holder and let
any condensed water or liquid drain into the impingers or
condenser. After wiping off the silicone grease, cap off the filter
holder outlet and impinger inlet. Ground-glass stoppers, plastic
caps, or serum caps may be used to close these openings.
8.7.4 Transfer the probe and filter-impinger assembly to the
cleanup area. This area should be clean and protected from the wind
so that the chances of contaminating or losing the sample will be
minimized.
8.7.5 Save a portion of the acetone and methylene chloride used
for cleanup as blanks. Take 200 ml of each solvent directly from
the wash bottle being used and place it in glass sample containers
labeled “acetone blank” and “methylene chloride blank,”
respectively.
8.7.6 Inspect the train prior to and during disassembly and note
any abnormal conditions. Treat the samples as follows:
8.7.6.1 Container No. 1. Carefully remove the filter from the
filter holder, and place it in its identified petri dish container.
Use a pair of tweezers and/or clean disposable surgical gloves to
handle the filter. If it is necessary to fold the filter, do so
such that the PM cake is inside the fold. Using a dry nylon bristle
brush and/or a sharp-edged blade, carefully transfer to the petri
dish any PM and/or filter fibers that adhere to the filter holder
gasket. Seal the container.
8.7.6.2 Container No. 2. Taking care to see that dust on the
outside of the probe or other exterior surfaces does not get into
the sample, quantitatively recover PM or any condensate from the
probe nozzle, probe fitting, probe liner, and front half of the
filter holder by washing these components with acetone and placing
the wash in a glass container. Perform the acetone rinse as
follows:
8.7.6.2.1 Carefully remove the probe nozzle and clean the inside
surface by rinsing with acetone from a wash bottle and brushing
with a nylon bristle brush. Brush until the acetone rinse shows no
visible particles, after which make a final rinse of the inside
surface with acetone.
8.7.6.2.2 Brush and rinse the inside parts of the Swagelok
fitting with acetone in a similar way until no visible particles
remain.
8.7.6.2.3 Rinse the probe liner with acetone by tilting and
rotating the probe while squirting acetone into its upper end so
that all inside surfaces are wetted with acetone. Let the acetone
drain from the lower end into the sample container. A funnel (glass
or polyethylene) may be used to aid in transferring liquid washes
to the container. Follow the acetone rinse with a probe brush. Hold
the probe in an inclined position, squirt acetone into the upper
end as the probe brush is being pushed with a twisting action
through the probe, hold a sample container under the lower end of
the probe, and catch any acetone and PM that is brushed from the
probe. Run the brush through the probe three times or more until no
visible PM is carried out with the acetone or until none remains in
the probe liner on visual inspection. With stainless steel or other
metal probes, run the brush through in the above-described manner
at least six times, since metal probes have small crevices in which
PM can be entrapped. Rinse the brush with acetone and
quantitatively collect these washings in the sample container.
After the brushing, make a final acetone rinse of the probe as
described above.
8.7.6.2.4 It is recommended that two people clean the probe to
minimize sample losses. Between sampling runs, keep brushes clean
and protected from contamination.
8.7.6.2.5 After ensuring that all joints have been wiped clean
of silicone grease, clean the inside of the front half of the
filter holder by rubbing the surfaces with a nylon bristle brush
and rinsing with acetone. Rinse each surface three times or more if
needed to remove visible particulate. Make a final rinse of the
brush and filter holder. Carefully rinse out the glass cyclone also
(if applicable).
8.7.6.2.6 After rinsing the nozzle, probe, and front half of the
filter holder with acetone, repeat the entire procedure with
methylene chloride and save in a separate No. 2M container.
8.7.6.2.7 After acetone and methylene chloride washings and PM
have been collected in the proper sample containers, tighten the
lid on the sample containers so that acetone and methylene chloride
will not leak out when it is shipped to the laboratory. Mark the
height of the fluid level to determine whether leakage occurs
during transport. Label each container to identify clearly its
contents.
8.7.6.3 Container No. 3. Note the color of the indicating silica
gel to determine whether it has been completely spent, and make a
notation of its condition. Transfer the silica gel from the fourth
impinger to its original container and seal the container. A funnel
may make it easier to pour the silica gel without spilling. A
rubber policeman may be used as an aid in removing the silica gel
from the impinger. It is not necessary to remove the small amount
of dust particles that may adhere to the impinger wall and are
difficult to remove. Since the gain in weight is to be used for
moisture calculations, do not use any water or other liquids to
transfer the silica gel. If a balance is available in the field,
follow the procedure for Container No. 3 in section 11.2.3 of this
method.
8.7.6.4 Impinger water. Treat the impingers as follows:
8.7.6.4.1 Make a notation of any color or film in the liquid
catch. Measure the liquid that is in the first three impingers to
within 1 ml by using a graduated cylinder or by weighing it to
within 0.5 g by using a balance (if one is available). Record the
volume or weight of liquid present. This information is required to
calculate the moisture content of the effluent gas.
8.7.6.4.2 Following the determination of the volume of liquid
present, rinse the back half of the train with water, add it to the
impinger catch, and store it in a container labeled 3W (water).
8.7.6.4.3 Following the water rinse, rinse the back half of the
train with acetone to remove the excess water to enhance subsequent
organic recovery with methylene chloride and quantitatively recover
to a container labeled 3S (solvent) followed by at least three
sequential rinsings with aliquots of methylene chloride.
Quantitatively recover to the same container labeled 3S. Record
separately the amount of both acetone and methylene chloride used
to the nearest 1 ml or 0.5g.
Note:
Because the subsequent analytical finish is gravimetric, it is
okay to recover both solvents to the same container. This would not
be recommended if other analytical finishes were required.
8.8 Sample transport. Whenever possible, containers should be
shipped in such a way that they remain upright at all times.
9.0 Quality Control
9.1 Miscellaneous quality control measures.
Section |
Quality control measure |
Effect |
8.4,
10.1-10.6 |
Sampling and equipment leak
check and calibration |
Ensure accurate measurement of
stack gas flow rate, sample volume. |
9.2 Volume metering system checks. The following quality control
procedures are suggested to check the volume metering system
calibration values at the field test site prior to sample
collection. These procedures are optional.
9.2.1 Meter orifice check. Using the calibration data obtained
during the calibration procedure described in section 10.3 of this
method, determine the ΔHa for the metering system orifice. The ΔHa
is the orifice pressure differential in units of in. H20 that
correlates to 0.75 cfm of air at 528 °R and 29.92 in. Hg. The ΔHa
is calculated as follows:

Where
0.0319 = (0.0567 in. Hg/ °R)(0.75 cfm) 2; ΔH = Average pressure
differential across the orifice meter, in. H20; Tm = Absolute
average DGM temperature, °R; Θ = Total sampling time, min; Pbar =
Barometric pressure, in. Hg; Y = DGM calibration factor,
dimensionless; Vm = Volume of gas sample as measured by DGM, dcf.
9.2.1.1 Before beginning the field test (a set of three runs
usually constitutes a field test), operate the metering system
(i.e., pump, volume meter, and orifice) at the ΔHa pressure
differential for 10 minutes. Record the volume collected, the DGM
temperature, and the barometric pressure. Calculate a DGM
calibration check value, Yc, as follows:

Where Yc
= DGM calibration check value, dimensionless; 10 = Run time, min.
9.2.1.2 Compare the Yc value with the dry gas meter calibration
factor Y to determine that: 0.97 Y <Yc <1.03Y. If the Yc
value is not within this range, the volume metering system should
be investigated before beginning the test.
9.2.2 Calibrated critical orifice. A calibrated critical
orifice, calibrated against a wet test meter or spirometer and
designed to be inserted at the inlet of the sampling meter box, may
be used as a quality control check by following the procedure of
section 16.2 of this method.
10.0 Calibration and Standardization Note:
Maintain a laboratory log of all calibrations.
10.1 Probe nozzle. Probe nozzles shall be calibrated before
their initial use in the field. Using a micrometer, measure the ID
of the nozzle to the nearest 0.025 mm (0.001 in.). Make three
separate measurements using different diameters each time, and
obtain the average of the measurements. The difference between the
high and low numbers shall not exceed 0.1 mm (0.004 in.). When
nozzles become nicked, dented, or corroded, they shall be reshaped,
sharpened, and recalibrated before use. Each nozzle shall be
permanently and uniquely identified.
10.2 Pitot tube assembly. The Type S pitot tube assembly shall
be calibrated according to the procedure outlined in section 10.1
of Method 2, 40 CFR part 60, appendix A.
10.3 Metering system.
10.3.1 Calibration prior to use. Before its initial use in the
field, the metering system shall be calibrated as follows: Connect
the metering system inlet to the outlet of a wet test meter that is
accurate to within 1 percent. Refer to Figure 5-5 of Method 5, 40
CFR part 60, appendix A. The wet test meter should have a capacity
of 30 liters/revolution (1 ft 3/rev). A spirometer of 400 liters
(14 ft 3) or more capacity, or equivalent, may be used for this
calibration, although a wet test meter is usually more practical.
The wet test meter should be periodically calibrated with a
spirometer or a liquid displacement meter to ensure the accuracy of
the wet test meter. Spirometers or wet test meters of other sizes
may be used, provided that the specified accuracies of the
procedure are maintained. Run the metering system pump for about 15
minutes with the orifice manometer indicating a median reading, as
expected in field use, to allow the pump to warm up and to permit
the interior surface of the wet test meter to be thoroughly wetted.
Then, at each of a minimum of three orifice manometer settings,
pass an exact quantity of gas through the wet test meter and note
the gas volume indicated by the DGM. Also note the barometric
pressure and the temperatures of the wet test meter, the inlet of
the DGM, and the outlet of the DGM. Select the highest and lowest
orifice settings to bracket the expected field operating range of
the orifice. Use a minimum volume of 0.15 m 3 (5 cf) at all orifice
settings. Record all the data on a form similar to Figure 5-6 of
Method 5, 40 CFR part 60, appendix A, and calculate Y (the DGM
calibration factor) and ΔHa (the orifice calibration factor) at
each orifice setting, as shown on Figure 5-6 of Method 5, 40 CFR
part 60, appendix A. Allowable tolerances for individual Y and ΔHa
values are given in Figure 5-6 of Method 5, 40 CFR part 60,
appendix A. Use the average of the Y values in the calculations in
section 12 of this method.
10.3.1.1 Before calibrating the metering system, it is suggested
that a leak check be conducted. For metering systems having
diaphragm pumps, the normal leak check procedure will not detect
leakages within the pump. For these cases the following leak check
procedure is suggested: make a 10-minute calibration run at 0.00057
m 3/min (0.02 cfm); at the end of the run, take the difference of
the measured wet test meter and DGM volumes; divide the difference
by 10 to get the leak rate. The leak rate should not exceed 0.00057
m 3/min (0.02 cfm).
10.3.2 Calibration after use. After each field use, the
calibration of the metering system shall be checked by performing
three calibration runs at a single, intermediate orifice setting
(based on the previous field test) with the vacuum set at the
maximum value reached during the test series. To adjust the vacuum,
insert a valve between the wet test meter and the inlet of the
metering system. Calculate the average value of the DGM calibration
factor. If the value has changed by more than 5 percent,
recalibrate the meter over the full range of orifice settings, as
previously detailed.
Note:
Alternative procedures, e.g., rechecking the orifice meter
coefficient, may be used, subject to the approval of the
Administrator.
10.3.3 Acceptable variation in calibration. If the DGM
coefficient values obtained before and after a test series differ
by more than 5 percent, either the test series shall be voided or
calculations for the test series shall be performed using whichever
meter coefficient value (i.e., before or after) gives the lower
value of total sample volume.
10.4 Probe heater calibration. Use a heat source to generate air
heated to selected temperatures that approximate those expected to
occur in the sources to be sampled. Pass this air through the probe
at a typical sample flow rate while measuring the probe inlet and
outlet temperatures at various probe heater settings. For each air
temperature generated, construct a graph of probe heating system
setting versus probe outlet temperature. The procedure outlined in
APTD-0576 can also be used. Probes constructed according to
APTD-0581 need not be calibrated if the calibration curves in
APTD-0576 are used. Also, probes with outlet temperature monitoring
capabilities do not require calibration.
Note:
The probe heating system shall be calibrated before its initial
use in the field.
10.5 Temperature sensors. Use the procedure in Section 10.3 of
Method 2, 40 CFR part 60, appendix A-1 to calibrate in-stack
temperature sensors. Dial thermometers, such as are used for the
DGM and condenser outlet, shall be calibrated against
mercury-in-glass thermometers. An alternative mercury-free
thermometer may be used if the thermometer is, at a minimum,
equivalent in terms of performance or suitably effective for the
specific temperature measurement application.
10.6 Barometer. Calibrate against a mercury barometer.
11.0 Analytical Procedure
11.1 Record the data required on a sheet such as the one shown
in Figure 315-1 of this method.
11.2 Handle each sample container as follows:
11.2.1 Container No. 1.
11.2.1.1 PM analysis. Leave the contents in the shipping
container or transfer the filter and any loose PM from the sample
container to a tared glass weighing dish. Desiccate for 24 hours in
a desiccator containing anhydrous calcium sulfate. Weigh to a
constant weight and report the results to the nearest 0.1 mg. For
purposes of this section, the term “constant weight” means a
difference of no more than 0.5 mg or 1 percent of total weight less
tare weight, whichever is greater, between two consecutive
weighings, with no less than 6 hours of desiccation time between
weighings (overnight desiccation is a common practice). If a third
weighing is required and it agrees within ±0.5 mg, then the results
of the second weighing should be used. For quality assurance
purposes, record and report each individual weighing; if more than
three weighings are required, note this in the results for the
subsequent MCEM results.
11.2.1.2 MCEM analysis. Transfer the filter and contents
quantitatively into a beaker. Add 100 ml of methylene chloride and
cover with aluminum foil. Sonicate for 3 minutes then allow to
stand for 20 minutes. Set up the filtration apparatus. Decant the
solution into a clean Buchner fritted funnel. Immediately pressure
filter the solution through the tube into another clean, dry
beaker. Continue decanting and pressure filtration until all the
solvent is transferred. Rinse the beaker and filter with 10 to 20
ml methylene chloride, decant into the Buchner fritted funnel and
pressure filter. Place the beaker on a low-temperature hot plate
(maximum 40 °C) and slowly evaporate almost to dryness. Transfer
the remaining last few milliliters of solution quantitatively from
the beaker (using at least three aliquots of methylene chloride
rinse) to a tared clean dry aluminum dish and evaporate to complete
dryness. Remove from heat once solvent is evaporated. Reweigh the
dish after a 30-minute equilibrium in the balance room and
determine the weight to the nearest 0.1 mg. Conduct a methylene
chloride blank run in an identical fashion.
11.2.2 Container No. 2.
11.2.2.1 PM analysis. Note the level of liquid in the container,
and confirm on the analysis sheet whether leakage occurred during
transport. If a noticeable amount of leakage has occurred, either
void the sample or use methods, subject to the approval of the
Administrator, to correct the final results. Measure the liquid in
this container either volumetrically to ±1 ml or gravimetrically to
1 ±0.5 g. Transfer the contents to a tared 250 ml beaker and
evaporate to dryness at ambient temperature and pressure. Desiccate
for 24 hours, and weigh to a constant weight. Report the results to
the nearest 0.1 mg.
11.2.2.2 MCEM analysis. Add 25 ml methylene chloride to the
beaker and cover with aluminum foil. Sonicate for 3 minutes then
allow to stand for 20 minutes; combine with contents of Container
No. 2M and pressure filter and evaporate as described for Container
1 in section 11.2.1.2 of this method.
Notes for MCEM Analysis
1. Light finger pressure only is necessary on 24/40 adaptor. A
Chemplast adapter #15055-240 has been found satisfactory.
2. Avoid aluminum dishes made with fluted sides, as these may
promote solvent “creep,” resulting in possible sample loss.
3. If multiple samples are being run, rinse the Buchner fritted
funnel twice between samples with 5 ml solvent using pressure
filtration. After the second rinse, continue the flow of air until
the glass frit is completely dry. Clean the Buchner fritted funnels
thoroughly after filtering five or six samples.
11.2.3 Container No. 3. Weigh the spent silica gel (or silica
gel plus impinger) to the nearest 0.5 g using a balance. This step
may be conducted in the field.
11.2.4 Container 3W (impinger water).
11.2.4.1 MCEM analysis. Transfer the solution into a 1,000 ml
separatory funnel quantitatively with methylene chloride washes.
Add enough solvent to total approximately 50 ml, if necessary.
Shake the funnel for 1 minute, allow the phases to separate, and
drain the solvent layer into a 250 ml beaker. Repeat the extraction
twice. Evaporate with low heat (less than 40 °C) until near
dryness. Transfer the remaining few milliliters of solvent
quantitatively with small solvent washes into a clean, dry, tared
aluminum dish and evaporate to dryness. Remove from heat once
solvent is evaporated. Reweigh the dish after a 30-minute
equilibration in the balance room and determine the weight to the
nearest 0.1 mg.
11.2.5 Container 3S (solvent).
11.2.5.1 MCEM analysis. Transfer the mixed solvent to 250 ml
beaker(s). Evaporate and weigh following the procedures detailed
for container 3W in section 11.2.4 of this method.
11.2.6 Blank containers. Measure the distilled water, acetone,
or methylene chloride in each container either volumetrically or
gravimetrically. Transfer the “solvent” to a tared 250 ml beaker,
and evaporate to dryness at ambient temperature and pressure.
(Conduct a solvent blank on the distilled deionized water blank in
an identical fashion to that described in section 11.2.4.1 of this
method.) Desiccate for 24 hours, and weigh to a constant weight.
Report the results to the nearest 0.l mg.
Note:
The contents of Containers No. 2, 3W, and 3M as well as the
blank containers may be evaporated at temperatures higher than
ambient. If evaporation is done at an elevated temperature, the
temperature must be below the boiling point of the solvent; also,
to prevent “bumping,” the evaporation process must be closely
supervised, and the contents of the beaker must be swirled
occasionally to maintain an even temperature. Use extreme care, as
acetone and methylene chloride are highly flammable and have a low
flash point.
12.0 Data Analysis and Calculations
12.1 Carry out calculations, retaining at least one extra
decimal figure beyond that of the acquired data. Round off figures
after the final calculation. Other forms of the equations may be
used as long as they give equivalent results.
12.2 Nomenclature.
An = Cross-sectional area of nozzle, m 3 (ft 3). Bws = Water vapor
in the gas stream, proportion by volume. Ca = Acetone blank residue
concentration, mg/g. Cs = Concentration of particulate matter in
stack gas, dry basis, corrected to standard conditions, g/dscm
(g/dscf). I = Percent of isokinetic sampling. La = Maximum
acceptable leakage rate for either a pretest leak check or for a
leak check following a component change; equal to 0.00057 m 3/min
(0.02 cfm) or 4 percent of the average sampling rate, whichever is
less. Li = Individual leakage rate observed during the leak check
conducted prior to the “i th” component change (I = l, 2, 3...n), m
3/min (cfm). Lp = Leakage rate observed during the post-test leak
check, m 3/min (cfm). ma = Mass of residue of acetone after
evaporation, mg. mn = Total amount of particulate matter collected,
mg. Mw = Molecular weight of water, 18.0 g/g-mole (18.0
lb/lb-mole). Pbar = Barometric pressure at the sampling site, mm Hg
(in Hg). Ps = Absolute stack gas pressure, mm Hg (in. Hg). Pstd =
Standard absolute pressure, 760 mm Hg (29.92 in. Hg). R = Ideal gas
constant, 0.06236 [(mm Hg)(m 3)]/[(°K) (g-mole)] '61' 21.85 [(in.
Hg)(ft 3)]/[(°R)(lb-mole)'61' ]. Tm = Absolute average dry gas
meter (DGM) temperature (see Figure 5-2 of Method 5, 40 CFR part
60, appendix A), °K (°R). Ts = Absolute average stack gas
temperature (see Figure 5-2 of Method 5, 40 CFR part 60, appendix
A), °K(°R). Tstd = Standard absolute temperature, 293 °K (528 °R).
Va = Volume of acetone blank, ml. Vaw = Volume of acetone used in
wash, ml. Vt = Volume of methylene chloride blank, ml. Vtw = Volume
of methylene chloride used in wash, ml. Vlc = Total volume liquid
collected in impingers and silica gel (see Figure 5-3 of Method 5,
40 CFR part 60, appendix A), ml. Vm = Volume of gas sample as
measured by dry gas meter, dcm (dcf). Vm(std) = Volume of gas
sample measured by the dry gas meter, corrected to standard
conditions, dscm (dscf). Vw(std) = Volume of water vapor in the gas
sample, corrected to standard conditions, scm (scf). Vs = Stack gas
velocity, calculated by Equation 2-9 in Method 2, 40 CFR part 60,
appendix A, using data obtained from Method 5, 40 CFR part 60,
appendix A, m/sec (ft/sec). Wa = Weight of residue in acetone wash,
mg. Y = Dry gas meter calibration factor. ΔH = Average pressure
differential across the orifice meter (see Figure 5-2 of Method 5,
40 CFR part 60, appendix A), mm H2O (in H2O). ρa = Density of
acetone, 785.1 mg/ml (or see label on bottle). ρw = Density of
water, 0.9982 g/ml (0.00220l lb/ml). ρt = Density of methylene
chloride, 1316.8 mg/ml (or see label on bottle). Θ = Total sampling
time, min. Θ1 = Sampling time interval, from the beginning of a run
until the first component change, min. Θ1 = Sampling time interval,
between two successive component changes, beginning with the
interval between the first and second changes, min. Θp = Sampling
time interval, from the final (n th) component change until the end
of the sampling run, min. 13.6 = Specific gravity of mercury. 60 =
Sec/min. 100 = Conversion to percent.
12.3 Average dry gas meter temperature and average orifice
pressure drop. See data sheet (Figure 5-2 of Method 5, 40 CFR part
60, appendix A).
12.4 Dry gas volume. Correct the sample volume measured by the
dry gas meter to standard conditions (20 °C, 760 mm Hg or 68 °F,
29.92 in Hg) by using Equation 315-1.

Where Kl
= 0.3858 °K/mm Hg for metric units, = 17.64 °R/in Hg for English
units. Note:
Equation 315-1 can be used as written unless the leakage rate
observed during any of the mandatory leak checks (i.e., the
post-test leak check or leak checks conducted prior to component
changes) exceeds La. If Lp or Li exceeds La, Equation 315-1 must be
modified as follows:
(a) Case I. No component changes made during sampling run. In
this case, replace Vm in Equation 315-1 with the expression:
[Vm - (Lp - La) Θ]
(b) Case II. One or more component changes made during the
sampling run. In this case, replace Vm in Equation 315-1 by the
expression:

and
substitute only for those leakage rates (Li or Lp) which exceed La.
12.5 Volume of water vapor condensed.

Where K2
= 0.001333 m 3/ml for metric units; = 0.04706 ft 3/ml for English
units. 12.6 Moisture content.

Note:
In saturated or water droplet-laden gas streams, two
calculations of the moisture content of the stack gas shall be
made, one from the impinger analysis (Equation 315-3), and a second
from the assumption of saturated conditions. The lower of the two
values of Bws shall be considered correct. The procedure for
determining the moisture content based upon assumption of saturated
conditions is given in section 4.0 of Method 4, 40 CFR part 60,
appendix A. For the purposes of this method, the average stack gas
temperature from Figure 5-2 of Method 5, 40 CFR part 60, appendix A
may be used to make this determination, provided that the accuracy
of the in-stack temperature sensor is ±1 °C (2 °F).
12.7 Acetone blank concentration.
12.8 Acetone wash blank.
Wa = Ca Vaw ρa
Eq. 315-5
12.9 Total particulate weight. Determine the total PM catch from
the sum of the weights obtained from Containers l and 2 less the
acetone blank associated with these two containers (see Figure
315-1).
Note:
Refer to section 8.5.8 of this method to assist in calculation
of results involving two or more filter assemblies or two or more
sampling trains.
12.10 Particulate concentration.
cs = K3 mn/Vm(std) Eq. 315-6 where K = 0.001 g/mg for metric units;
= 0.0154 gr/mg for English units.
12.11 Conversion factors.
From |
To |
Multiply by |
ft
3 |
m 3 |
0.02832 |
gr |
mg |
64.80004 |
gr/ft
3 |
mg/m 3 |
2288.4 |
mg |
g |
0.001 |
gr |
lb |
1.429 × 10−4 |
12.12 Isokinetic variation.
12.12.1 Calculation from raw data.

where K4
= 0.003454 [(mm Hg)(m 3)]/[(m1)(°K)] for metric units; = 0.002669
[(in Hg)(ft 3)]/[(m1)(°R)] for English units.
12.12.2 Calculation from intermediate values.

where K5
= 4.320 for metric units; = 0.09450 for English units.
12.12.3 Acceptable results. If 90 percent ≤I ≤110 percent, the
results are acceptable. If the PM or MCEM results are low in
comparison to the standard, and “I” is over 110 percent or less
than 90 percent, the Administrator may opt to accept the results.
Reference 4 in the Bibliography may be used to make acceptability
judgments. If “I” is judged to be unacceptable, reject the results,
and repeat the test.
12.13 Stack gas velocity and volumetric flow rate. Calculate the
average stack gas velocity and volumetric flow rate, if needed,
using data obtained in this method and the equations in sections
5.2 and 5.3 of Method 2, 40 CFR part 60, appendix A.
12.14 MCEM results. Determine the MCEM concentration from the
results from Containers 1, 2, 2M, 3W, and 3S less the acetone,
methylene chloride, and filter blanks value as determined in the
following equation:
mmcem = S
mtotal −
wa −
wt −
fb
13.0 Method Performance [Reserved] 14.0 Pollution Prevention
[Reserved] 15.0 Waste Management [Reserved] 16.0 Alternative
Procedures
16.1 Dry gas meter as a calibration standard. A DGM may be used
as a calibration standard for volume measurements in place of the
wet test meter specified in section 16.1 of this method, provided
that it is calibrated initially and recalibrated periodically as
follows:
16.1.1 Standard dry gas meter calibration.
16.1.1.1. The DGM to be calibrated and used as a secondary
reference meter should be of high quality and have an appropriately
sized capacity, e.g., 3 liters/rev (0.1 ft 3/rev). A spirometer
(400 liters or more capacity), or equivalent, may be used for this
calibration, although a wet test meter is usually more practical.
The wet test meter should have a capacity of 30 liters/rev (1 ft
3/rev) and be capable of measuring volume to within 1.0 percent;
wet test meters should be checked against a spirometer or a liquid
displacement meter to ensure the accuracy of the wet test meter.
Spirometers or wet test meters of other sizes may be used, provided
that the specified accuracies of the procedure are maintained.
16.1.1.2 Set up the components as shown in Figure 5-7 of Method
5, 40 CFR part 60, appendix A. A spirometer, or equivalent, may be
used in place of the wet test meter in the system. Run the pump for
at least 5 minutes at a flow rate of about 10 liters/min (0.35 cfm)
to condition the interior surface of the wet test meter. The
pressure drop indicated by the manometer at the inlet side of the
DGM should be minimized (no greater than 100 mm H2O [4 in. H2O] at
a flow rate of 30 liters/min [1 cfm]). This can be accomplished by
using large-diameter tubing connections and straight pipe
fittings.
16.1.1.3 Collect the data as shown in the example data sheet
(see Figure 5-8 of Method 5, 40 CFR part 60, appendix A). Make
triplicate runs at each of the flow rates and at no less than five
different flow rates. The range of flow rates should be between 10
and 34 liters/min (0.35 and 1.2 cfm) or over the expected operating
range.
16.1.1.4 Calculate flow rate, Q, for each run using the wet test
meter volume, Vw, and the run time, q. Calculate the DGM
coefficient, Yds, for each run. These calculations are as
follows:

Where K1 = 0.3858
for international system of units (SI); 17.64 for English units;
Pbar = Barometric pressure, mm Hg (in Hg); Vw = Wet test meter
volume, liter (ft 3); tw = Average wet test meter temperature, °C
(°F); tstd = 273 °C for SI units; 460 °F for English units; Θ = Run
time, min; tds = Average dry gas meter temperature, °C (°F); Vds =
Dry gas meter volume, liter (ft 3); Δp = Dry gas meter inlet
differential pressure, mm H2O (in H2O).
16.1.1.5 Compare the three Yds values at each of the flow rates
and determine the maximum and minimum values. The difference
between the maximum and minimum values at each flow rate should be
no greater than 0.030. Extra sets of triplicate runs may be made in
order to complete this requirement. In addition, the meter
coefficients should be between 0.95 and 1.05. If these
specifications cannot be met in three sets of successive triplicate
runs, the meter is not suitable as a calibration standard and
should not be used as such. If these specifications are met,
average the three Yds values at each flow rate resulting in five
average meter coefficients, Yds.
16.1.1.6 Prepare a curve of meter coefficient, Yds, versus flow
rate, Q, for the DGM. This curve shall be used as a reference when
the meter is used to calibrate other DGMs and to determine whether
recalibration is required.
16.1.2 Standard dry gas meter recalibration.
16.1.2.1 Recalibrate the standard DGM against a wet test meter
or spirometer annually or after every 200 hours of operation,
whichever comes first. This requirement is valid provided the
standard DGM is kept in a laboratory and, if transported, cared for
as any other laboratory instrument. Abuse to the standard meter may
cause a change in the calibration and will require more frequent
recalibrations.
16.1.2.2 As an alternative to full recalibration, a two-point
calibration check may be made. Follow the same procedure and
equipment arrangement as for a full recalibration, but run the
meter at only two flow rates (suggested rates are 14 and 28
liters/min [0.5 and 1.0 cfm]). Calculate the meter coefficients for
these two points, and compare the values with the meter calibration
curve. If the two coefficients are within 1.5 percent of the
calibration curve values at the same flow rates, the meter need not
be recalibrated until the next date for a recalibration check.
6.2 Critical orifices as calibration standards. Critical
orifices may be used as calibration standards in place of the wet
test meter specified in section 10.3 of this method, provided that
they are selected, calibrated, and used as follows:
16.2.1 Selection of critical orifices.
16.2.1.1 The procedure that follows describes the use of
hypodermic needles or stainless steel needle tubing that has been
found suitable for use as critical orifices. Other materials and
critical orifice designs may be used provided the orifices act as
true critical orifices; i.e., a critical vacuum can be obtained, as
described in section 7.2.2.2.3 of Method 5, 40 CFR part 60,
appendix A. Select five critical orifices that are appropriately
sized to cover the range of flow rates between 10 and 34 liters/min
or the expected operating range. Two of the critical orifices
should bracket the expected operating range. A minimum of three
critical orifices will be needed to calibrate a Method 5 DGM; the
other two critical orifices can serve as spares and provide better
selection for bracketing the range of operating flow rates. The
needle sizes and tubing lengths shown in Table 315-1 give the
approximate flow rates indicated in the table.
16.2.1.2 These needles can be adapted to a Method 5 type
sampling train as follows: Insert a serum bottle stopper, 13 × 20
mm sleeve type, into a 0.5 in Swagelok quick connect. Insert the
needle into the stopper as shown in Figure 5-9 of Method 5, 40 CFR
part 60, appendix A.
16.2.2 Critical orifice calibration. The procedure described in
this section uses the Method 5 meter box configuration with a DGM
as described in section 6.1.1.9 of this method to calibrate the
critical orifices. Other schemes may be used, subject to the
approval of the Administrator.
16.2.2.1 Calibration of meter box. The critical orifices must be
calibrated in the same configuration as they will be used; i.e.,
there should be no connections to the inlet of the orifice.
16.2.2.1.1 Before calibrating the meter box, leak-check the
system as follows: Fully open the coarse adjust valve and
completely close the bypass valve. Plug the inlet. Then turn on the
pump and determine whether there is any leakage. The leakage rate
shall be zero; i.e., no detectable movement of the DGM dial shall
be seen for 1 minute.
16.2.2.1.2 Check also for leakages in that portion of the
sampling train between the pump and the orifice meter. See section
5.6 of Method 5, 40 CFR part 60, appendix A for the procedure; make
any corrections, if necessary. If leakage is detected, check for
cracked gaskets, loose fittings, worn 0-rings, etc. and make the
necessary repairs.
16.2.2.1.3 After determining that the meter box is leakless,
calibrate the meter box according to the procedure given in section
5.3 of Method 5, 40 CFR part 60, appendix A. Make sure that the wet
test meter meets the requirements stated in section 7.1.1.1 of
Method 5, 40 CFR part 60, appendix A. Check the water level in the
wet test meter. Record the DGM calibration factor, Y.
16.2.2.2 Calibration of critical orifices. Set up the apparatus
as shown in Figure 5-10 of Method 5, 40 CFR part 60, appendix
A.
16.2.2.2.1 Allow a warm-up time of 15 minutes. This step is
important to equilibrate the temperature conditions through the
DGM.
16.2.2.2.2 Leak-check the system as in section 7.2.2.1.1 of
Method 5, 40 CFR part 60, appendix A. The leakage rate shall be
zero.
16.2.2.2.3 Before calibrating the critical orifice, determine
its suitability and the appropriate operating vacuum as follows:
turn on the pump, fully open the coarse adjust valve, and adjust
the bypass valve to give a vacuum reading corresponding to about
half of atmospheric pressure. Observe the meter box orifice
manometer reading, DH. Slowly increase the vacuum reading until a
stable reading is obtained on the meter box orifice manometer.
Record the critical vacuum for each orifice. Orifices that do not
reach a critical value shall not be used.
16.2.2.2.4 Obtain the barometric pressure using a barometer as
described in section 6.1.2 of this method. Record the barometric
pressure, Pbar, in mm Hg (in. Hg).
16.2.2.2.5 Conduct duplicate runs at a vacuum of 25 to 50 mm Hg
(1 to 2 in. Hg) above the critical vacuum. The runs shall be at
least 5 minutes each. The DGM volume readings shall be in
increments of complete revolutions of the DGM. As a guideline, the
times should not differ by more than 3.0 seconds (this includes
allowance for changes in the DGM temperatures) to achieve ±0.5
percent in K′. Record the information listed in Figure 5-11 of
Method 5, 40 CFR part 60, appendix A.
16.2.2.2.6 Calculate K′ using Equation 315-11.

where K′
= Critical orifice coefficient, [m 3)(°K) 1/2]/[(mm Hg)(min)] [(ft
3)(°R) 1/2)]/[(in. Hg)(min)] Tamb = Absolute ambient temperature,
°K (°R).
16.2.2.2.7 Average the K′ values. The individual K′ values
should not differ by more than ±0.5 percent from the average.
16.2.3 Using the critical orifices as calibration standards.
16.2.3.1 Record the barometric pressure.
16.2.3.2 Calibrate the metering system according to the
procedure outlined in sections 7.2.2.2.1 to 7.2.2.2.5 of Method 5,
40 CFR part 60, appendix A. Record the information listed in Figure
5-12 of Method 5, 40 CFR part 60, appendix A.
16.2.3.3 Calculate the standard volumes of air passed through
the DGM and the critical orifices, and calculate the DGM
calibration factor, Y, using the equations below:
Vm(std) = K1 Vm [Pbar + (ΔH/13.6)]/Tm
Eq. 315-12 Vcr(std) =
K′ (Pbar Θ)/Tamb 1/2
Eq. 315-13 Y = Vcr(std)/Vm(std)
Eq.
315-14 where Vcr(std) = Volume of gas sample passed through the
critical orifice, corrected to standard conditions, dscm (dscf). K′
= 0.3858 °K/mm Hg for metric units = 17.64 °R/in Hg for English
units.
16.2.3.4 Average the DGM calibration values for each of the flow
rates. The calibration factor, Y, at each of the flow rates should
not differ by more than ±2 percent from the average.
16.2.3.5 To determine the need for recalibrating the critical
orifices, compare the DGM Y factors obtained from two adjacent
orifices each time a DGM is calibrated; for example, when checking
orifice 13/2.5, use orifices 12/10.2 and 13/5.1. If any critical
orifice yields a DGM Y factor differing by more than 2 percent from
the others, recalibrate the critical orifice according to section
7.2.2.2 of Method 5, 40 CFR part 60, appendix A.
17.0 References
1. Addendum to Specifications for Incinerator Testing at Federal
Facilities. PHS, NCAPC. December 6, 1967.
2. Martin, Robert M. Construction Details of Isokinetic
Source-Sampling Equipment. Environmental Protection Agency.
Research Triangle Park, NC. APTD-0581. April 1971.
3. Rom, Jerome J. Maintenance, Calibration, and Operation of
Isokinetic Source Sampling Equipment. Environmental Protection
Agency. Research Triangle Park, NC. APTD-0576. March 1972.
4. Smith, W.S., R.T. Shigehara, and W.F. Todd. A Method of
Interpreting Stack Sampling Data. Paper Presented at the 63rd
Annual Meeting of the Air Pollution Control Association, St. Louis,
MO. June 14-19, 1970.
5. Smith, W.S., et al. Stack Gas Sampling Improved and
Simplified With New Equipment. APCA Paper No. 67-119. 1967.
6. Specifications for Incinerator Testing at Federal Facilities.
PHS, NCAPC. 1967.
7. Shigehara, R.T. Adjustment in the EPA Nomograph for Different
Pitot Tube Coefficients and Dry Molecular Weights. Stack Sampling
News 2:4-11. October 1974.
8. Vollaro, R.F. A Survey of Commercially Available
Instrumentation for the Measurement of Low-Range Gas Velocities.
U.S. Environmental Protection Agency, Emission Measurement Branch.
Research Triangle Park, NC. November 1976 (unpublished paper).
9. Annual Book of ASTM Standards. Part 26. Gaseous Fuels; Coal
and Coke; Atmospheric Analysis. American Society for Testing and
Materials. Philadelphia, PA. 1974. pp. 617-622.
10. Felix, L.G., G.I. Clinard, G.E. Lacy, and J.D. McCain.
Inertial Cascade Impactor Substrate Media for Flue Gas Sampling.
U.S. Environmental Protection Agency. Research Triangle Park, NC
27711. Publication No. EPA-600/7-77-060. June 1977. 83 p.
11. Westlin, P.R., and R.T. Shigehara. Procedure for Calibrating
and Using Dry Gas Volume Meters as Calibration Standards. Source
Evaluation Society Newsletter. 3 (1):17-30. February
1978.
12. Lodge, J.P., Jr., J.B. Pate, B.E. Ammons, and G.A. Swanson.
The Use of Hypodermic Needles as Critical Orifices in Air Sampling.
J. Air Pollution Control Association. 16:197-200. 1966.
18.0 Tables, Diagrams, Flowcharts, and Validation Data
Table 315-1. Flow Rates for Various Needle
Sizes and Tube Lengths.
Gauge/length
(cm) |
Flow rate
(liters/min) |
Gauge/length
(cm) |
Flow rate
(liters/min) |
12/7.6 |
32.56 |
14/2.5 |
19.54 |
12/10.2 |
30.02 |
14/5.1 |
17.27 |
13/2.5 |
25.77 |
14/7.6 |
16.14 |
13/5.1 |
23.50 |
15/3.2 |
14.16 |
13/7.6 |
22.37 |
15/7.6 |
11.61 |
13/10.2 |
20.67 |
115/10.2 |
10.48 |

Method 316 -
Sampling and Analysis for Formaldehyde Emissions From Stationary
Sources in the Mineral Wool and Wool Fiberglass Industries 1.0
Scope and Application
This method is applicable to the determination of formaldehyde,
CAS Registry number 50-00-0, from stationary sources in the mineral
wool and wool fiber glass industries. High purity water is used to
collect the formaldehyde. The formaldehyde concentrations in the
stack samples are determined using the modified pararosaniline
method. Formaldehyde can be detected as low as 8.8 × 10−10 lbs/cu
ft (11.3 ppbv) or as high as 1.8 × 10−3 lbs/cu ft (23,000,000
ppbv), at standard conditions over a 1-hour sampling period,
sampling approximately 30 cu ft.
2.0 Summary of Method
Gaseous and particulate pollutants are withdrawn isokinetically
from an emission source and are collected in high purity water.
Formaldehyde present in the emissions is highly soluble in high
purity water. The high purity water containing formaldehyde is then
analyzed using the modified pararosaniline method. Formaldehyde in
the sample reacts with acidic pararosaniline, and the sodium
sulfite, forming a purple chromophore. The intensity of the purple
color, measured spectrophotometrically, provides an accurate and
precise measure of the formaldehyde concentration in the
sample.
3.0 Definitions
See the definitions in the General Provisions of this
Subpart.
4.0 Interferences
Sulfite and cyanide in solution interfere with the
pararosaniline method. A procedure to overcome the interference by
each compound has been described by Miksch, et al.
5.0 Safety [Reserved] 6.0 Apparatus and Materials
6.1 A schematic of the sampling train is shown in Figure 1. This
sampling train configuration is adapted from EPA Method 5, 40 CFR
part 60, appendix A, procedures.
The sampling train consists of the following components: probe
nozzle, probe liner, pitot tube, differential pressure gauge,
impingers, metering system, barometer, and gas density
determination equipment.
6.1.1 Probe Nozzle: Quartz, glass, or stainless steel with
sharp, tapered (30 ° angle) leading edge. The taper shall be on the
outside to preserve a constant inner diameter. The nozzle shall be
buttonhook or elbow design. A range of nozzle sizes suitable for
isokinetic sampling should be available in increments of 0.15 cm (
1/16 in), e.g., 0.32 to 1.27 cm ( 1/8 to 1/2 in), or larger if
higher volume sampling trains are used. Each nozzle shall be
calibrated according to the procedure outlined in Section 10.1.
6.1.2 Probe Liner: Borosilicate glass or quartz shall be used
for the probe liner. The probe shall be maintained at a temperature
of 120 °C ±14 °C (248 °F ±25 °F).
6.1.3 Pitot Tube: The pitot tube shall be Type S, as described
in Section 2.1 of EPA Method 2, 40 CFR part 60, appendix A, or any
other appropriate device. The pitot tube shall be attached to the
probe to allow constant monitoring of the stack gas velocity. The
impact (high pressure) opening plane of the pitot tube shall be
even with or above the nozzle entry plane (see Figure 2-6b, EPA
Method 2, 40 CFR part 60, appendix A) during sampling. The Type S
pitot tube assembly shall have a known coefficient, determined as
outlined in Section 4 of EPA Method 2, 40 CFR part 60, appendix
A.
6.1.4 Differential Pressure Gauge: The differential pressure
gauge shall be an inclined manometer or equivalent device as
described in Section 2.2 of EPA Method 2, 40 CFR part 60, appendix
A. One manometer shall be used for velocity-head reading and the
other for orifice differential pressure readings.
6.1.5 Impingers: The sampling train requires a minimum of four
impingers, connected as shown in Figure 1, with ground glass (or
equivalent) vacuum-tight fittings. For the first, third, and fourth
impingers, use the Greenburg-Smith design, modified by replacing
the tip with a 1.3 cm inside diameters ( 1/2 in) glass tube
extending to 1.3 cm ( 1/2 in) from the bottom of the flask. For the
second impinger, use a Greenburg-Smith impinger with the standard
tip. Place a thermometer capable of measuring temperature to within
1 °C (2 °F) at the outlet of the fourth impinger for monitoring
purposes.
6.1.6 Metering System: The necessary components are a vacuum
gauge, leak-free pump, thermometers capable of measuring
temperatures within 3 °C (5.4 °F), dry-gas meter capable of
measuring volume to within 1 percent, and related equipment as
shown in Figure 1. At a minimum, the pump should be capable of 4
cfm free flow, and the dry gas meter should have a recording
capacity of 0-999.9 cu ft with a resolution of 0.005 cu ft. Other
metering systems may be used which are capable of maintaining
sample volumes to within 2 percent. The metering system may be used
in conjunction with a pitot tube to enable checks of isokinetic
sampling rates.
6.1.7 Barometer: The barometer may be mercury, aneroid, or other
barometer capable of measuring atmospheric pressure to within 2.5
mm Hg (0.1 in Hg). In many cases, the barometric reading may be
obtained from a nearby National Weather Service Station, in which
case the station value (which is the absolute barometric pressure)
is requested and an adjustment for elevation differences between
the weather station and sampling point is applied at a rate of
minus 2.5 mm Hg (0.1 in Hg) per 30 m (100 ft) elevation increase
(rate is plus 2.5 mm Hg per 30 m (100 ft) of elevation
decrease).
6.1.8 Gas Density Determination Equipment: Temperature sensor
and pressure gauge (as described in Sections 2.3 and 2.3 of EPA
Method 2, 40 CFR part 60, appendix A), and gas analyzer, if
necessary (as described in EPA Method 3, 40 CFR part 60, appendix
A). The temperature sensor ideally should be permanently attached
to the pitot tube or sampling probe in a fixed configuration such
that the top of the sensor extends beyond the leading edge of the
probe sheath and does not touch any metal. Alternatively, the
sensor may be attached just prior to use in the field. Note,
however, that if the temperature sensor is attached in the field,
the sensor must be placed in an interference-free arrangement with
respect to the Type S pitot openings (see Figure 2-7, EPA Method 2,
40 CFR part 60, appendix A). As a second alternative, if a
difference of no more than 1 percent in the average velocity
measurement is to be introduced, the temperature gauge need not be
attached to the probe or pitot tube.
6.2 Sample Recovery
6.2.1 Probe Liner: Probe nozzle and brushes; bristle brushes
with stainless steel wire handles are required. The probe brush
shall have extensions of stainless steel, Teflon TM, or inert
material at least as long as the probe. The brushes shall be
properly sized and shaped to brush out the probe liner, the probe
nozzle, and the impingers.
6.2.2 Wash Bottles: One wash bottle is required. Polyethylene,
Teflon TM, or glass wash bottles may be used for sample
recovery.
6.2.3 Graduated Cylinder and/or Balance: A graduated cylinder or
balance is required to measure condensed water to the nearest 1 ml
or 1 g. Graduated cylinders shall have division not >2 ml.
Laboratory balances capable of weighing to ±0.5 g are required.
6.2.4 Polyethylene Storage Containers: 500 ml wide-mouth
polyethylene bottles are required to store impinger water
samples.
6.2.5 Rubber Policeman and Funnel: A rubber policeman and funnel
are required to aid the transfer of material into and out of
containers in the field.
6.3 Sample Analysis
6.3.1 Spectrophotometer - B&L 70, 710, 2000, etc., or
equivalent; 1 cm pathlength cuvette holder.
6.3.2 Disposable polystyrene cuvettes, pathlengh 1 cm, volume of
about 4.5 ml.
6.3.3 Pipettors - Fixed-volume Oxford pipet (250 µl; 500 µl;
1000 µl); adjustable volume Oxford or equivalent pipettor 1-5 ml
model, set to 2.50 ml.
6.3.4 Pipet tips for pipettors above.
6.3.5 Parafilm, 2 ° wide; cut into about 1” squares.
7.0 Reagents
7.1 High purity water: All references to water in this method
refer to high purity water (ASTM Type I water or equivalent). The
water purity will dictate the lower limits of formaldehyde
quantification.
7.2 Silica Gel: Silica gel shall be indicting type, 6-16 mesh.
If the silica gel has been used previously, dry at 175 °C (350 °F)
for 2 hours before using. New silica gel may be used as received.
Alternatively, other types of desiccants (equivalent or better) may
be used.
7.3 Crushed Ice: Quantities ranging from 10-50 lbs may be
necessary during a sampling run, depending upon ambient
temperature. Samples which have been taken must be stored and
shipped cold; sufficient ice for this purpose must be allowed.
7.4 Quaternary ammonium compound stock solution: Prepare a stock
solution of dodecyltrimethylammonium chloride (98 percent minimum
assay, reagent grade) by dissolving 1.0 gram in 1000 ml water. This
solution contains nominally 1000 µg/ml quaternary ammonium
compound, and is used as a biocide for some sources which are prone
to microbial contamination.
7.5 Pararosaniline: Weigh 0.16 grams pararosaniline (free base;
assay of 95 percent or greater, C.I. 42500; Sigma P7632 has been
found to be acceptable) into a 100 ml flask. Exercise care, since
pararosaniline is a dye and will stain. Using a wash bottle with
high-purity water, rinse the walls of the flask. Add no more than
25 ml water. Then, carefully add 20 ml of concentrated hydrochloric
acid to the flask. The flask will become warm after the addition of
acid. Add a magnetic stir bar to the flask, cap, and place on a
magnetic stirrer for approximately 4 hours. Then, add additional
water so the total volume is 100 ml. This solution is stable for
several months when stored tightly capped at room temperature.
7.6 Sodium sulfite: Weigh 0.10 grams anhydrous sodium sulfite
into a 100 ml flask. Dilute to the mark with high purity water.
Invert 15-20 times to mix and dissolve the sodium sulfite. This
solution must be prepared fresh every day.
7.7 Formaldehyde standard solution: Pipet exactly 2.70 ml of 37
percent formaldehyde solution into a 1000 ml volumetric flask which
contains about 500 ml of high-purity water. Dilute to the mark with
high-purity water. This solution contains nominally 1000 µg/ml of
formaldehyde, and is used to prepare the working formaldehyde
standards. The exact formaldehyde concentration may be determined
if needed by suitable modification of the sodium sulfite method
(Reference: J.F. Walker, Formaldehyde (Third Edition), 1964.). The
1000 µg/ml formaldehyde stock solution is stable for at least a
year if kept tightly closed, with the neck of the flask sealed with
Parafilm. Store at room temperature.
7.8 Working formaldehyde standards: Pipet exactly 10.0 ml of the
1000 µg/ml formaldehyde stock solution into a 100 ml volumetric
flask which is about half full of high-purity water. Dilute to the
mark with high-purity water, and invert 15-20 times to mix
thoroughly. This solution contains nominally 100 µg/ml
formaldehyde. Prepare the working standards from this 100 µg/ml
standard solution and using the Oxford pipets:
Working standard, µ/mL |
µL or 100 µg/mL solution |
Volumetric flask volume
(dilute to mark with water) |
0.250 |
250 |
100 |
0.500 |
500 |
100 |
1.00 |
1000 |
100 |
2.00 |
2000 |
100 |
3.00 |
1500 |
50 |
The 100 µg/ml stock solution is stable for 4 weeks if kept
refrigerated between analyses. The working standards (0.25-3.00
µg/ml) should be prepared fresh every day, consistent with good
laboratory practice for trace analysis. If the laboratory water is
not of sufficient purity, it may be necessary to prepare the
working standards every day. The laboratory must establish that the
working standards are stable - DO NOT assume that your working
standards are stable for more than a day unless you have verified
this by actual testing for several series of working standards. 8.0
Sample Collection
8.1 Because of the complexity of this method, field personnel
should be trained in and experienced with the test procedures in
order to obtain reliable results.
8.2 Laboratory Preparation
8.2.1 All the components shall be maintained and calibrated
according to the procedure described in APTD-0576, unless otherwise
specified.
8.2.2 Weigh several 200 to 300 g portions of silica gel in
airtight containers to the nearest 0.5 g. Record on each container
the total weight of the silica gel plus containers. As an
alternative to preweighing the silica gel, it may instead be
weighed directly in the impinger or sampling holder just prior to
train assembly.
8.3 Preliminary Field Determinations
8.3.1 Select the sampling site and the minimum number of
sampling points according to EPA Method 1, 40 CFR part 60, appendix
A, or other relevant criteria. Determine the stack pressure,
temperature, and range of velocity heads using EPA Method 2, 40 CFR
part 60, appendix A. A leak-check of the pitot lines according to
Section 3.1 of EPA Method 2, 40 CFR part 60, appendix A, must be
performed. Determine the stack gas moisture content using EPA
Approximation Method 4,40 CFR part 60, appendix A, or its
alternatives to establish estimates of isokinetic sampling rate
settings. Determine the stack gas dry molecular weight, as
described in EPA Method 2, 40 CFR part 60, appendix A, Section 3.6.
If integrated EPA Method 3, 40 CFR part 60, appendix A, sampling is
used for molecular weight determination, the integrated bag sample
shall be taken simultaneously with, and for the same total length
of time as, the sample run.
8.3.2 Select a nozzle size based on the range of velocity heads
so that it is not necessary to change the nozzle size in order to
maintain isokinetic sampling rates below 28 l/min (1.0 cfm). During
the run do not change the nozzle. Ensure that the proper
differential pressure gauge is chosen for the range of velocity
heads encountered (see Section 2.2 of EPA Method 2, 40 CFR part 60,
appendix A).
8.3.3 Select a suitable probe liner and probe length so that all
traverse points can be sampled. For large stacks, to reduce the
length of the probe, consider sampling from opposite sides of the
stack.
8.3.4 A minimum of 30 cu ft of sample volume is suggested for
emission sources with stack concentrations not greater than
23,000,000 ppbv. Additional sample volume shall be collected as
necessitated by the capacity of the water reagent and analytical
detection limit constraint. Reduced sample volume may be collected
as long as the final concentration of formaldehyde in the stack
sample is greater than 10 (ten) times the detection limit.
8.3.5 Determine the total length of sampling time needed to
obtain the identified minimum volume by comparing the anticipated
average sampling rate with the volume requirement. Allocate the
same time to all traverse points defined by EPA Method 1, 40 CFR
part 60, appendix A. To avoid timekeeping errors, the length of
time sampled at each traverse point should be an integer or an
integer plus 0.5 min.
8.3.6 In some circumstances (e.g., batch cycles) it may be
necessary to sample for shorter times at the traverse points and to
obtain smaller gas-volume samples. In these cases, careful
documentation must be maintained in order to allow accurate
calculations of concentrations.
8.4 Preparation of Collection Train
8.4.1 During preparation and assembly of the sampling train,
keep all openings where contamination can occur covered with Teflon
TM film or aluminum foil until just prior to assembly or until
sampling is about to begin.
8.4.2 Place 100 ml of water in each of the first two impingers,
and leave the third impinger empty. If additional capacity is
required for high expected concentrations of formaldehyde in the
stack gas, 200 ml of water per impinger may be used or additional
impingers may be used for sampling. Transfer approximately 200 to
300 g of pre-weighed silica gel from its container to the fourth
impinger. Care should be taken to ensure that the silica gel is not
entrained and carried out from the impinger during sampling. Place
the silica gel container in a clean place for later use in the
sample recovery. Alternatively, the weight of the silica gel plus
impinger may be determined to the nearest 0.5 g and recorded.
8.4.3 With a glass or quartz liner, install the selected nozzle
using a Viton-A O-ring when stack temperatures are <260 °C (500
°F) and a woven glass-fiber gasket when temperatures are higher.
See APTD-0576 for details. Other connection systems utilizing
either 316 stainless steel or Teflon TM ferrules may be used. Mark
the probe with heat-resistant tape or by some other method to
denote the proper distance into the stack or duct for each sampling
point.
8.4.4 Assemble the train as shown in Figure 1. During assembly,
a very light coating of silicone grease may be used on ground-glass
joints of the impingers, but the silicone grease should be limited
to the outer portion (see APTD-0576) of the ground-glass joints to
minimize silicone grease contamination. If necessary, Teflon TM
tape may be used to seal leaks. Connect all temperature sensors to
an appropriate potentiometer/display unit. Check all temperature
sensors at ambient temperatures.
8.4.5 Place crushed ice all around the impingers.
8.4.6 Turn on and set the probe heating system at the desired
operating temperature. Allow time for the temperature to
stabilize.
8.5 Leak-Check Procedures
8.5.1 Pre-test Leak-check: Recommended, but not required. If the
tester elects to conduct the pre-test leak-check, the following
procedure shall be used.
8.5.1.1 After the sampling train has been assembled, turn on and
set probe heating system at the desired operating temperature.
Allow time for the temperature to stabilize. If a Viton-a O-ring or
other leak-free connection is used in assembling the probe nozzle
to the probe liner, leak-check the train at the sampling site by
plugging the nozzle and pulling a 381 mm Hg (15 in Hg) vacuum.
Note:
A lower vacuum may be used, provided that the lower vacuum is
not exceeded during the test.
If a woven glass fiber gasket is used, do not connect the probe
to the train during the leak-check. Instead, leak-check the train
by first attaching a carbon-filled leak-check impinger to the inlet
and then plugging the inlet and pulling a 381 mm Hg (15 in Hg)
vacuum. (A lower vacuum may be used if this lower vacuum is not
exceeded during the test.) Next connect the probe to the train and
leak-check at about 25 mm Hg (1 in Hg) vacuum. Alternatively,
leak-check the probe with the rest of the sampling train in one
step at 381 mm Hg (15 in Hg) vacuum. Leakage rates in excess of (a)
4 percent of the average sampling rate or (b) 0.00057 m 3/min (0.02
cfm), whichever is less, are unacceptable.
8.5.1.2 The following leak-check instructions for the sampling
train described in APTD-0576 and APTD-0581 may be helpful. Start
the pump with the fine-adjust valve fully open and coarse-valve
completely closed. Partially open the coarse-adjust valve and
slowly close the fine-adjust valve until the desired vacuum is
reached. Do not reverse direction of the fine-adjust valve, as
liquid will back up into the train. If the desired vacuum is
exceeded, either perform the leak-check at this higher vacuum or
end the leak-check, as described below, and start over.
8.5.1.3 When the leak-check is completed, first slowly remove
the plug from the inlet to the probe. When the vacuum drops to 127
mm (5 in) Hg or less, immediately close the coarse-adjust valve.
Switch off the pumping system and reopen the fine-adjust valve. Do
not reopen the fine-adjust valve until the coarse-adjust valve has
been closed to prevent the liquid in the impingers from being
forced backward in the sampling line and silica gel from being
entrained backward into the third impinger.
8.5.2 Leak-checks During Sampling Run:
8.5.2.1 If, during the sampling run, a component change (e.g.,
impinger) becomes necessary, a leak-check shall be conducted
immediately after the interruption of sampling and before the
change is made. The leak-check shall be done according to the
procedure described in Section 10.3.3, except that it shall be done
at a vacuum greater than or equal to the maximum value recorded up
to that point in the test. If the leakage rate is found to be no
greater than 0.0057 m 3/min (0.02 cfm) or 4 percent of the average
sampling rate (whichever is less), the results are acceptable. If a
higher leakage rate is obtained, the tester must void the sampling
run.
Note:
Any correction of the sample volume by calculation reduces the
integrity of the pollutant concentration data generated and must be
avoided.
8.5.2.2 Immediately after component changes, leak-checks are
optional. If performed, the procedure described in section 8.5.1.1
shall be used.
8.5.3 Post-test Leak-check:
8.5.3.1 A leak-check is mandatory at the conclusion of each
sampling run. The leak-check shall be done with the same procedures
as the pre-test leak-check, except that the post-test leak-check
shall be conducted at a vacuum greater than or equal to the maximum
value reached during the sampling run. If the leakage rate is found
to be no greater than 0.00057 m 3/min (0.02 cfm) or 4 percent of
the average sampling rate (whichever is less), the results are
acceptable. If, however, a higher leakage rate is obtained, the
tester shall record the leakage rate and void the sampling run.
8.6 Sampling Train Operation
8.6.1 During the sampling run, maintain an isokinetic sampling
rate to within 10 percent of true isokinetic, below 28 l/min (1.0
cfm). Maintain a temperature around the probe of 120 °C ±14 °C (248
° ±25 °F).
8.6.2 For each run, record the data on a data sheet such as the
one shown in Figure 2. Be sure to record the initial dry-gas meter
reading. Record the dry-gas meter readings at the beginning and end
of each sampling time increment, when changes in flow rates are
made, before and after each leak-check, and when sampling is
halted. Take other readings required by Figure 2 at least once at
each sample point during each time increment and additional
readings when significant adjustments (20 percent variation in
velocity head readings) necessitate additional adjustments in flow
rate. Level and zero the manometer. Because the manometer level and
zero may drift due to vibrations and temperature changes, make
periodic checks during the traverse.
Traverse point
number |
Sampling time
(e) min. |
Vacuum
mm Hg
(in. Hg) |
Stack temperature
(T)
°C (°F) |
Velocity head
(ΔP) mm
(in) H2O |
Pressure
differential across orifice meter
mm H2O
(in. H2O) |
Gas sample
volume
m 3
(ft 3) |
Gas sample
temperature at dry gas meter |
Filter holder
temperature
°C (°F) |
Temperature of
gas leaving condenser or last impinger
°C (°F) |
Inlet
°C (°F) |
Outlet
°C (°F) |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Total |
|
|
|
|
|
|
Avg. |
Avg. |
|
|
Average |
|
|
|
|
|
|
Avg. |
|
|
|
8.6.3 Clean the stack access ports prior to the test run to
eliminate the chance of sampling deposited material. To begin
sampling, remove the nozzle cap, verify that the probe heating
system are at the specified temperature, and verify that the pitot
tube and probe are properly positioned. Position the nozzle at the
first traverse point, with the tip pointing directly into the gas
stream. Immediately start the pump and adjust the flow to
isokinetic conditions. Nomographs, which aid in the rapid
adjustment of the isokinetic sampling rate without excessive
computations, are available. These nomographs are designed for use
when the Type S pitot tube coefficient is 0.84 ±0.02 and the stack
gas equivalent density (dry molecular weight) is equal to 29 ±4.
APTD-0576 details the procedure for using the nomographs. If the
stack gas molecular weight and the pitot tube coefficient are
outside the above ranges, do not use the nomographs unless
appropriate steps are taken to compensate for the deviations.
8.6.4 When the stack is under significant negative pressure
(equivalent to the height of the impinger stem), take care to close
the coarse-adjust valve before inserting the probe into the stack
in order to prevent liquid from backing up through the train. If
necessary, a low vacuum on the train may have to be started prior
to entering the stack.
8.6.5 When the probe is in position, block off the openings
around the probe and stack access port to prevent unrepresentative
dilution of the gas stream.
8.6.6 Traverse the stack cross section, as required by EPA
Method 1, 40 CFR part 60, appendix A, being careful not to bump the
probe nozzle into the stack walls when sampling near the walls or
when removing or inserting the probe through the access port, in
order to minimize the chance of extracting deposited material.
8.6.7 During the test run, make periodic adjustments to keep the
temperature around the probe at the proper levels. Add more ice
and, if necessary, salt, to maintain a temperature of <20 °C (68
°F) at the silica gel outlet.
8.6.8 A single train shall be used for the entire sampling run,
except in cases where simultaneous sampling is required in two or
more separate ducts or at two or more different locations within
the same duct, or in cases where equipment failure necessitates a
change of trains. An additional train or trains may also be used
for sampling when the capacity of a single train is exceeded.
8.6.9 When two or more trains are used, separate analyses of
components from each train shall be performed. If multiple trains
have been used because the capacity of a single train would be
exceeded, first impingers from each train may be combined, and
second impingers from each train may be combined.
8.6.10 At the end of the sampling run, turn off the
coarse-adjust valve, remove the probe and nozzle from the stack,
turn off the pump, record the final dry gas meter reading, and
conduct a post-test leak-check. Also, check the pitot lines as
described in EPA Method 2, 40 CFR part 60, appendix A. The lines
must pass this leak-check in order to validate the velocity-head
data.
8.6.11 Calculate percent isokineticity (see Method 2) to
determine whether the run was valid or another test should be
made.
8.7 Sample Preservation and Handling
8.7.1 Samples from most sources applicable to this method have
acceptable holding times using normal handling practices (shipping
samples iced, storing in refrigerator at 2 °C until analysis).
However, forming section stacks and other sources using waste water
sprays may be subject to microbial contamination. For these
sources, a biocide (quaternary ammonium compound solution) may be
added to collected samples to improve sample stability and method
ruggedness.
8.7.2 Sample holding time: Samples should be analyzed within 14
days of collection. Samples must be refrigerated/kept cold for the
entire period preceding analysis. After the samples have been
brought to room temperature for analysis, any analyses needed
should be performed on the same day. Repeated cycles of warming the
samples to room temperature/refrigerating/rewarming, then analyzing
again, etc., have not been investigated in depth to evaluate if
analyte levels remain stable for all sources.
8.7.3 Additional studies will be performed to evaluate whether
longer sample holding times are feasible for this method.
8.8 Sample Recovery
8.8.1 Preparation:
8.8.1.1 Proper cleanup procedure begins as soon as the probe is
removed from the stack at the end of the sampling period. Allow the
probe to cool. When the probe can be handled safely, wipe off all
external particulate matter near the tip of the probe nozzle and
place a cap over the tip to prevent losing or gaining particulate
matter. Do not cap the probe tightly while the sampling train is
cooling because a vacuum will be created, drawing liquid from the
impingers back through the sampling train.
8.8.1.2 Before moving the sampling train to the cleanup site,
remove the probe from the sampling train and cap the open outlet,
being careful not to lose any condensate that might be present.
Remove the umbilical cord from the last impinger and cap the
impinger. If a flexible line is used, let any condensed water or
liquid drain into the impingers. Cap off any open impinger inlets
and outlets. Ground glass stoppers, Teflon TM caps, or caps of
other inert materials may be used to seal all openings.
8.8.1.3 Transfer the probe and impinger assembly to an area that
is clean and protected from wind so that the chances of
contaminating or losing the sample are minimized.
8.8.1.4 Inspect the train before and during disassembly, and
note any abnormal conditions.
8.8.1.5 Save a portion of the washing solution (high purity
water) used for cleanup as a blank.
8.8.2 Sample Containers:
8.8.2.1 Container 1: Probe and Impinger Catches. Using a
graduated cylinder, measure to the nearest ml, and record the
volume of the solution in the first three impingers. Alternatively,
the solution may be weighed to the nearest 0.5 g. Include any
condensate in the probe in this determination. Transfer the
combined impinger solution from the graduated cylinder into the
polyethylene bottle. Taking care that dust on the outside of the
probe or other exterior surfaces does not get into the sample,
clean all surfaces to which the sample is exposed (including the
probe nozzle, probe fitting, probe liner, first three impingers,
and impinger connectors) with water. Use less than 400 ml for the
entire waste (250 ml would be better, if possible). Add the rinse
water to the sample container.
8.8.2.1.1 Carefully remove the probe nozzle and rinse the inside
surface with water from a wash bottle. Brush with a bristle brush
and rinse until the rinse shows no visible particles, after which
make a final rinse of the inside surface. Brush and rinse the
inside parts of the Swagelok (or equivalent) fitting with water in
a similar way.
8.8.2.1.2 Rinse the probe liner with water. While squirting the
water into the upper end of the probe, tilt and rotate the probe so
that all inside surfaces will be wetted with water. Let the water
drain from the lower end into the sample container. The tester may
use a funnel (glass or polyethylene) to aid in transferring the
liquid washes to the container. Follow the rinse with a bristle
brush. Hold the probe in an inclined position, and squirt water
into the upper end as the probe brush is being pushed with a
twisting action through the probe. Hold the sample container
underneath the lower end of the probe, and catch any water and
particulate matter that is brushed from the probe. Run the brush
through the probe three times or more. Rinse the brush with water
and quantitatively collect these washings in the sample container.
After the brushing, make a final rinse of the probe as describe
above.
Note:
Two people should clean the probe in order to minimize sample
losses. Between sampling runs, brushes must be kept clean and free
from contamination.
8.8.2.1.3 Rinse the inside surface of each of the first three
impingers (and connecting tubing) three separate times. Use a small
portion of water for each rinse, and brush each surface to which
the sample is exposed with a bristle brush to ensure recovery of
fine particulate matter. Make a final rinse of each surface and of
the brush, using water.
8.8.2.1.4 After all water washing and particulate matter have
been collected in the sample container, tighten the lid so the
sample will not leak out when the container is shipped to the
laboratory. Mark the height of the fluid level to determine whether
leakage occurs during transport. Label the container clearly to
identify its contents.
8.8.2.1.5 If the first two impingers are to be analyzed
separately to check for breakthrough, separate the contents and
rinses of the two impingers into individual containers. Care must
be taken to avoid physical carryover from the first impinger to the
second. Any physical carryover of collected moisture into the
second impinger will invalidate a breakthrough assessment.
8.8.2.2 Container 2: Sample Blank. Prepare a blank by using a
polyethylene container and adding a volume of water equal to the
total volume in Container 1. Process the blank in the same manner
as Container 1.
8.8.2.3 Container 3: Silica Gel. Note the color of the
indicating silica gel to determine whether it has been completely
spent and make a notation of its condition. The impinger containing
the silica gel may be used as a sample transport container with
both ends sealed with tightly fitting caps or plugs. Ground-glass
stoppers or Teflon TM caps maybe used. The silica gel impinger
should then be labeled, covered with aluminum foil, and packaged on
ice for transport to the laboratory. If the silica gel is removed
from the impinger, the tester may use a funnel to pour the silica
gel and a rubber policeman to remove the silica gel from the
impinger. It is not necessary to remove the small amount of dust
particles that may adhere to the impinger wall and are difficult to
remove. Since the gain in weight is to be used for moisture
calculations, do not use water or other liquids to transfer the
silica gel. If a balance is available in the field, the spent
silica gel (or silica gel plus impinger) may be weighed to the
nearest 0.5 g.
8.8.2.4 Sample containers should be placed in a cooler, cooled
by (although not in contact with) ice. Putting sample bottles in
Zip-Lock TM bags can aid in maintaining the integrity of the sample
labels. Sample containers should be placed vertically to avoid
leakage during shipment. Samples should be cooled during shipment
so they will be received cold at the laboratory. It is critical
that samples be chilled immediately after recovery. If the source
is susceptible to microbial contamination from wash water (e.g.
forming section stack), add biocide as directed in section
8.2.5.
8.8.2.5 A quaternary ammonium compound can be used as a biocide
to stabilize samples against microbial degradation following
collection. Using the stock quaternary ammonium compound (QAC)
solution; add 2.5 ml QAC solution for every 100 ml of recovered
sample volume (estimate of volume is satisfactory) immediately
after collection. The total volume of QAC solution must be
accurately known and recorded, to correct for any dilution caused
by the QAC solution addition.
8.8.3 Sample Preparation for Analysis 8.8.3.1 The sample should
be refrigerated if the analysis will not be performed on the day of
sampling. Allow the sample to warm at room temperature for about
two hours (if it has been refrigerated) prior to analyzing.
8.8.3.2 Analyze the sample by the pararosaniline method, as
described in Section 11. If the color-developed sample has an
absorbance above the highest standard, a suitable dilution in high
purity water should be prepared and analyzed.
9.0 Quality Control
9.1 Sampling: See EPA Manual 600/4-77-02b for Method 5 quality
control.
9.2 Analysis: The quality assurance program required for this
method includes the analysis of the field and method blanks, and
procedure validations. The positive identification and quantitation
of formaldehyde are dependent on the integrity of the samples
received and the precision and accuracy of the analytical
methodology. Quality assurance procedures for this method are
designed to monitor the performance of the analytical methodology
and to provide the required information to take corrective action
if problems are observed in laboratory operations or in field
sampling activities.
9.2.1 Field Blanks: Field blanks must be submitted with the
samples collected at each sampling site. The field blanks include
the sample bottles containing aliquots of sample recover water, and
water reagent. At a minimum, one complete sampling train will be
assembled in the field staging area, taken to the sampling area,
and leak-checked at the beginning and end of the testing (or for
the same total number of times as the actual sampling train). The
probe of the blank train must be heated during the sample test. The
train will be recovered as if it were an actual test sample. No
gaseous sample will be passed through the blank sampling train.
9.2.2 Blank Correction: The field blank formaldehyde
concentrations will be subtracted from the appropriate sample
formaldehyde concentrations. Blank formaldehyde concentrations
above 0.25 µg/ml should be considered suspect, and subtraction from
the sample formaldehyde concentrations should be performed in a
manner acceptable to the Administrator.
9.2.3 Method Blanks: A method blank must be prepared for each
set of analytical operations, to evaluate contamination and
artifacts that can be derived from glassware, reagents, and sample
handling in the laboratory.
10 Calibration
10.1 Probe Nozzle: Probe nozzles shall be calibrated before
their initial use in the field. Using a micrometer, measure the
inside diameter of the nozzle to the nearest 0.025 mm (0.001 in).
Make measurements at three separate places across the diameter and
obtain the average of the measurements. The difference between the
high and low numbers shall not exceed 0.1 mm (0.004 in). When the
nozzle becomes nicked or corroded, it shall be repaired and
calibrated, or replaced with a calibrated nozzle before use. Each
nozzle must be permanently and uniquely identified.
10.2 Pitot Tube: The Type S pitot tube assembly shall be
calibrated according to the procedure outlined in Section 4 of EPA
Method 2, or assigned a nominal coefficient of 0.84 if it is not
visibly nicked or corroded and if it meets design and
intercomponent spacing specifications.
10.3 Metering System
10.3.1 Before its initial use in the field, the metering system
shall be calibrated according to the procedure outlined in
APTD-0576. Instead of physically adjusting the dry-gas meter dial
readings to correspond to the wet-test meter readings, calibration
factors may be used to correct the gas meter dial readings
mathematically to the proper values. Before calibrating the
metering system, it is suggested that a leak-check be conducted.
For metering systems having diaphragm pumps, the normal leak-check
procedure will not delete leakages with the pump. For these cases,
the following leak-check procedure will apply: Make a ten-minute
calibration run at 0.00057 m 3/min (0.02 cfm). At the end of the
run, take the difference of the measured wet-test and dry-gas meter
volumes and divide the difference by 10 to get the leak rate. The
leak rate should not exceed 0.00057 m 3/min (0.02 cfm).
10.3.2 After each field use, check the calibration of the
metering system by performing three calibration runs at a single
intermediate orifice setting (based on the previous field test).
Set the vacuum at the maximum value reached during the test series.
To adjust the vacuum, insert a valve between the wet-test meter and
the inlet of the metering system. Calculate the average value of
the calibration factor. If the calibration has changed by more than
5 percent, recalibrate the meter over the full range of orifice
settings, as outlined in APTD-0576.
10.3.3 Leak-check of metering system: The portion of the
sampling train from the pump to the orifice meter (see Figure 1)
should be leak-checked prior to initial use and after each
shipment. Leakage after the pump will result in less volume being
recorded than is actually sampled. Use the following procedure:
Close the main valve on the meter box. Insert a one-hole rubber
stopper with rubber tubing attached into the orifice exhaust pipe.
Disconnect and vent the low side of the orifice manometer. Close
off the low side orifice tap. Pressurize the system to 13-18 cm
(5-7 in) water column by blowing into the rubber tubing. Pinch off
the tubing and observe the manometer for 1 min. A loss of pressure
on the manometer indicates a leak in the meter box. Leaks must be
corrected.
Note:
If the dry-gas meter coefficient values obtained before and
after a test series differ by >5 percent, either the test series
must be voided or calculations for test series must be performed
using whichever meter coefficient value (i.e., before or after)
gives the lower value of total sample volume.
10.4 Probe Heater: The probe heating system must be calibrated
before its initial use in the field according to the procedure
outlined in APTD-0576. Probes constructed according to APTD-0581
need not be calibrated if the calibration curves in APTD-0576 are
used.
10.5 Temperature gauges: Use the procedure in Section 4.3 of EPA
Method 2 to calibrate in-stack temperature gauges. Dial
thermometers, such as are used for the dry gas meter and condenser
outlet, shall be calibrated against mercury-in-glass thermometers.
An alternative mercury-free thermometer may be used if the
thermometer is, at a minimum, equivalent in terms of performance or
suitably effective for the specific temperature measurement
application.
10.6 Barometer: Adjust the barometer initially and before each
test series to agree to within ±2.5 mm Hg (0.1 in Hg) of the
mercury barometer. Alternately, if a National Weather Service
Station (NWSS) is located at the same altitude above sea level as
the test site, the barometric pressure reported by the NWSS may be
used.
10.7 Balance: Calibrate the balance before each test series,
using Class S standard weights. The weights must be within ±0.5
percent of the standards, or the balance must be adjusted to meet
these limits.
11.0 Procedure for Analysis
The working formaldehyde standards (0.25, 0.50, 1.0, 2.0, and
3.0 µg/ml) are analyzed and a calibration curve is calculated for
each day's analysis. The standards should be analyzed first to
ensure that the method is working properly prior to analyzing the
samples. In addition, a sample of the high-purity water should also
be analyzed and used as a “0” formaldehyde standard.
The procedure for analysis of samples and standards is
identical: Using the pipet set to 2.50 ml, pipet 2.50 ml of the
solution to be analyzed into a polystyrene cuvette. Using the 250
µl pipet, pipet 250 µl of the pararosaniline reagent solution into
the cuvette. Seal the top of the cuvette with a Parafilm square and
shake at least 30 seconds to ensure the solution in the cuvette is
well-mixed. Peel back a corner of the Parafilm so the next reagent
can be added. Using the 250 µl pipet, pipet 250 µl of the sodium
sulfite reagent solution into the cuvette. Reseal the cuvette with
the Parafilm, and again shake for about 30 seconds to mix the
solution in the cuvette. Record the time of addition of the sodium
sulfite and let the color develop at room temperature for 60
minutes. Set the spectrophotometer to 570 nm and set to read in
Absorbance Units. The spectrophotometer should be equipped with a
holder for the 1-cm pathlength cuvettes. Place cuvette(s)
containing high-purity water in the spectrophotometer and adjust to
read 0.000 AU.
After the 60 minutes color development period, read the standard
and samples in the spectrophotometer. Record the absorbance reading
for each cuvette. The calibration curve is calculated by linear
regression, with the formaldehyde concentration as the “x”
coordinate of the pair, and the absorbance reading as the “y”
coordinate. The procedure is very reproducible, and typically will
yield values similar to these for the calibration curve:
Correlation Coefficient: 0.9999 Slope: 0.50 Y-Intercept: 0.090 The
formaldehyde concentration of the samples can be found by using the
trend-line feature of the calculator or computer program used for
the linear regression. For example, the TI-55 calculators use the
“X” key (this gives the predicted formaldehyde concentration for
the value of the absorbance you key in for the sample). Multiply
the formaldehyde concentration from the sample by the dilution
factor, if any, for the sample to give the formaldehyde
concentration of the original, undiluted, sample (units will be
micrograms/ml).
11.1 Notes on the Pararosaniline Procedure
11.1.1 The pararosaniline method is temperature-sensitive.
However, the small fluctuations typical of a laboratory will not
significantly affect the results.
11.1.2 The calibration curve is linear to beyond 4 “µg/ml”
formaldehyde, however, a research-grade spectrophotometer is
required to reproducibly read the high absorbance values. Consult
your instrument manual to evaluate the capability of the
spectrophotometer.
11.1.3 The quality of the laboratory water used to prepare
standards and make dilutions is critical. It is important that the
cautions given in the Reagents section be observed. This procedure
allows quantitation of formaldehyde at very low levels, and thus it
is imperative to avoid contamination from other sources of
formaldehyde and to exercise the degree of care required for trace
analyses.
11.1.4 The analyst should become familiar with the operation of
the Oxford or equivalent pipettors before using them for an
analysis. Follow the instructions of the manufacturer; one can
pipet water into a tared container on any analytical balance to
check pipet accuracy and precision. This will also establish if the
proper technique is being used. Always use a new tip for each
pipetting operation.
11.1.5 This procedure follows the recommendations of ASTM
Standard Guide D 3614, reading all solutions versus water in the
reference cell. This allows the absorbance of the blank to be
tracked on a daily basis. Refer to ASTM D 3614 for more
information.
12.0 Calculations
Carry out calculations, retaining at least one extra decimal
figure beyond that of the acquired data. Round off figures after
final calculations.
12.1 Calculations of Total Formaldehyde
12.1.1 To determine the total formaldehyde in mg, use the
following equation if biocide was not used:
Total mg formaldehyde=

Where: Cd
= measured conc. formaldehyde, µg/ml V = total volume of stack
sample, ml DF = dilution factor
12.1.2 To determine the total formaldehyde in mg, use the
following equation if biocide was used:
Total mg formaldehyde=

Where: Cd
= measured conc. formaldehyde, µg/ml V = total volume of stack
sample, ml B = total volume of biocide added to sample, ml DF =
dilution factor
12.2 Formaldehyde concentration (mg/m 3) in stack gas. Determine
the formaldehyde concentration (mg/m 3) in the stack gas using the
following equation: Formaldehyde concentration (mg/m 3) =

Where: K
= 35.31 cu ft/m 3 for Vm (std) in English units, or K = 1.00 m 3/m
3 for Vm (std) in metric units Vm (std) = volume of gas sample
measured by a dry gas meter, corrected to standard conditions, dscm
(dscf)
12.3 Average dry gas meter temperature and average orifice
pressure drop are obtained from the data sheet.
12.4 Dry Gas Volume: Calculate Vm (std) and adjust for leakage,
if necessary, using the equation in Section 6.3 of EPA Method 5, 40
CFR part 60, appendix A.
12.5 Volume of Water Vapor and Moisture Content: Calculated the
volume of water vapor and moisture content from equations 5-2 and
5-3 of EPA Method 5.
13.0 Method Performance
The precision of this method is estimated to be better than ±5
percent, expressed as ±the percent relative standard deviation.
14.0 Pollution Prevention [Reserved] 15.0 Waste Management
[Reserved] 16.0 References R.R. Miksch, et al., Analytical
Chemistry, November 1981, 53 pp. 2118-2123. J.F. Walker,
Formaldehyde, Third Edition, 1964. US EPA 40 CFR, part 60, Appendix
A, Test Methods 1-5 Method 318 - Extractive FTIR Method for the
Measurement of Emissions From the Mineral Wool and Wool Fiberglass
Industries 1.0 Scope and Application
This method has been validated and approved for mineral wool and
wool fiberglass sources. This method may not be applied to other
source categories without validation and approval by the
Administrator according to the procedures in Test Method 301, 40
CFR part 63, appendix A. For sources seeking to apply FTIR to other
source categories, Test Method 320 (40 CFR part 63, appendix A) may
be utilized.
1.1 Scope. The analytes measured by this method and their CAS
numbers are:
Carbon Monoxide 630-08-0 Carbonyl Sulfide 463-58-1 Formaldehyde
50-00-0 Methanol 1455-13-6 Phenol 108-95-2
1.2 Applicability
1.2.1 This method is applicable for the determination of
formaldehyde, phenol, methanol, carbonyl sulfide (COS) and carbon
monoxide (CO) concentrations in controlled and uncontrolled
emissions from manufacturing processes using phenolic resins. The
compounds are analyzed in the mid-infrared spectral region (about
400 to 4000 cm−1 or 25 to 2.5 µm). Suggested analytical regions are
given below (Table 1). Slight deviations from these recommended
regions may be necessary due to variations in moisture content and
ammonia concentration from source to source.
Table 1 - Example Analytical Regions
Compound |
Analytical region (cm−1)
FLm − FUm |
Potential interferants |
Formaldehyde |
2840.93−2679.83 |
Water, Methane. |
Phenol |
1231.32−1131.47 |
Water, Ammonia, Methane. |
Methanol |
1041.56−1019.95 |
Water, Ammonia. |
COS
a |
2028.4−2091.9 |
Water, CO2 CO. |
CO
a |
2092.1−2191.8 |
Water, CO2, COS. |
1.2.2 This method does not apply when: (a) Polymerization of
formaldehyde occurs, (b) moisture condenses in either the sampling
system or the instrumentation, and (c) when moisture content of the
gas stream is so high relative to the analyte concentrations that
it causes severe spectral interference.
1.3 Method Range and Sensitivity
1.3.1 The analytical range is a function of instrumental design
and composition of the gas stream. Theoretical detection limits
depend, in part, on (a) the absorption coefficient of the compound
in the analytical frequency region, (b) the spectral resolution,
(c) interferometer sampling time, (d) detector sensitivity and
response, and (e) absorption pathlength.
1.3.2 Practically, there is no upper limit to the range. The
practical lower detection limit is usually higher than the
theoretical value, and depends on (a) moisture content of the flue
gas, (b) presence of interferants, and (c) losses in the sampling
system. In general, a 22 meter pathlength cell in a suitable
sampling system can achieve practical detection limits of 1.5 ppm
for three compounds (formaldehyde, phenol, and methanol) at
moisture levels up to 15 percent by volume. Sources with
uncontrolled emissions of CO and COS may require a 4 meter
pathlength cell due to high concentration levels. For these two
compounds, make sure absorbance of highest concentration component
is <1.0.
1.4 Data Quality Objectives
1.4.1 In designing or configuring the system, the analyst first
sets the data quality objectives, i.e., the desired lower detection
limit (DLi) and the desired analytical uncertainty (AUi) for each
compound. The instrumental parameters (factors b, c, d, and e in
Section 1.3.1) are then chosen to meet these requirements, using
Appendix D of the FTIR Protocol. 1.4.2 Data quality for each
application is determined, in part, by measuring the RMS (Root Mean
Square) noise level in each analytical spectral region (Appendix C
of the FTIR Protocol). The RMS noise is defined as the RMSD (Root
Mean Square Deviation) of the absorbance values in an analytical
region from the mean absorbance value of the region. Appendix D of
the FTIR Protocol defines the MAUim (minimum analyte uncertainty of
the i th analyte in the m th analytical region). The MAU is the
minimum analyte concentration for which the analytical uncertainty
limit (AUi) can be maintained: if the measured analyte
concentration is less than MAUi, then data quality is unacceptable.
Table 2 gives some example DL and AU values along with calculated
areas and MAU values using the protocol procedures.
Table 2 - Example Pre-Test Protocol
Calculations
Protocol value |
Form |
Phenol |
Methanol |
Protocol
appendix |
Reference
concentration a (ppm-meters)/K |
3.016 |
3.017 |
5.064 |
|
Reference Band
Area |
8.2544 |
16.6417 |
4.9416 |
B |
DL
(ppm-meters)/K |
0.1117 |
0.1117 |
0.1117 |
B |
AU |
0.2 |
0.2 |
0.2 |
B |
CL |
0.02234 |
0.02234 |
0.02234 |
B |
FL |
2679.83 |
1131.47 |
1019.95 |
B |
FU |
2840.93 |
1231.32 |
1041.56 |
B |
FC |
2760.38 |
1181.395 |
1030.755 |
B |
AAI
(ppm-meters)/K |
0.18440 |
0.01201 |
0.00132 |
B |
RMSD |
2.28E-03 |
1.21E-03 |
1.07E-03 |
C |
MAU
(ppm-meters)/K |
4.45E-02 |
7.26E-03 |
4.68E-03 |
D |
MAU (ppm at
22) |
0.0797 |
0.0130 |
0.0084 |
D |
2.0 Summary of Method
2.1 Principle
2.1.1 Molecules are composed of chemically bonded atoms, which
are in constant motion. The atomic motions result in bond
deformations (bond stretching and bond-angle bending). The number
of fundamental (or independent) vibrational motions depends on the
number of atoms (N) in the molecule. At typical testing
temperatures, most molecules are in the ground-state vibrational
state for most of their fundamental vibrational motions. A molecule
can undergo a transition from its ground state (for a particular
vibration) to the first excited state by absorbing a quantum of
light at a frequency characteristic of the molecule and the
molecular motion. Molecules also undergo rotational transitions by
absorbing energies in the far-infrared or microwave spectral
regions. Rotational transition absorbencies are superimposed on the
vibrational absorbencies to give a characteristic shape to each
rotational-vibrational absorbance “band.”
2.1.2 Most molecules exhibit more than one absorbance band in
several frequency regions to produce an infrared spectrum (a
characteristic pattern of bands or a “fingerprint”) that is unique
to each molecule. The infrared spectrum of a molecule depends on
its structure (bond lengths, bond angles, bond strengths, and
atomic masses). Even small differences in structure can produce
significantly different spectra.
2.1.3 Spectral band intensities vary with the concentration of
the absorbing compound. Within constraints, the relationship
between absorbance and sample concentration is linear. Sample
spectra are compared to reference spectra to determine the species
and their concentrations.
2.2 Sampling and Analysis
2.2.1 Flue gas is continuously extracted from the source, and
the gas or a portion of the gas is conveyed to the FTIR gas cell,
where a spectrum of the flue gas is recorded. Absorbance band
intensities are related to sample concentrations by Beer's Law.

Where: An
= absorbance of the i th component at the given frequency, ν. a =
absorption coefficient of the i th component at the frequency, ν. b
= path length of the cell. c = concentration of the i th compound
in the sample at frequency ν.
2.2.2 After identifying a compound from the infrared spectrum,
its concentration is determined by comparing band intensities in
the sample spectrum to band intensities in “reference spectra” of
the formaldehyde, phenol, methanol, COS and CO. These reference
spectra are available in a permanent soft copy from the EPA
spectral library on the EMTIC bulletin board. The source may also
prepare reference spectra according to Section 4.5 of the FTIR
Protocol.
Note:
Reference spectra not prepared according to the FTIR Protocol
are not acceptable for use in this test method. Documentation
detailing the FTIR Protocol steps used in preparing any non-EPA
reference spectra shall be included in each test report submitted
by the source.
2.3 Operator Requirements. The analyst must have some knowledge
of source sampling and of infrared spectral patterns to operate the
sampling system and to choose a suitable instrument configuration.
The analyst should also understand FTIR instrument operation well
enough to choose an instrument configuration consistent with the
data quality objectives.
3.0 Definitions
See Appendix A of the FTIR Protocol.
4.0 Interferences
4.1 Analytical (or Spectral) Interferences. Water vapor. High
concentrations of ammonia (hundreds of ppm) may interfere with the
analysis of low concentrations of methanol (1 to 5 ppm). For CO,
carbon dioxide and water may be interferants. In cases where COS
levels are low relative to CO levels, CO and water may be
interferants.
4.2 Sampling System Interferences. Water, if it condenses, and
ammonia, which reacts with formaldehyde.
5.0 Safety
5.1 Formaldehyde is a suspected carcinogen; therefore, exposure
to this compound must be limited. Proper monitoring and safety
precautions must be practiced in any atmosphere with potentially
high concentrations of CO.
5.2 This method may involve sampling at locations having high
positive or negative pressures, high temperatures, elevated
heights, high concentrations of hazardous or toxic pollutants, or
other diverse sampling conditions. It is the responsibility of the
tester(s) to ensure proper safety and health practices, and to
determine the applicability of regulatory limitations before
performing this test method.
6.0 Equipment and Supplies
The equipment and supplies are based on the schematic of a
sampling train shown in Figure 1. Either the evacuated or purged
sampling technique may be used with this sampling train.
Alternatives may be used, provided that the data quality objectives
of this method are met.
6.1 Sampling Probe. Glass, stainless steel, or other appropriate
material of sufficient length and physical integrity to sustain
heating, prevent adsorption of analytes, and to reach gas sampling
point.
6.2 Particulate Filters. A glass wool plug (optional) inserted
at the probe tip (for large particulate removal) and a filter rated
at 1-micron (e.g., Balston TM) for fine particulate removal, placed
immediately after the heated probe.
6.3 Sampling Line/Heating System. Heated (maintained at 250 ±25
degrees F) stainless steel, Teflon TM, or other inert material that
does not adsorb the analytes, to transport the sample to analytical
system.
6.4 Stainless Steel Tubing. Type 316, e.g., 3/8 in. diameter,
and appropriate length for heated connections.
6.5 Gas Regulators. Appropriate for individual gas
cylinders.
6.6 Teflon TM Tubing. Diameter (e.g., 3/8 in.) and length
suitable to connect cylinder regulators.
6.7 Sample Pump. A leak-free pump (e.g., KNF TM), with by-pass
valve, capable of pulling sample through entire sampling system at
a rate of about 10 to 20 L/min. If placed before the analytical
system, heat the pump and use a pump fabricated from materials
non-reactive to the target pollutants. If the pump is located after
the instrument, systematically record the sample pressure in the
gas cell.
6.8 Gas Sample Manifold. A heated manifold that diverts part of
the sample stream to the analyzer, and the rest to the by-pass
discharge vent or other analytical instrumentation.
6.9 Rotameter. A calibrated 0 to 20 L/min range rotameter.
6.10 FTIR Analytical System. Spectrometer and detector, capable
of measuring formaldehyde, phenol, methanol, COS and CO to the
predetermined minimum detectable level. The system shall include a
personal computer with compatible software that provides real-time
updates of the spectral profile during sample collection and
spectral collection.
6.11 FTIR Cell Pump. Required for the evacuated sampling
technique, capable of evacuating the FTIR cell volume within 2
minutes. The FTIR cell pump should allow the operator to obtain at
least 8 sample spectra in 1 hour.
6.12 Absolute Pressure Gauge. Heatable and capable of measuring
pressure from 0 to 1000 mmHg to within ±2.5 mmHg (e.g., Baratron
TM).
6.13 Temperature Gauge. Capable of measuring the cell
temperature to within ±2 °C.
7.0 Reagents and Standards
7.1 Ethylene (Calibration Transfer Standard). Obtain NIST
traceable (or Protocol) cylinder gas.
7.2 Nitrogen. Ultra high purity (UHP) grade.
7.3 Reference Spectra. Obtain reference spectra for the target
pollutants at concentrations that bracket (in ppm-meter/K) the
emission source levels. Also, obtain reference spectra for SF6 and
ethylene. Suitable concentrations are 0.0112 to 0.112 (ppm-meter)/K
for SF6 and 5.61 (ppm-meter)/K or less for ethylene. The reference
spectra shall meet the criteria for acceptance outlined in Section
2.2.2. The optical density (ppm-meters/K) of the reference spectrum
must match the optical density of the sample spectrum within (less
than) 25 percent.
8.0 Sample Collection, Preservation, and Storage
Sampling should be performed in the following sequence: Collect
background, collect CTS spectrum, collect samples, collect
post-test CTS spectrum, verify that two copies of all data were
stored on separate computer media.
8.1 Pretest Preparations and Evaluations. Using the procedure in
Section 4.0 of the FTIR Protocol, determine the optimum
sampling system configuration for sampling the target pollutants.
Table 2 gives some example values for AU, DL, and MAU. Based on a
study (Reference 1), an FTIR system using 1 cm−1 resolution, 22
meter path length, and a broad band MCT detector was suitable for
meeting the requirements in Table 2. Other factors that must be
determined are:
a. Test requirements: AUi, CMAXi, DLi, OFUi, and tAN for
each.
b. Interferants: See Table 1.
c. Sampling system: LS′, Pmin, PS′, TS′, tSS, VSS; fractional
error, MIL.
d. Analytical regions: 1 through Nm, FLm, FCm, and FUm, plus
interferants, FFUm, FFLm, wavenumber range FNU to FNL. See Tables 1
and 2.
8.1.1 If necessary, sample and acquire an initial spectrum. Then
determine the proper operational pathlength of the instrument to
obtain non-saturated absorbances of the target analytes.
8.1.2 Set up the sampling train as shown in Figure 1.
8.2 Sampling System Leak-check. Leak-check from the probe tip to
pump outlet as follows: Connect a 0- to 250-mL/min rate meter
(rotameter or bubble meter) to the outlet of the pump. Close off
the inlet to the probe, and note the leakage rate. The leakage rate
shall be ≤200 mL/min.
8.3 Analytical System Leak-check.
8.3.1 For the evacuated sample technique, close the valve to the
FTIR cell, and evacuate the absorption cell to the minimum absolute
pressure Pmin. Close the valve to the pump, and determine the
change in pressure ΔPv after 2 minutes.
8.3.2 For both the evacuated sample and purging techniques,
pressurize the system to about 100 mmHg above atmospheric pressure.
Isolate the pump and determine the change in pressure ΔPp after 2
minutes.
8.3.3 Measure the barometric pressure, Pb in mmHg.
8.3.4 Determine the percent leak volume %VL for the signal
integration time tSS and for ΔPmax, i.e., the larger of ΔPv or ΔPp,
as follows:

Where: 50
= 100% divided by the leak-check time of 2 minutes.
8.3.5 Leak volumes in excess of 4 percent of the sample system
volume VSS are unacceptable.
8.4 Background Spectrum. Evacuate the gas cell to ≤5 mmHg, and
fill with dry nitrogen gas to ambient pressure. Verify that no
significant amounts of absorbing species (for example water vapor
and CO2) are present. Collect a background spectrum, using a signal
averaging period equal to or greater than the averaging period for
the sample spectra. Assign a unique file name to the background
spectrum. Store the spectra of the background interferogram and
processed single-beam background spectrum on two separate computer
media (one is used as the back-up). If continuous sampling will be
used during sample collection, collect the background spectrum with
nitrogen gas flowing through the cell at the same pressure and
temperature as will be used during sampling.
8.5 Pre-Test Calibration Transfer Standard. Evacuate the gas
cell to ≤5 mmHg absolute pressure, and fill the FTIR cell to
atmospheric pressure with the CTS gas. Or, purge the cell with 10
cell volumes of CTS gas. Record the spectrum. If continuous
sampling will be used during sample collection, collect the CTS
spectrum with CTS gas flowing through the cell at the same pressure
and temperature as will be used during sampling.
8.6 Samples
8.6.1 Evacuated Samples. Evacuate the absorbance cell to ≤5 mmHg
absolute pressure. Fill the cell with flue gas to ambient pressure
and record the spectrum. Before taking the next sample, evacuate
the cell until no further evidence of absorption exists. Repeat
this procedure to collect at least 8 separate spectra (samples) in
1 hour.
8.6.2 Purge Sampling. Purge the FTIR cell with 10 cell volumes
of flue gas and at least for about 10 minutes. Discontinue the gas
cell purge, isolate the cell, and record the sample spectrum and
the pressure. Before taking the next sample, purge the cell with 10
cell volumes of flue gas.
8.6.3 Continuous Sampling. Spectra can be collected continuously
while the FTIR cell is being purged. The sample integration time,
tss, the sample flow rate through the FTIR gas cell, and the total
run time must be chosen so that the collected data consist of at
least 10 spectra with each spectrum being of a separate cell volume
of flue gas. More spectra can be collected over the run time and
the total run time (and number of spectra) can be extended as
well.
8.7 Sampling QA, Data Storage and Reporting
8.7.1 Sample integration times should be sufficient to achieve
the required signal-to-noise ratios. Obtain an absorbance spectrum
by filling the cell with nitrogen. Measure the RMSD in each
analytical region in this absorbance spectrum. Verify that the
number of scans is sufficient to achieve the target MAU (Table
2).
8.7.2 Identify all sample spectra with unique file names.
8.7.3 Store on two separate computer media a copy of sample
interferograms and processed spectra. The data shall be available
to the Administrator on request for the length of time specified in
the applicable regulation.
8.7.4 For each sample spectrum, document the sampling
conditions, the sampling time (while the cell was being filled),
the time the spectrum was recorded, the instrumental conditions
(path length, temperature, pressure, resolution, integration time),
and the spectral file name. Keep a hard copy of these data
sheets.
8.8 Signal Transmittance. While sampling, monitor the signal
transmittance through the instrumental system. If signal
transmittance (relative to the background) drops below 95 percent
in any spectral region where the sample does not absorb infrared
energy, obtain a new background spectrum.
8.9 Post-run CTS. After each sampling run, record another CTS
spectrum.
8.10 Post-test QA
8.10.1 Inspect the sample spectra immediately after the run to
verify that the gas matrix composition was close to the expected
(assumed) gas matrix.
8.10.2 Verify that the sampling and instrumental parameters were
appropriate for the conditions encountered. For example, if the
moisture is much greater than anticipated, it will be necessary to
use a shorter path length or dilute the sample.
8.10.3 Compare the pre and post-run CTS spectra. They shall
agree to within −5 percent. See FTIR Protocol, Appendix E.
9.0 Quality Control
Follow the quality assurance procedures in the method, including
the analysis of pre and post-run calibration transfer standards
(Sections 8.5 and 8.9) and the post-test quality assurance
procedures in Section 8.10.
10.0 Calibration and Standardization
10.1 Signal-to-Noise Ratio (S/N). The S/N shall be sufficient to
meet the MAU in each analytical region.
10.2 Absorbance Pathlength. Verify the absorbance path length by
comparing CTS spectra to reference spectra of the calibration
gas(es). See FTIR Protocol, Appendix E.
10.3 Instrument Resolution. Measure the line width of
appropriate CTS band(s) and compare to reference CTS spectra to
verify instrumental resolution.
10.4 Apodization Function. Choose appropriate apodization
function. Determine any appropriate mathematical transformations
that are required to correct instrumental errors by measuring the
CTS. Any mathematical transformations must be documented and
reproducible.
10.5 FTIR Cell Volume. Evacuate the cell to ≤5 mmHg. Measure the
initial absolute temperature (Ti) and absolute pressure (Pi).
Connect a wet test meter (or a calibrated dry gas meter), and
slowly draw room air into the cell. Measure the meter volume (Vm),
meter absolute temperature (Tm), and meter absolute pressure (Pm),
and the cell final absolute temperature (Tf) and absolute pressure
(Pf). Calculate the FTIR cell volume Vss, including that of the
connecting tubing, as follows:

As an
alternative to the wet test meter/calibrated dry gas meter
procedure, measure the inside dimensions of the cell cylinder and
calculate its volume. 11.0 Procedure
Refer to Sections 4.6-4.11, Sections 5, 6, and 7, and the
appendices of the FTIR Protocol.
12.0 Data Analysis and Calculations
a. Data analysis is performed using appropriate reference
spectra whose concentrations can be verified using CTS spectra.
Various analytical programs are available to relate sample
absorbance to a concentration standard. Calculated concentrations
should be verified by analyzing spectral baselines after
mathematically subtracting scaled reference spectra from the sample
spectra. A full description of the data analysis and calculations
may be found in the FTIR Protocol (Sections 4.0, 5.0, 6.0 and
appendices).
b. Correct the calculated concentrations in sample spectra for
differences in absorption pathlength between the reference and
sample spectra by:

Where:
Ccorr = The pathlength corrected concentration. Ccalc = The initial
calculated concentration (output of the Multicomp program designed
for the compound). Lr = The pathlength associated with the
reference spectra. Ls = The pathlength associated with the sample
spectra. Ts = The absolute temperature (K) of the sample gas. Tr =
The absolute gas temperature (K) at which reference spectra were
recorded. 13.0 Reporting and Recordkeeping
All interferograms used in determining source concentration
shall be stored for the period of time required in the applicable
regulation. The Administrator has the option of requesting the
interferograms recorded during the test in electronic form as part
of the test report.
14.0 Method Performance
Refer to the FTIR Protocol.
15.0 Pollution Prevention [Reserved] 16.0 Waste Management
Laboratory standards prepared from the formaldehyde and phenol
are handled according to the instructions in the materials safety
data sheets (MSDS).
17.0 References
(1) “Field Validation Test Using Fourier Transform Infrared
(FTIR) Spectrometry To Measure Formaldehyde, Phenol and Methanol at
a Wool Fiberglass Production Facility.” Draft. U.S. Environmental
Protection Agency Report, Entropy, Inc., EPA Contract No. 68D20163,
Work Assignment I-32, December 1994 (docket item II-A-13).
(2) “Method 301 - Field Validation of Pollutant Measurement
Methods from Various Waste Media,” 40 CFR part 63, appendix A.
Method 319 - Determination of Filtration Efficiency for Paint
Overspray Arrestors 1.0 Scope and Application
1.1 This method applies to the determination of the initial,
particle size dependent, filtration efficiency for paint arrestors
over the particle diameter range from 0.3 to 10 µm. The method
applies to single and multiple stage paint arrestors or paint
arrestor media. The method is applicable to efficiency
determinations from 0 to 99 percent. Two test aerosols are used -
one liquid phase and one solid phase. Oleic acid, a low-volatility
liquid (CAS Number 112-80-1), is used to simulate the behavior of
wet paint overspray. The solid-phase aerosol is potassium chloride
salt (KCl, CAS Number 7447-40-7) and is used to simulate the
behavior of a dry overspray. The method is limited to determination
of the initial, clean filtration efficiency of the arrestor.
Changes in efficiency (either increase or decrease) due to the
accumulation of paint overspray on and within the arrestor are not
evaluated.
1.2 Efficiency is defined as 1 - Penetration (e.g., 70 percent
efficiency is equal to 0.30 penetration). Penetration is based on
the ratio of the downstream particle concentration to the upstream
concentration. It is often more useful, from a mathematical or
statistical point of view, to discuss the upstream and downstream
counts in terms of penetration rather than the derived efficiency
value. Thus, this document uses both penetration and efficiency as
appropriate.
1.3 For a paint arrestor system or subsystem which has been
tested by this method, adding additional filtration devices to the
system or subsystem shall be assumed to result in an efficiency of
at least that of the original system without the requirement for
additional testing. (For example, if the final stage of a
three-stage paint arrestor system has been tested by itself, then
the addition of the other two stages shall be assumed to maintain,
as a minimum, the filtration efficiency provided by the final stage
alone. Thus, in this example, if the final stage has been shown to
meet the filtration requirements of Table 1 of § 63.745 of subpart
GG, then the final stage in combination with any additional paint
arrestor stages also passes the filtration requirements.)
2.0 Summary of Method
2.1 This method applies to the determination of the fractional
(i.e., particle-size dependent) aerosol penetration of several
types of paint arrestors. Fractional penetration is computed from
aerosol concentrations measured upstream and downstream of an
arrestor installed in a laboratory test rig. The aerosol
concentrations upstream and downstream of the arrestors are
measured with an aerosol analyzer that simultaneously counts and
sizes the particles in the aerosol stream. The aerosol analyzer
covers the particle diameter size range from 0.3 to 10 µm in a
minimum of 12 contiguous sizing channels. Each sizing channel
covers a narrow range of particle diameters. For example, Channel 1
may cover from 0.3 to 0.4 µm, Channel 2 from 0.4 to 0.5 µm, * * *
By taking the ratio of the downstream to upstream counts on a
channel by channel basis, the penetration is computed for each of
the sizing channels.
2.2 The upstream and downstream aerosol measurements are made
while injecting the test aerosol into the air stream upstream of
the arrestor (ambient aerosol is removed with HEPA filters on the
inlet of the test rig). This test aerosol spans the particle size
range from 0.3 to 10 µm and provides sufficient upstream
concentration in each of the optical particle counter (OPC) sizing
channels to allow accurate calculation of penetration, down to
penetrations of approximately 0.01 (i.e., 1 percent penetration; 99
percent efficiency). Results are presented as a graph and a data
table showing the aerodynamic particle diameter and the
corresponding fractional efficiency.
3.0 Definitions
Aerodynamic Diameter - diameter of a unit density sphere having
the same aerodynamic properties as the particle in question.
Efficiency is defined as equal to 1 - Penetration.
Optical Particle Counter (OPC) - an instrument that counts
particles by size using light scattering. An OPC gives particle
diameters based on size, index of refraction, and shape.
Penetration - the fraction of the aerosol that penetrates the
filter at a given particle diameter. Penetration equals the
downstream concentration divided by the upstream concentration.
4.0 Interferences
4.1 The influence of the known interferences (particle losses)
are negated by correction of the data using blanks.
5.0 Safety
5.1 There are no specific safety precautions for this method
above those of good laboratory practice. This standard does not
purport to address all of the safety problems, if any, associated
with its use. It is the responsibility of the user of this method
to establish appropriate safety and health practices and determine
the applicability of regulatory limitations prior to use.
6.0 Equipment and Supplies
6.1 Test Facility. A schematic diagram of a test duct used in
the development of the method is shown in Figure 319-1.
6.1.1 The test section, paint spray section, and attached
transitions are constructed of stainless and galvanized steel. The
upstream and downstream ducting is 20 cm diameter polyvinyl
chloride (PVC). The upstream transition provides a 7 ° angle of
expansion to provide a uniform air flow distribution to the paint
arrestors. Aerosol concentration is measured upstream and
downstream of the test section to obtain the challenge and
penetrating aerosol concentrations, respectively. Because the
downstream ducting runs back under the test section, the challenge
and penetrating aerosol taps are located physically near each
other, thereby facilitating aerosol sampling and reducing
sample-line length. The inlet nozzles of the upstream and
downstream aerosol probes are designed to yield isokinetic sampling
conditions.
6.1.2 The configuration and dimensions of the test duct can
deviate from those of Figure 319-1 provided that the following key
elements are maintained: the test duct must meet the criteria
specified in Table 319-1; the inlet air is HEPA filtered; the
blower is on the upstream side of the duct thereby creating a
positive pressure in the duct relative to the surrounding room; the
challenge air has a temperature between 50 ° and 100 °F and a
relative humidity of less than 65 percent; the angle of the
upstream transition (if used) to the paint arrestor must not exceed
7 °; the angle of the downstream transition (if used) from the
paint arrestor must not exceed 30 °; the test duct must provide a
means for mixing the challenge aerosol with the upstream flow (in
lieu of any mixing device, a duct length of 15 duct diameters
fulfills this requirement); the test duct must provide a means for
mixing any penetrating aerosol with the downstream flow (in lieu of
any mixing device, a duct length of 15 duct diameters fulfills this
requirement); the test section must provide a secure and leak-free
mounting for single and multiple stage arrestors; and the test duct
may utilize a 180 ° bend in the downstream duct.
Table 319-1 - QC Control Limits
|
Frequency and
description |
Control limits |
OPC zero
count |
Each Test. OPC samples
HEPA-filtered air |
<50 counts per minute. |
OPC sizing
accuracy check |
Daily. Sample aerosolized PSL
spheres |
Peak of distribution should be
in correct OPC channel. |
Minimum counts per
channel for challenge aerosol |
Each Test |
Minimum total of 500 particle
counts per channel. |
Maximum particle
concentration |
Each Test. Needed to ensure
OPC is not overloaded |
<10% of manufacturer's
claimed upper limit corresponding to a 10% count error. |
Standard Deviation
of Penetration |
Computed for each test based
on the CV of the upstream and downstream counts |
<0.10 for 0.3 to 3 µm
diameter.
<0.30 for >3 µm diameter. |
0%
Penetration |
Monthly |
<0.01. |
100% Penetration -
KCl |
Triplicate tests performed
immediately before, during, or after triplicate arrestor tests |
0.3 to 1 µm: 0.90 to 1.10.
1 to 3 µm: 0.75 to 1.25.
3 to 10 µm: 0.50 to 1.50. |
100% Penetration -
Oleic Acid |
Triplicate tests performed
immediately before, during, or after triplicate arrestor tests |
0.3 to 1 µm: 0.90 to 1.10.
1 to 3 µm: 0.75 to 1.25.
3 to 10 µm: 0.50 to 1.50. |
6.2 Aerosol Generator. The aerosol generator is used to produce
a stable aerosol covering the particle size range from 0.3 to 10 µm
diameter. The generator used in the development of this method
consists of an air atomizing nozzle positioned at the top of a
0.30-m (12-in.) diameter, 1.3-m (51-in.) tall, acrylic,
transparent, spray tower. This tower allows larger sized particles,
which would otherwise foul the test duct and sample lines, to fall
out of the aerosol. It also adds drying air to ensure that the KCl
droplets dry to solid salt particles. After generation, the aerosol
passes through an aerosol neutralizer (Kr85 radioactive source) to
neutralize any electrostatic charge on the aerosol (electrostatic
charge is an unavoidable consequence of most aerosol generation
methods). To improve the mixing of the aerosol with the air stream,
the aerosol is injected counter to the airflow. Generators of other
designs may be used, but they must produce a stable aerosol
concentration over the 0.3 to 10 µm diameter size range; provide a
means of ensuring the complete drying of the KCl aerosol; and
utilize a charge neutralizer to neutralize any electrostatic charge
on the aerosol. The resultant challenge aerosol must meet the
minimum count per channel and maximum concentration criteria of
Table 319-1.
6.3 Installation of Paint Arrestor. The paint arrestor is to be
installed in the test duct in a manner that precludes air bypassing
the arrestor. Since arrestor media are often sold unmounted, a
mounting frame may be used to provide back support for the media in
addition to sealing it into the duct. The mounting frame for 20 in.
× 20 in. arrestors will have minimum open internal dimensions of 18
in. square. Mounting frames for 24 in. × 24 in. arrestors will have
minimum open internal dimensions of 22 in. square. The open
internal dimensions of the mounting frame shall not be less than 75
percent of the approach duct dimensions.
6.4 Optical Particle Counter. The upstream and downstream
aerosol concentrations are measured with a high-resolution optical
particle counter (OPC). To ensure comparability of test results,
the OPC shall utilize an optical design based on wide-angle light
scattering and provided a minimum of 12 contiguous particle sizing
channels from 0.3 to 10 µm diameter (based on response to PSL)
where, for each channel, the ratio of the diameter corresponding to
the upper channel bound to the lower channel bound must not exceed
1.5.
6.5 Aerosol Sampling System. The upstream and downstream sample
lines must be made of rigid electrically-grounded metallic tubing
having a smooth inside surface, and they must be rigidly secured to
prevent movement during testing. The upstream and downstream sample
lines are to be nominally identical in geometry. The use of a short
length (100 mm maximum) of straight flexible tubing to make the
final connection to the OPC is acceptable. The inlet nozzles of the
upstream and downstream probes must be sharp-edged and of
appropriate entrance diameter to maintain isokinetic sampling
within 20 percent of the air velocity.
6.5.1 The sampling system may be designed to acquire the
upstream and downstream samples using (a) sequential
upstream-downstream sampling with a single OPC, (b) simultaneous
upstream and downstream sampling with two OPC's, or (c) sequential
upstream-downstream sampling with two OPC's.
6.5.2 When two particle counters are used to acquire the
upstream and downstream counts, they must be closely matched in
flowrate and optical design.
6.6 Airflow Monitor. The volumetric airflow through the system
shall be measured with a calibrated orifice plate, flow nozzle, or
laminar flow element. The measurement device must have an accuracy
of 5 percent or better.
7.0 Reagents and Standards
7.1 The liquid test aerosol is reagent grade, 98 percent pure,
oleic acid (Table 319-2). The solid test aerosol is KCl aerosolized
from a solution of KCl in water. In addition to the test aerosol, a
calibration aerosol of monodisperse polystyrene latex (PSL) spheres
is used to verify the calibration of the OPC.
Table 319-2 - Properties of the Test and
Calibration Aerosols
|
Refractive index |
Density,
g/cm 3 |
Shape |
Oleic Acid
(liquid-phase challenge aerosol) |
1.46 nonabsorbing |
0.89 |
Spherical. |
KCl (solid-phase
challenge aerosol) |
1.49 |
1.98 |
Cubic or agglomerated
cubes. |
PSL (calibration
aerosol) |
1.59 nonabsorbing |
1.05 |
Spherical. |
8.0 Sample Collection, Preservation, and Storage
8.1 In this test, all sampling occurs in real-time, thus no
samples are collected that require preservation or storage during
the test. The paint arrestors are shipped and stored to avoid
structural damage or soiling. Each arrestor may be shipped in its
original box from the manufacturer or similar cardboard box.
Arrestors are stored at the test site in a location that keeps them
clean and dry. Each arrestor is clearly labeled for tracking
purposes.
9.0 Quality Control
9.1 Table 319-1 lists the QC control limits.
9.2 The standard deviation (σ) of the penetration (P) for a
given test at each of the 15 OPC sizing channels is computed from
the coefficient of variation (CV, the standard deviation divided by
the mean) of the upstream and downstream measurements as:

For a
properly operating system, the standard deviation of the
penetration is <0.10 at particle diameters from 0.3 to 3 µm and
less than 0.30 at diameters >3 µm.
9.3 Data Quality Objectives (DQO).
9.3.1 Fractional Penetration. From the triplicate tests of each
paint arrestor model, the standard deviation for the penetration
measurements at each particle size (i.e., for each sizing channel
of the OPC) is computed as:

where Pi
represents an individual penetration measurement, and P the average
of the 3 (n = 3) individual measurements.
9.3.2 Bias of the fractional penetration values is determined
from triplicate no-filter and HEPA filter tests. These tests
determine the measurement bias at 100 percent penetration and 0
percent penetration, respectively.
9.3.3 PSL-Equivalent Light Scattering Diameter. The precision
and bias of the OPC sizing determination are based on sampling a
known diameter of PSL and noting whether the particle counts peak
in the correct channel of the OPC. This is a pass/fail measurement
with no calculations involved.
9.3.4 Airflow. The precision of the measurement must be within 5
percent of the set point.
10.0 Calibration and Standardization
10.1 Optical Particle Counter. The OPC must have an up-to-date
factory calibration. Check the OPC zero at the beginning and end of
each test by sampling HEPA-filtered air. Verify the sizing accuracy
on a daily basis (for days when tests are performed) with 1-size
PSL spheres.
10.2 Airflow Measurement. Airflow measurement devices must have
an accuracy of 5 percent or better. Manometers used in conjunction
with the orifice plate must be inspected prior to use for proper
level, zero, and mechanical integrity. Tubing connections to the
manometer must be free from kinks and have secure connections.
10.3 Pressure Drop. Measure pressure drop across the paint
arrestor with an inclined manometer readable to within 0.01 in.
H2O. Prior to use, the level and zero of the manometer, and all
tubing connections, must be inspected and adjusted as needed.
11.0 Procedure
11.1 Filtration Efficiency. For both the oleic acid and KCl
challenges, this procedure is performed in triplicate using a new
arrestor for each test.
11.1.1 General Information and Test Duct Preparation
11.1.1.1 Use the “Test Run Sheet” form (Figure 319-2) to record
the test information.
Run Sheet Part 1. General Information Date and Time: Test Operator:
Test #: Paint Arrestor: Brand/Model Arrestor Assigned ID #
Condition of arrestor (i.e., is there any damage? Must be new
condition to proceed):
Manometer zero and level confirmed?
Part 2. Clean Efficiency Test Date and Time: Optical Particle
Counter: 20 min. warm up Zero count (<50 counts/min) Daily PSL
check PSL Diam: ___ µm File name for OPC data: Test Conditions: Air
Flow: ___ Temp & RH: Temp ___ °F RH ___ % Atm. Pressure: ___in. Hg
(From mercury barometer) Aerosol Generator: (record all operating
parameters) Test Aerosol: (Oleic acid or KCl) Arrestor: Pressure
drop: at start ___ in. H2O at end ___ in. H2O
Condition of arrestor at end of test (note any physical
deterioration):
Figure 319-2. Test Run Sheet
Other report formats which contain the same information are
acceptable.
11.1.1.2 Record the date, time, test operator, Test #, paint
arrestor brand/model and its assigned ID number. For tests with no
arrestor, record none.
11.1.1.3 Ensure that the arrestor is undamaged and is in “new”
condition.
11.1.1.4 Mount the arrestor in the appropriate frame. Inspect
for any airflow leak paths.
11.1.1.5 Install frame-mounted arrestor in the test duct.
Examine the installed arrestor to verify that it is sealed in the
duct. For tests with no arrestor, install the empty frame.
11.1.1.6 Visually confirm the manometer zero and level. Adjust
as needed.
11.1.2 Clean Efficiency Test.
11.1.2.1 Record the date and time upon beginning this
section.
11.1.2.2 Optical Particle Counter.
11.1.2.2.1 General: Operate the OPC per the manufacturer's
instructions allowing a minimum of 20 minutes warm up before making
any measurements.
11.1.2.2.2 Overload: The OPC will yield inaccurate data if the
aerosol concentration it is attempting to measure exceeds its
operating limit. To ensure reliable measurements, the maximum
aerosol concentration will not exceed 10 percent of the
manufacturer's claimed upper concentration limit corresponding to a
10 percent count error. If this value is exceeded, reduce the
aerosol concentration until the acceptable conditions are met.
11.1.2.2.3 Zero Count: Connect a HEPA capsule to the inlet of
the OPC and obtain printouts for three samples (each a minimum of
1-minute each). Record maximum cumulative zero count. If the count
rate exceeds 50 counts per minute, the OPC requires servicing
before continuing.
11.1.2.2.4 PSL Check of OPC Calibration: Confirm the calibration
of the OPC by sampling a known size PSL aerosol. Aerosolize the PSL
using an appropriate nebulizer. Record whether the peak count is
observed in the proper channel. If the peak is not seen in the
appropriate channel, have the OPC recalibrated.
11.1.2.3 Test Conditions:
11.1.2.3.1 Airflow: The test airflow corresponds to a nominal
face velocity of 120 FPM through the arrestor. For arrestors having
nominal 20 in. × 20 in. face dimensions, this measurement
corresponds to an airflow of 333 cfm. For arrestors having nominal
face dimensions of 24 in. × 24 in., this measurement corresponds to
an airflow of 480 cfm.
11.1.2.3.2 Temperature and Relative Humidity: The temperature
and relative humidity of the challenge air stream will be measured
to within an accuracy of ±2 °F and ±10 percent RH. To protect the
probe from fouling, it may be removed during periods of aerosol
generation.
11.1.2.3.3 Barometric Pressure: Use a mercury barometer. Record
the atmospheric pressure.
11.1.2.4 Upstream and Downstream Background Counts.
11.1.2.4.1 With the arrestor installed in the test duct and the
airflow set at the proper value, turn on the data acquisition
computer and bring up the data acquisition program.
11.1.2.4.2 Set the OPC settings for the appropriate test sample
duration with output for both printer and computer data
collection.
11.1.2.4.3 Obtain one set of upstream-downstream background
measurements.
11.1.2.4.4 After obtaining the upstream-downstream measurements,
stop data acquisition.
11.1.2.5 Efficiency Measurements:
11.1.2.5.1 Record the arrestor pressure drop.
11.1.2.5.2 Turn on the Aerosol Generator. Begin aerosol
generation and record the operating parameters.
11.1.2.5.3 Monitor the particle counts. Allow a minimum of 5
minutes for the generator to stabilize.
11.1.2.5.4 Confirm that the total particle count does not exceed
the predetermined upper limit. Adjust generator as needed.
11.1.2.5.5 Confirm that a minimum of 50 particle counts are
measured in the upstream sample in each of the OPC channels per
sample. (A minimum of 50 counts per channel per sample will yield
the required minimum 500 counts per channel total for the 10
upstream samples as specified in Table 319-1.) Adjust generator or
sample time as needed.
11.1.2.5.6 If you are unable to obtain a stable concentration
within the concentration limit and with the 50 count minimum per
channel, adjust the aerosol generator.
11.1.2.5.7 When the counts are stable, perform repeated
upstream-downstream sampling until 10 upstream-downstream
measurements are obtained.
11.1.2.5.8 After collection of the 10 upstream-downstream
samples, stop data acquisition and allow 2 more minutes for final
purging of generator.
11.1.2.5.9 Obtain one additional set of upstream-downstream
background samples.
11.1.2.5.10 After obtaining the upstream-downstream background
samples, stop data acquisition.
11.1.2.5.11 Record the arrestor pressure drop.
11.1.2.5.12 Turn off blower.
11.1.2.5.13 Remove the paint arrestor assembly from the test
duct. Note any signs of physical deterioration.
11.1.2.5.14 Remove the arrestor from the frame and place the
arrestor in an appropriate storage bag.
11.2 Control Test: 100 Percent Penetration Test. A 100 percent
penetration test must be performed immediately before each
individual paint arrestor test using the same challenge aerosol
substance (i.e., oleic acid or KCl) as to be used in the arrestor
test. These tests are performed with no arrestor installed in the
test housing. This test is a relatively stringent test of the
adequacy of the overall duct, sampling, measurement, and aerosol
generation system. The test is performed as a normal penetration
test except the paint arrestor is not used. A perfect system would
yield a measured penetration of 1 at all particle sizes. Deviations
from 1 can occur due to particle losses in the duct, differences in
the degree of aerosol uniformity (i.e., mixing) at the upstream and
downstream probes, and differences in particle transport efficiency
in the upstream and downstream sampling lines.
11.3 Control Test: 0 Percent Penetration. One 0 percent
penetration test must be performed at least monthly during testing.
The test is performed by using a HEPA filter rather than a paint
arrestor. This test assesses the adequacy of the instrument
response time and sample line lag.
12.0 Data Analysis and Calculations
12.1 Analysis. The analytical procedures for the fractional
penetration and flow velocity measurements are described in Section
11. Note that the primary measurements, those of the upstream and
downstream aerosol concentrations, are performed with the OPC which
acquires the sample and analyzes it in real time. Because all the
test data are collected in real time, there are no analytical
procedures performed subsequent to the actual test, only data
analysis.
12.2 Calculations.
12.2.1 Penetration.
Nomenclature U = Upstream particle count D = Downstream particle
count Ub = Upstream background count Db = Downstream background
count P100 = 100 percent penetration value determined immediately
prior to the arrestor test computed for each channel as:

P = Penetration of
the arrestor corrected for P100 ρ= sample standard deviation CV =
coefficient of variation = ρ/mean E = Efficiency.
Overbar denotes arithmetic mean of quantity.
Analysis of each test involves the following quantities:
• P100 value for each sizing channel from the 100 percent
penetration control test,
• 2 upstream background values,
• 2 downstream background values,
• 10 upstream values with aerosol generator on, and
• 10 downstream values with aerosol generator on.
Using the values associated with each sizing channel, the
penetration associated with each particle-sizing channel is
calculated as:
Most often, the background levels are small compared to the
values when the aerosol generator is on.
12.3 The relationship between the physical diameter (DPhysical)
as measured by the OPC to the aerodynamic diameter (DAero) is given
by:

Where: pO
= unit density of 1 g/cm 3. pParticle = the density of the
particle, 0.89 g/cm 3 for oleic acid. CCFPhysical = the Cunningham
Correction Factor at DPhysical. CCFAero = the Cunningham Correction
Factor at D Aero.
12.4 Presentation of Results. For a given arrestor, results will
be presented for:
• Triplicate arrestor tests with the liquid-phase challenge
aerosol,
• Triplicate arrestor tests with the solid-phase challenge
aerosol,
• Triplicate 100 percent penetration tests with the liquid-phase
challenge aerosol,
• Triplicate 100 percent penetration tests with the solid-phase
challenge aerosol, and
• One 0 percent filter test (using either the liquid-phase or
solid-phase aerosol and performed at least monthly).
12.4.1 Results for the paint arrestor test must be presented in
both graphical and tabular form. The X-axis of the graph will be a
logarithmic scale of aerodynamic diameter from 0.1 to 100 µm. The
Y-axis will be efficiency (%) on a linear scale from 0 to 100.
Plots for each individual run and a plot of the average of
triplicate solid-phase and of the average triplicate liquid-phase
tests must be prepared. All plots are to be based on point-to-point
plotting (i.e., no curve fitting is to be used). The data are to be
plotted based on the geometric mean diameter of each of the OPC's
sizing channels.
12.4.2 Tabulated data from each test must be provided. The data
must include the upper and lower diameter bound and geometric mean
diameter of each of the OPC sizing channels, the background
particle counts for each channel for each sample, the upstream
particle counts for each channel for each sample, the downstream
particle counts for each channel for each sample, the 100 percent
penetration values computed for each channel, and the 0 percent
penetration values computed for each channel.
13.0 Pollution Prevention
13.1 The quantities of materials to be aerosolized should be
prepared in accord with the amount needed for the current tests so
as to prevent wasteful excess.
14.0 Waste Management
14.1 Paint arrestors may be returned to originator, if
requested, or disposed of with regular laboratory waste.
15.0 References
1. Hanley, J.T., D.D. Smith and L. Cox. “Fractional Penetration
of Paint Overspray Arrestors, Draft Final Report,” EPA Cooperative
Agreement CR-817083-01-0, January 1994.
2. Hanley, J.T., D.D. Smith, and D.S. Ensor. “Define a
Fractional Efficiency Test Method that is Compatible with
Particulate Removal Air Cleaners Used in General Ventilation,”
Final Report, 671-RP, American Society of Heating, Refrigerating,
and Air-Conditioning Engineers, Inc., December 1993.
3. “Project Work and Quality Assurance Plan: Fractional
Penetration of Paint Overspray Arrestors, Category II,” EPA
Cooperative Agreement No. CR-817083, July 1994.
Test Method 320 - Measurement of Vapor Phase Organic and Inorganic
Emissions by Extractive Fourier Transform Infrared (FTIR)
Spectroscopy 1.0 Introduction
Persons unfamiliar with basic elements of FTIR spectroscopy
should not attempt to use this method. This method describes
sampling and analytical procedures for extractive emission
measurements using Fourier transform infrared (FTIR) spectroscopy.
Detailed analytical procedures for interpreting infrared spectra
are described in the “Protocol for the Use of Extractive Fourier
Transform Infrared (FTIR) Spectrometry in Analyses of Gaseous
Emissions from Stationary Sources,” hereafter referred to as the
“Protocol.” Definitions not given in this method are given in
appendix A of the Protocol. References to specific sections in the
Protocol are made throughout this Method. For additional
information refer to references 1 and 2, and other EPA reports,
which describe the use of FTIR spectrometry in specific field
measurement applications and validation tests. The sampling
procedure described here is extractive. Flue gas is extracted
through a heated gas transport and handling system. For some
sources, sample conditioning systems may be applicable. Some
examples are given in this method.
Note:
Sample conditioning systems may be used providing the method
validation requirements in Sections 9.2 and 13.0 of this method are
met.
1.1 Scope and Applicability.
1.1.1 Analytes. Analytes include hazardous air pollutants
(HAPs) for which EPA reference spectra have been developed. Other
compounds can also be measured with this method if reference
spectra are prepared according to section 4.6 of the protocol.
1.1.2 Applicability. This method applies to the analysis
of vapor phase organic or inorganic compounds which absorb energy
in the mid-infrared spectral region, about 400 to 4000 cm−1 (25 to
2.5 µm). This method is used to determine compound-specific
concentrations in a multi-component vapor phase sample, which is
contained in a closed-path gas cell. Spectra of samples are
collected using double beam infrared absorption spectroscopy. A
computer program is used to analyze spectra and report compound
concentrations.
1.2 Method Range and Sensitivity. Analytical range and
sensitivity depend on the frequency-dependent analyte absorptivity,
instrument configuration, data collection parameters, and gas
stream composition. Instrument factors include: (a) spectral
resolution, (b) interferometer signal averaging time, (c) detector
sensitivity and response, and (d) absorption path length.
1.2.1 For any optical configuration the analytical range is
between the absorbance values of about .01 (infrared transmittance
relative to the background = 0.98) and 1.0
(T = 0.1). (For absorbance >1.0 the relation between absorbance
and concentration may not be linear.)
1.2.2 The concentrations associated with this absorbance range
depend primarily on the cell path length and the sample
temperature. An analyte absorbance greater than 1.0, can be lowered
by decreasing the optical path length. Analyte absorbance increases
with a longer path length. Analyte detection also depends on the
presence of other species exhibiting absorbance in the same
analytical region. Additionally, the estimated lower absorbance (A)
limit
(A = 0.01) depends on the root mean square deviation (RMSD) noise
in the analytical region.
1.2.3 The concentration range of this method is determined by
the choice of optical configuration.
1.2.3.1 The absorbance for a given concentration can be
decreased by decreasing the path length or by diluting the sample.
There is no practical upper limit to the measurement range.
1.2.3.2 The analyte absorbance for a given concentration may be
increased by increasing the cell path length or (to some extent)
using a higher resolution. Both modifications also cause a
corresponding increased absorbance for all compounds in the sample,
and a decrease in the signal throughput. For this reason the
practical lower detection range (quantitation limit) usually
depends on sample characteristics such as moisture content of the
gas, the presence of other interferants, and losses in the sampling
system.
1.3 Sensitivity. The limit of sensitivity for an optical
configuration and integration time is determined using appendix D
of the Protocol: Minimum Analyte Uncertainty, (MAU). The MAU
depends on the RMSD noise in an analytical region, and on the
absorptivity of the analyte in the same region.
1.4 Data Quality. Data quality shall be determined by
executing Protocol pre-test procedures in appendices B to H of the
protocol and post-test procedures in appendices I and J of the
protocol.
1.4.1 Measurement objectives shall be established by the choice
of detection limit (DLi) and analytical uncertainty (AUi) for each
analyte.
1.4.2 An instrumental configuration shall be selected. An
estimate of gas composition shall be made based on previous test
data, data from a similar source or information gathered in a
pre-test site survey. Spectral interferants shall be identified
using the selected DLi and AUi and band areas from reference
spectra and interferant spectra. The baseline noise of the system
shall be measured in each analytical region to determine the MAU of
the instrument configuration for each analyte and interferant
(MIUi).
1.4.3 Data quality for the application shall be determined, in
part, by measuring the RMS (root mean square) noise level in each
analytical spectral region (appendix C of the Protocol). The RMS
noise is defined as the RMSD of the absorbance values in an
analytical region from the mean absorbance value in the region.
1.4.4 The MAU is the minimum analyte concentration for which the
AUi can be maintained; if the measured analyte concentration is
less than MAUi then data quality are unacceptable.
2.0 Summary of Method
2.1 Principle. References 4 through 7 provide background
material on infrared spectroscopy and quantitative analysis. A
summary is given in this section.
2.1.1 Infrared absorption spectroscopy is performed by directing
an infrared beam through a sample to a detector. The
frequency-dependent infrared absorbance of the sample is measured
by comparing this detector signal (single beam spectrum) to a
signal obtained without a sample in the beam path (background).
2.1.2 Most molecules absorb infrared radiation and the
absorbance occurs in a characteristic and reproducible pattern. The
infrared spectrum measures fundamental molecular properties and a
compound can be identified from its infrared spectrum alone.
2.1.3 Within constraints, there is a linear relationship between
infrared absorption and compound concentration. If this frequency
dependent relationship (absorptivity) is known (measured), it can
be used to determine compound concentration in a sample
mixture.
2.1.4 Absorptivity is measured by preparing, in the laboratory,
standard samples of compounds at known concentrations and measuring
the FTIR “reference spectra” of these standard samples. These
“reference spectra” are then used in sample analysis: (1) Compounds
are detected by matching sample absorbance bands with bands in
reference spectra, and (2) concentrations are measured by comparing
sample band intensities with reference band intensities.
2.1.5 This method is self-validating provided that the results
meet the performance requirement of the QA spike in sections 8.6.2
and 9.0 of this method, and results from a previous method
validation study support the use of this method in the
application.
2.2 Sampling and Analysis. In extractive sampling a probe
assembly and pump are used to extract gas from the exhaust of the
affected source and transport the sample to the FTIR gas cell.
Typically, the sampling apparatus is similar to that used for
single-component continuous emission monitor (CEM)
measurements.
2.2.1 The digitized infrared spectrum of the sample in the FTIR
gas cell is measured and stored on a computer. Absorbance band
intensities in the spectrum are related to sample concentrations by
what is commonly referred to as Beer's Law.

Where: Ai
= absorbance at a given frequency of the ith sample component. ai =
absorption coefficient (absorptivity) of the ith sample component.
b = path length of the cell. ci = concentration of the ith sample
component.
2.2.2 Analyte spiking is used for quality assurance (QA). In
this procedure (section 8.6.2 of this method) an analyte is spiked
into the gas stream at the back end of the sample probe. Analyte
concentrations in the spiked samples are compared to analyte
concentrations in unspiked samples. Since the concentration of the
spike is known, this procedure can be used to determine if the
sampling system is removing the spiked analyte(s) from the sample
stream.
2.3 Reference Spectra Availability. Reference spectra of
over 100 HAPs are available in the EPA FTIR spectral library on the
EMTIC (Emission Measurement Technical Information Center) computer
bulletin board service and at internet address
http://info.arnold.af.mil/epa/welcome.htm. Reference spectra
for HAPs, or other analytes, may also be prepared according to
section 4.6 of the Protocol.
2.4 Operator Requirements. The FTIR analyst shall be
trained in setting up the instrumentation, verifying the instrument
is functioning properly, and performing routine maintenance. The
analyst must evaluate the initial sample spectra to determine if
the sample matrix is consistent with pre-test assumptions and if
the instrument configuration is suitable. The analyst must be able
to modify the instrument configuration, if necessary.
2.4.1 The spectral analysis shall be supervised by someone
familiar with EPA FTIR Protocol procedures.
2.4.2 A technician trained in instrumental test methods is
qualified to install and operate the sampling system. This includes
installing the probe and heated line assembly, operating the
analyte spike system, and performing moisture and flow
measurements.
3.0 Definitions
See appendix A of the Protocol for definitions relating to
infrared spectroscopy. Additional definitions are given in sections
3.1 through 3.29.
3.1 Analyte. A compound that this method is used to
measure. The term “target analyte” is also used. This method is
multi-component and a number of analytes can be targeted for a
test.
3.2 Reference Spectrum. Infrared spectrum of an analyte
prepared under controlled, documented, and reproducible laboratory
conditions according to procedures in section 4.6 of the Protocol.
A library of reference spectra is used to measure analytes in gas
samples.
3.3 Standard Spectrum. A spectrum that has been prepared
from a reference spectrum through a (documented) mathematical
operation. A common example is de-resolving of reference spectra to
lower-resolution standard spectra (Protocol, appendix K to the
addendum of this method). Standard spectra, prepared by approved,
and documented, procedures can be used as reference spectra for
analysis.
3.4 Concentration. In this method concentration is
expressed as a molar concentration, in ppm-meters, or in
(ppm-meters)/K, where K is the absolute temperature (Kelvin). The
latter units allow the direct comparison of concentrations from
systems using different optical configurations or sampling
temperatures.
3.5 Interferant. A compound in the sample matrix whose
infrared spectrum overlaps with part of an analyte spectrum. The
most accurate analyte measurements are achieved when reference
spectra of interferants are used in the quantitative analysis with
the analyte reference spectra. The presence of an interferant can
increase the analytical uncertainty in the measured analyte
concentration.
3.6 Gas Cell. A gas containment cell that can be
evacuated. It is equipped with the optical components to pass the
infrared beam through the sample to the detector. Important cell
features include: path length (or range if variable), temperature
range, materials of construction, and total gas volume.
3.7 Sampling System. Equipment used to extract the sample
from the test location and transport the sample gas to the FTIR
analyzer. This includes sample conditioning systems.
3.8 Sample Analysis. The process of interpreting the
infrared spectra to obtain sample analyte concentrations. This
process is usually automated using a software routine employing a
classical least squares (cls), partial least squares (pls), or K-
or P-matrix method.
3.9 One hundred percent line. A double beam transmittance
spectrum obtained by combining two background single beam spectra.
Ideally, this line is equal to 100 percent transmittance (or zero
absorbance) at every frequency in the spectrum. Practically, a zero
absorbance line is used to measure the baseline noise in the
spectrum.
3.10 Background Deviation. A deviation from 100 percent
transmittance in any region of the 100 percent line. Deviations
greater than ±5 percent in an analytical region are unacceptable
(absorbance of 0.021 to −0.022). Such deviations indicate a change
in the instrument throughput relative to the background single
beam.
3.11 Batch Sampling. A procedure where spectra of
discreet, static samples are collected. The gas cell is filled with
sample and the cell is isolated. The spectrum is collected.
Finally, the cell is evacuated to prepare for the next sample.
3.12 Continuous Sampling. A procedure where spectra are
collected while sample gas is flowing through the cell at a
measured rate.
3.13 Sampling resolution. The spectral resolution used to
collect sample spectra.
3.14 Truncation. Limiting the number of interferogram
data points by deleting points farthest from the center burst (zero
path difference, ZPD).
3.15 Zero filling. The addition of points to the
interferogram. The position of each added point is interpolated
from neighboring real data points. Zero filling adds no information
to the interferogram, but affects line shapes in the absorbance
spectrum (and possibly analytical results).
3.16 Reference CTS. Calibration Transfer Standard spectra
that were collected with reference spectra.
3.17 CTS Standard. CTS spectrum produced by applying a
de-resolution procedure to a reference CTS.
3.18 Test CTS. CTS spectra collected at the sampling
resolution using the same optical configuration as for sample
spectra. Test spectra help verify the resolution, temperature and
path length of the FTIR system.
3.19 RMSD. Root Mean Square Difference, defined in EPA
FTIR Protocol, appendix A.
3.20 Sensitivity. The noise-limited compound-dependent
detection limit for the FTIR system configuration. This is
estimated by the MAU. It depends on the RMSD in an analytical
region of a zero absorbance line.
3.21 Quantitation Limit. The lower limit of detection for
the FTIR system configuration in the sample spectra. This is
estimated by mathematically subtracting scaled reference spectra of
analytes and interferences from sample spectra, then measuring the
RMSD in an analytical region of the subtracted spectrum. Since the
noise in subtracted sample spectra may be much greater than in a
zero absorbance spectrum, the quantitation limit is generally much
higher than the sensitivity. Removing spectral interferences from
the sample or improving the spectral subtraction can lower the
quantitation limit toward (but not below) the sensitivity.
3.22 Independent Sample. A unique volume of sample gas;
there is no mixing of gas between two consecutive independent
samples. In continuous sampling two independent samples are
separated by at least 5 cell volumes. The interval between
independent measurements depends on the cell volume and the sample
flow rate (through the cell).
3.23 Measurement. A single spectrum of flue gas contained
in the FTIR cell.
3.24 Run. A run consists of a series of measurements. At
a minimum a run includes 8 independent measurements spaced over 1
hour.
3.25 Validation. Validation of FTIR measurements is
described in sections 13.0 through 13.4 of this method. Validation
is used to verify the test procedures for measuring specific
analytes at a source. Validation provides proof that the method
works under certain test conditions.
3.26 Validation Run. A validation run consists of at
least 24 measurements of independent samples. Half of the samples
are spiked and half are not spiked. The length of the run is
determined by the interval between independent samples.
3.27 Screening. Screening is used when there is little or
no available information about a source. The purpose of screening
is to determine what analytes are emitted and to obtain information
about important sample characteristics such as moisture,
temperature, and interferences. Screening results are
semi-quantitative (estimated concentrations) or qualitative
(identification only). Various optical and sampling configurations
may be used. Sample conditioning systems may be evaluated for their
effectiveness in removing interferences. It is unnecessary to
perform a complete run under any set of sampling conditions.
Spiking is not necessary, but spiking can be a useful screening
tool for evaluating the sampling system, especially if a reactive
or soluble analyte is used for the spike.
3.28 Emissions Test. An FTIR emissions test is performed
according specific sampling and analytical procedures. These
procedures, for the target analytes and the source, are based on
previous screening and validation results. Emission results are
quantitative. A QA spike (sections 8.6.2 and 9.2 of this method) is
performed under each set of sampling conditions using a
representative analyte. Flow, gas temperature and diluent data are
recorded concurrently with the FTIR measurements to provide mass
emission rates for detected compounds.
3.29 Surrogate. A surrogate is a compound that is used in
a QA spike procedure (section 8.6.2 of this method) to represent
other compounds. The chemical and physical properties of a
surrogate shall be similar to the compounds it is chosen to
represent. Under given sampling conditions, usually a single
sampling factor is of primary concern for measuring the target
analytes: for example, the surrogate spike results can be
representative for analytes that are more reactive, more soluble,
have a lower absorptivity, or have a lower vapor pressure than the
surrogate itself.
4.0 Interferences
Interferences are divided into two classifications: analytical
and sampling.
4.1 Analytical Interferences. An analytical interference
is a spectral feature that complicates (in extreme cases may
prevent) the analysis of an analyte. Analytical interferences are
classified as background or spectral interference.
4.1.1 Background Interference. This results from a change
in throughput relative to the single beam background. It is
corrected by collecting a new background and proceeding with the
test. In severe instances the cause must be identified and
corrected. Potential causes include: (1) Deposits on reflective
surfaces or transmitting windows, (2) changes in detector
sensitivity, (3) a change in the infrared source output, or (4)
failure in the instrument electronics. In routine sampling
throughput may degrade over several hours. Periodically a new
background must be collected, but no other corrective action will
be required.
4.1.2 Spectral Interference. This results from the
presence of interfering compound(s) (interferant) in the sample.
Interferant spectral features overlap analyte spectral features.
Any compound with an infrared spectrum, including analytes, can
potentially be an interferant. The Protocol measures absorbance
band overlap in each analytical region to determine if potential
interferants shall be classified as known interferants (FTIR
Protocol, section 4.9 and appendix B). Water vapor and CO2 are
common spectral interferants. Both of these compounds have strong
infrared spectra and are present in many sample matrices at high
concentrations relative to analytes. The extent of interference
depends on the (1) interferant concentration, (2) analyte
concentration, and (3) the degree of band overlap. Choosing an
alternate analytical region can minimize or avoid the spectral
interference. For example, CO2 interferes with the analysis of the
670 cm−1 benzene band. However, benzene can also be measured near
3000 cm−1 (with less sensitivity).
4.2 Sampling System Interferences. These prevent analytes
from reaching the instrument. The analyte spike procedure is
designed to measure sampling system interference, if any.
4.2.1 Temperature. A temperature that is too low causes
condensation of analytes or water vapor. The materials of the
sampling system and the FTIR gas cell usually set the upper limit
of temperature.
4.2.2 Reactive Species. Anything that reacts with
analytes. Some analytes, like formaldehyde, polymerize at lower
temperatures.
4.2.3 Materials. Poor choice of material for probe, or
sampling line may remove some analytes. For example, HF reacts with
glass components.
4.2.4 Moisture. In addition to being a spectral
interferant, condensed moisture removes soluble compounds.
5.0 Safety
The hazards of performing this method are those associated with
any stack sampling method and the same precautions shall be
followed. Many HAPs are suspected carcinogens or present other
serious health risks. Exposure to these compounds should be avoided
in all circumstances. For instructions on the safe handling of any
particular compound, refer to its material safety data sheet. When
using analyte standards, always ensure that gases are properly
vented and that the gas handling system is leak free. (Always
perform a leak check with the system under maximum vacuum and,
again, with the system at greater than ambient pressure.) Refer to
section 8.2 of this method for leak check procedures. This method
does not address all of the potential safety risks associated with
its use. Anyone performing this method must follow safety and
health practices consistent with applicable legal requirements and
with prudent practice for each application.
6.0 Equipment and Supplies Note:
Mention of trade names or specific products does not constitute
endorsement by the Environmental Protection Agency.
The equipment and supplies are based on the schematic of a
sampling system shown in Figure 1. Either the batch or continuous
sampling procedures may be used with this sampling system.
Alternative sampling configurations may also be used, provided that
the data quality objectives are met as determined in the
post-analysis evaluation. Other equipment or supplies may be
necessary, depending on the design of the sampling system or the
specific target analytes.
6.1 Sampling Probe. Glass, stainless steel, or other
appropriate material of sufficient length and physical integrity to
sustain heating, prevent adsorption of analytes, and to transport
analytes to the infrared gas cell. Special materials or
configurations may be required in some applications. For instance,
high stack sample temperatures may require special steel or cooling
the probe. For very high moisture sources it may be desirable to
use a dilution probe.
6.2 Particulate Filters. A glass wool plug (optional)
inserted at the probe tip (for large particulate removal) and a
filter (required) rated for 99 percent removal efficiency at
1-micron (e.g., Balston”) connected at the outlet of the heated
probe.
6.3 Sampling Line/Heating System. Heated (sufficient to
prevent condensation) stainless steel, polytetrafluoroethane, or
other material inert to the analytes.
6.4 Gas Distribution Manifold. A heated manifold allowing
the operator to control flows of gas standards and samples directly
to the FTIR system or through sample conditioning systems. Usually
includes heated flow meter, heated valve for selecting and sending
sample to the analyzer, and a by-pass vent. This is typically
constructed of stainless steel tubing and fittings, and
high-temperature valves.
6.5 Stainless Steel Tubing. Type 316, appropriate
diameter (e.g., 3/8 in.) and length for heated connections. Higher
grade stainless may be desirable in some applications.
6.6 Calibration/Analyte Spike Assembly. A three way valve
assembly (or equivalent) to introduce analyte or surrogate spikes
into the sampling system at the outlet of the probe upstream of the
out-of-stack particulate filter and the FTIR analytical system.
6.7 Mass Flow Meter (MFM). These are used for measuring
analyte spike flow. The MFM shall be calibrated in the range of 0
to 5 L/min and be accurate to ±2 percent (or better) of the flow
meter span.
6.8 Gas Regulators. Appropriate for individual gas
standards.
6.9 Polytetrafluoroethane Tubing. Diameter (e.g., 3/8
in.) and length suitable to connect cylinder regulators to gas
standard manifold.
6.10 Sample Pump. A leak-free pump (e.g., KNF TM), with
by-pass valve, capable of producing a sample flow rate of at least
10 L/min through 100 ft of sample line. If the pump is positioned
upstream of the distribution manifold and FTIR system, use a heated
pump that is constructed from materials non-reactive to the
analytes. If the pump is located downstream of the FTIR system, the
gas cell sample pressure will be lower than ambient pressure and it
must be recorded at regular intervals.
6.11 Gas Sample Manifold. Secondary manifold to control
sample flow at the inlet to the FTIR manifold. This is optional,
but includes a by-pass vent and heated rotameter.
6.12 Rotameter. A 0 to 20 L/min rotameter. This meter
need not be calibrated.
6.13 FTIR Analytical System. Spectrometer and detector,
capable of measuring the analytes to the chosen detection limit.
The system shall include a personal computer with compatible
software allowing automated collection of spectra.
6.14 FTIR Cell Pump. Required for the batch sampling
technique, capable of evacuating the FTIR cell volume within 2
minutes. The pumping speed shall allow the operator to obtain 8
sample spectra in 1 hour.
6.15 Absolute Pressure Gauge. Capable of measuring
pressure from 0 to 1000 mmHg to within ±2.5 mmHg (e.g., Baratron
TM).
6.16 Temperature Gauge. Capable of measuring the cell
temperature to within ±2 °C.
6.17 Sample Conditioning. One option is a condenser
system, which is used for moisture removal. This can be helpful in
the measurement of some analytes. Other sample conditioning
procedures may be devised for the removal of moisture or other
interfering species.
6.17.1 The analyte spike procedure of section 9.2 of this
method, the QA spike procedure of section 8.6.2 of this method, and
the validation procedure of section 13 of this method demonstrate
whether the sample conditioning affects analyte concentrations.
Alternatively, measurements can be made with two parallel FTIR
systems; one measuring conditioned sample, the other measuring
unconditioned sample.
6.17.2 Another option is sample dilution. The dilution factor
measurement must be documented and accounted for in the reported
concentrations. An alternative to dilution is to lower the
sensitivity of the FTIR system by decreasing the cell path length,
or to use a short-path cell in conjunction with a long path cell to
measure more than one concentration range.
7.0 Reagents and Standards
7.1 Analyte(s) and Tracer Gas. Obtain a certified gas
cylinder mixture containing all of the analyte(s) at concentrations
within ±2 percent of the emission source levels (expressed in
ppm-meter/K). If practical, the analyte standard cylinder shall
also contain the tracer gas at a concentration which gives a
measurable absorbance at a dilution factor of at least 10:1. Two
ppm SF6 is sufficient for a path length of 22 meters at 250 °F.
7.2 Calibration Transfer Standard(s). Select the
calibration transfer standards (CTS) according to section 4.5 of
the FTIR Protocol. Obtain a National Institute of Standards and
Technology (NIST) traceable gravimetric standard of the CTS (±2
percent).
7.3 Reference Spectra. Obtain reference spectra for each
analyte, interferant, surrogate, CTS, and tracer. If EPA reference
spectra are not available, use reference spectra prepared according
to procedures in section 4.6 of the EPA FTIR Protocol.
8.0 Sampling and Analysis Procedure
Three types of testing can be performed: (1) Screening, (2)
emissions test, and (3) validation. Each is defined in section 3 of
this method. Determine the purpose(s) of the FTIR test. Test
requirements include: (a) AUi, DLi, overall fractional uncertainty,
OFUi, maximum expected concentration (CMAXi), and tAN for each, (b)
potential interferants, (c) sampling system factors, e.g., minimum
absolute cell pressure, (Pmin), FTIR cell volume (VSS), estimated
sample absorption pathlength, LS′, estimated sample pressure, PS′,
TS′, signal integration time (tSS), minimum instrumental linewidth,
MIL, fractional error, and (d) analytical regions, e.g., m = 1 to
M, lower wavenumber position, FLm, center wavenumber position, FCm,
and upper wavenumber position, FUm, plus interferants, upper
wavenumber position of the CTS absorption band, FFUm, lower
wavenumber position of the CTS absorption band, FFLm, wavenumber
range FNU to FNL. If necessary, sample and acquire an initial
spectrum. From analysis of this preliminary spectrum determine a
suitable operational path length. Set up the sampling train as
shown in Figure 1 or use an appropriate alternative configuration.
Sections 8.1 through 8.11 of this method provide guidance on
pre-test calculations in the EPA protocol, sampling and analytical
procedures, and post-test protocol calculations.
8.1 Pretest Preparations and Evaluations. Using the
procedure in section 4.0 of the FTIR Protocol, determine the
optimum sampling system configuration for measuring the target
analytes. Use available information to make reasonable assumptions
about moisture content and other interferences.
8.1.1 Analytes. Select the required detection limit (DLi)
and the maximum permissible analytical uncertainty (AUi) for each
analyte (labeled from 1 to i). Estimate, if possible, the maximum
expected concentration for each analyte, CMAXi. The expected
measurement range is fixed by DLi and CMAXi for each analyte
(i).
8.1.2 Potential Interferants. List the potential
interferants. This usually includes water vapor and CO2, but may
also include some analytes and other compounds.
8.1.3. Optical Configuration. Choose an optical
configuration that can measure all of the analytes within the
absorbance range of .01 to 1.0 (this may require more than one path
length). Use Protocol sections 4.3 to 4.8 for guidance in choosing
a configuration and measuring CTS.
8.1.4 Fractional Reproducibility Uncertainty (FRUi). The
FRU is determined for each analyte by comparing CTS spectra taken
before and after the reference spectra were measured. The EPA
para-xylene reference spectra were collected on 10/31/91 and
11/01/91 with corresponding CTS spectra “cts1031a,” and “cts1101b.”
The CTS spectra are used to estimate the reproducibility (FRU) in
the system that was used to collect the references. The FRU must be
<AU. Appendix E of the protocol is used to calculate the FRU
from CTS spectra. Figure 2 plots results for 0.25 cm−1 CTS spectra
in EPA reference library: S3 (cts1101b−cts1031a), and S4 [(cts1101b
+ cts1031a)/2]. The RMSD (SRMS) is calculated in the subtracted
baseline, S3, in the corresponding CTS region from 850 to 1065
cm−1. The area (BAV) is calculated in the same region of the
averaged CTS spectrum, S4.
8.1.5 Known Interferants. Use appendix B of the EPA FTIR
Protocol.
8.1.6 Calculate the Minimum Analyte Uncertainty, MAU (section
1.3 of this method discusses MAU and protocol appendix D gives the
MAU procedure). The MAU for each analyte, i, and each analytical
region, m, depends on the RMS noise.
8.1.7 Analytical Program. See FTIR Protocol, section
4.10. Prepare computer program based on the chosen analytical
technique. Use as input reference spectra of all target analytes
and expected interferants. Reference spectra of additional
compounds shall also be included in the program if their presence
(even if transient) in the samples is considered possible. The
program output shall be in ppm (or ppb) and shall be corrected for
differences between the reference path length, LR, temperature, TR,
and pressure, PR, and the conditions used for collecting the sample
spectra. If sampling is performed at ambient pressure, then any
pressure correction is usually small relative to corrections for
path length and temperature, and may be neglected.
8.2 Leak-Check
8.2.1 Sampling System. A typical FTIR extractive sampling
train is shown in Figure 1. Leak check from the probe tip to pump
outlet as follows: Connect a 0-to 250-mL/min rate meter (rotameter
or bubble meter) to the outlet of the pump. Close off the inlet to
the probe, and record the leak rate. The leak rate shall be ≤200
mL/min.
8.2.2 Analytical System Leak check. Leak check the FTIR
cell under vacuum and under pressure (greater than ambient). Leak
check connecting tubing and inlet manifold under pressure.
8.2.2.1 For the evacuated sample technique, close the valve to
the FTIR cell, and evacuate the absorption cell to the minimum
absolute pressure Pmin. Close the valve to the pump, and determine
the change in pressure ΔPv after 2 minutes.
8.2.2.2 For both the evacuated sample and purging techniques,
pressurize the system to about 100 mmHg above atmospheric pressure.
Isolate the pump and determine the change in pressure ΔPp after 2
minutes.
8.2.2.3 Measure the barometric pressure, Pb in mmHg.
8.2.2.4 Determine the percent leak volume %VL for the signal
integration time tSS and for ΔPmax, i.e., the larger of ΔPv
or ΔPp, as follows:

Where: 50
= 100% divided by the leak-check time of 2 minutes.
8.2.2.5 Leak volumes in excess of 4 percent of the FTIR system
volume VSS are unacceptable.
8.3 Detector Linearity. Once an optical configuration is
chosen, use one of the procedures of sections 8.3.1 through 8.3.3
to verify that the detector response is linear. If the detector
response is not linear, decrease the aperture, or attenuate the
infrared beam. After a change in the instrument configuration
perform a linearity check until it is demonstrated that the
detector response is linear.
8.3.1 Vary the power incident on the detector by modifying the
aperture setting. Measure the background and CTS at three
instrument aperture settings: (1) at the aperture setting to be
used in the testing, (2) at one half this aperture and (3) at twice
the proposed testing aperture. Compare the three CTS spectra. CTS
band areas shall agree to within the uncertainty of the cylinder
standard and the RMSD noise in the system. If test aperture is the
maximum aperture, collect CTS spectrum at maximum aperture, then
close the aperture to reduce the IR throughput by half. Collect a
second background and CTS at the smaller aperture setting and
compare the spectra again.
8.3.2 Use neutral density filters to attenuate the infrared
beam. Set up the FTIR system as it will be used in the test
measurements. Collect a CTS spectrum. Use a neutral density filter
to attenuate the infrared beam (either immediately after the source
or the interferometer) to approximately 1/2 its original intensity.
Collect a second CTS spectrum. Use another filter to attenuate the
infrared beam to approximately 1/4 its original intensity. Collect
a third background and CTS spectrum. Compare the CTS spectra. CTS
band areas shall agree to within the uncertainty of the cylinder
standard and the RMSD noise in the system.
8.3.3 Observe the single beam instrument response in a frequency
region where the detector response is known to be zero. Verify that
the detector response is “flat” and equal to zero in these
regions.
8.4 Data Storage Requirements. All field test spectra
shall be stored on a computer disk and a second backup copy must
stored on a separate disk. The stored information includes sample
interferograms, processed absorbance spectra, background
interferograms, CTS sample interferograms and CTS absorbance
spectra. Additionally, documentation of all sample conditions,
instrument settings, and test records must be recorded on hard copy
or on computer medium. Table 1 gives a sample presentation of
documentation.
8.5 Background Spectrum. Evacuate the gas cell to ≤5
mmHg, and fill with dry nitrogen gas to ambient pressure (or purge
the cell with 10 volumes of dry nitrogen). Verify that no
significant amounts of absorbing species (for example water vapor
and CO2) are present. Collect a background spectrum, using a signal
averaging period equal to or greater than the averaging period for
the sample spectra. Assign a unique file name to the background
spectrum. Store two copies of the background interferogram and
processed single-beam spectrum on separate computer disks (one copy
is the back-up).
8.5.1 Interference Spectra. If possible, collect spectra
of known and suspected major interferences using the same optical
system that will be used in the field measurements. This can be
done on-site or earlier. A number of gases, e.g. CO2, SO2, CO, NH3,
are readily available from cylinder gas suppliers.
8.5.2 Water vapor spectra can be prepared by the following
procedure. Fill a sample tube with distilled water. Evacuate above
the sample and remove dissolved gasses by alternately freezing and
thawing the water while evacuating. Allow water vapor into the FTIR
cell, then dilute to atmospheric pressure with nitrogen or dry air.
If quantitative water spectra are required, follow the reference
spectrum procedure for neat samples (protocol, section 4.6). Often,
interference spectra need not be quantitative, but for best results
the absorbance must be comparable to the interference absorbance in
the sample spectra.
8.6 Pre-Test Calibrations
8.6.1 Calibration Transfer Standard. Evacuate the gas
cell to ≤5 mmHg absolute pressure, and fill the FTIR cell to
atmospheric pressure with the CTS gas. Alternatively, purge the
cell with 10 cell volumes of CTS gas. (If purge is used, verify
that the CTS concentration in the cell is stable by collecting two
spectra 2 minutes apart as the CTS gas continues to flow. If the
absorbance in the second spectrum is no greater than in the first,
within the uncertainty of the gas standard, then this can be used
as the CTS spectrum.) Record the spectrum.
8.6.2 QA Spike. This procedure assumes that the method
has been validated for at least some of the target analytes at the
source. For emissions testing perform a QA spike. Use a certified
standard, if possible, of an analyte, which has been validated at
the source. One analyte standard can serve as a QA surrogate for
other analytes which are less reactive or less soluble than the
standard. Perform the spike procedure of section 9.2 of this
method. Record spectra of at least three independent (section 3.22
of this method) spiked samples. Calculate the spiked component of
the analyte concentration. If the average spiked concentration is
within 0.7 to 1.3 times the expected concentration, then proceed
with the testing. If applicable, apply the correction factor from
the Method 301 of this appendix validation test (not the result
from the QA spike).
8.7 Sampling. If analyte concentrations vary rapidly with
time, continuous sampling is preferable using the smallest cell
volume, fastest sampling rate and fastest spectra collection rate
possible. Continuous sampling requires the least operator
intervention even without an automated sampling system. For
continuous monitoring at one location over long periods, Continuous
sampling is preferred. Batch sampling and continuous static
sampling are used for screening and performing test runs of finite
duration. Either technique is preferred for sampling several
locations in a matter of days. Batch sampling gives reasonably good
time resolution and ensures that each spectrum measures a discreet
(and unique) sample volume. Continuous static (and continuous)
sampling provide a very stable background over long periods. Like
batch sampling, continuous static sampling also ensures that each
spectrum measures a unique sample volume. It is essential that the
leak check procedure under vacuum (section 8.2 of this method) is
passed if the batch sampling procedure is used. It is essential
that the leak check procedure under positive pressure is passed if
the continuous static or continuous sampling procedures are used.
The sampling techniques are described in sections 8.7.1 through
8.7.2 of this method.
8.7.1 Batch Sampling. Evacuate the absorbance cell to ≤5
mmHg absolute pressure. Fill the cell with exhaust gas to ambient
pressure, isolate the cell, and record the spectrum. Before taking
the next sample, evacuate the cell until no spectral evidence of
sample absorption remains. Repeat this procedure to collect eight
spectra of separate samples in 1 hour.
8.7.2 Continuous Static Sampling. Purge the FTIR cell
with 10 cell volumes of sample gas. Isolate the cell, collect the
spectrum of the static sample and record the pressure. Before
measuring the next sample, purge the cell with 10 more cell volumes
of sample gas.
8.8 Sampling QA and Reporting
8.8.1 Sample integration times shall be sufficient to achieve
the required signal-to-noise ratio. Obtain an absorbance spectrum
by filling the cell with N2. Measure the RMSD in each analytical
region in this absorbance spectrum. Verify that the number of scans
used is sufficient to achieve the target MAU.
8.8.2 Assign a unique file name to each spectrum.
8.8.3 Store two copies of sample interferograms and processed
spectra on separate computer disks.
8.8.4 For each sample spectrum, document the sampling
conditions, the sampling time (while the cell was being filled),
the time the spectrum was recorded, the instrumental conditions
(path length, temperature, pressure, resolution, signal integration
time), and the spectral file name. Keep a hard copy of these data
sheets.
8.9 Signal Transmittance. While sampling, monitor the
signal transmittance. If signal transmittance (relative to the
background) changes by 5 percent or more (absorbance = -.02 to .02)
in any analytical spectral region, obtain a new background
spectrum.
8.10 Post-test CTS. After the sampling run, record
another CTS spectrum.
8.11 Post-test QA
8.11.1 Inspect the sample spectra immediately after the run to
verify that the gas matrix composition was close to the expected
(assumed) gas matrix.
8.11.2 Verify that the sampling and instrumental parameters were
appropriate for the conditions encountered. For example, if the
moisture is much greater than anticipated, it may be necessary to
use a shorter path length or dilute the sample.
8.11.3 Compare the pre- and post-test CTS spectra. The peak
absorbance in pre- and post-test CTS must be ±5 percent of the mean
value. See appendix E of the FTIR Protocol.
9.0 Quality Control
Use analyte spiking (sections 8.6.2, 9.2 and 13.0 of this
method) to verify that the sampling system can transport the
analytes from the probe to the FTIR system.
9.1 Spike Materials. Use a certified standard (accurate
to ±2 percent) of the target analyte, if one can be obtained. If a
certified standard cannot be obtained, follow the procedures in
section 4.6.2.2 of the FTIR Protocol.
9.2 Spiking Procedure. QA spiking (section 8.6.2 of this
method) is a calibration procedure used before testing. QA spiking
involves following the spike procedure of sections 9.2.1 through
9.2.3 of this method to obtain at least three spiked samples. The
analyte concentrations in the spiked samples shall be compared to
the expected spike concentration to verify that the
sampling/analytical system is working properly. Usually, when QA
spiking is used, the method has already been validated at a similar
source for the analyte in question. The QA spike demonstrates that
the validated sampling/analytical conditions are being duplicated.
If the QA spike fails then the sampling/analytical system shall be
repaired before testing proceeds. The method validation procedure
(section 13.0 of this method) involves a more extensive use of the
analyte spike procedure of sections 9.2.1 through 9.2.3 of this
method. Spectra of at least 12 independent spiked and 12
independent unspiked samples are recorded. The concentration
results are analyzed statistically to determine if there is a
systematic bias in the method for measuring a particular analyte.
If there is a systematic bias, within the limits allowed by Method
301 of this appendix, then a correction factor shall be applied to
the analytical results. If the systematic bias is greater than the
allowed limits, this method is not valid and cannot be used.
9.2.1 Introduce the spike/tracer gas at a constant flow rate of
≤10 percent of the total sample flow, when possible.
Note:
Use the rotameter at the end of the sampling train to estimate
the required spike/tracer gas flow rate.
Use a flow device, e.g., mass flow meter (# 2 percent), to
monitor the spike flow rate. Record the spike flow rate every 10
minutes.
9.2.2 Determine the response time (RT) of the system by
continuously collecting spectra of the spiked effluent until the
spectrum of the spiked component is constant for 5 minutes. The RT
is the interval from the first measurement until the spike becomes
constant. Wait for twice the duration of the RT, then collect
spectra of two independent spiked gas samples. Duplicate analyses
of the spiked concentration shall be within 5 percent of the mean
of the two measurements.
9.2.3 Calculate the dilution ratio using the tracer gas as
follows:

DF = Dilution
factor of the spike gas; this value shall be ≥10. SF6(dir) = SF6
(or tracer gas) concentration measured directly in undiluted spike
gas. SF6(spk) = Diluted SF6 (or tracer gas) concentration measured
in a spiked sample. Spikedir = Concentration of the analyte in the
spike standard measured by filling the FTIR cell directly. CS =
Expected concentration of the spiked samples. Unspike = Native
concentration of analytes in unspiked samples. 10.0 Calibration and
Standardization
10.1 Signal-to-Noise Ratio (S/N). The RMSD in the noise
must be less than one tenth of the minimum analyte peak absorbance
in each analytical region. For example if the minimum peak
absorbance is 0.01 at the required DL, then RMSD measured over the
entire analytical region must be ≤0.001.
10.2 Absorbance Path length. Verify the absorbance path
length by comparing reference CTS spectra to test CTS spectra. See
appendix E of the FTIR Protocol.
10.3 Instrument Resolution. Measure the line width of
appropriate test CTS band(s) to verify instrument resolution.
Alternatively, compare CTS spectra to a reference CTS spectrum, if
available, measured at the nominal resolution.
10.4 Apodization Function.In transforming the sample
interferograms to absorbance spectra use the same apodization
function that was used in transforming the reference spectra.
10.5 FTIR Cell Volume. Evacuate the cell to ≤5 mmHg.
Measure the initial absolute temperature (Ti) and absolute pressure
(Pi). Connect a wet test meter (or a calibrated dry gas meter), and
slowly draw room air into the cell. Measure the meter volume (Vm),
meter absolute temperature (Tm), and meter absolute pressure (Pm);
and the cell final absolute temperature (Tf) and absolute pressure
(Pf). Calculate the FTIR cell volume VSS, including that of the
connecting tubing, as follows:

11.0 Data
Analysis and Calculations
Analyte concentrations shall be measured using reference spectra
from the EPA FTIR spectral library. When EPA library spectra are
not available, the procedures in section 4.6 of the Protocol shall
be followed to prepare reference spectra of all the target
analytes.
11.1 Spectral De-resolution. Reference spectra can be
converted to lower resolution standard spectra (section 3.3 of this
method) by truncating the original reference sample and background
interferograms. Appendix K of the FTIR Protocol gives specific
deresolution procedures. Deresolved spectra shall be transformed
using the same apodization function and level of zero filling as
the sample spectra. Additionally, pre-test FTIR protocol
calculations (e.g., FRU, MAU, FCU) shall be performed using the
de-resolved standard spectra.
11.2 Data Analysis. Various analytical programs are
available for relating sample absorbance to a concentration
standard. Calculated concentrations shall be verified by analyzing
residual baselines after mathematically subtracting scaled
reference spectra from the sample spectra. A full description of
the data analysis and calculations is contained in the FTIR
Protocol (sections 4.0, 5.0, 6.0 and appendices). Correct the
calculated concentrations in the sample spectra for differences in
absorption path length and temperature between the reference and
sample spectra using equation 6,

Where:
Ccorr = Concentration, corrected for path length. Ccalc =
Concentration, initial calculation (output of the analytical
program designed for the compound). Lr = Reference spectra path
length. Ls = Sample spectra path length. Ts = Absolute temperature
of the sample gas, K. Tr = Absolute gas temperature of reference
spectra, K. Ps = Sample cell pressure. Pr = Reference spectrum
sample pressure. 12.0 Method Performance
12.1 Spectral Quality. Refer to the FTIR Protocol
appendices for analytical requirements, evaluation of data quality,
and analysis of uncertainty.
12.2 Sampling QA/QC. The analyte spike procedure of
section 9 of this method, the QA spike of section 8.6.2 of this
method, and the validation procedure of section 13 of this method
are used to evaluate the performance of the sampling system and to
quantify sampling system effects, if any, on the measured
concentrations. This method is self-validating provided that the
results meet the performance requirement of the QA spike in
sections 9.0 and 8.6.2 of this method and results from a previous
method validation study support the use of this method in the
application. Several factors can contribute to uncertainty in the
measurement of spiked samples. Factors which can be controlled to
provide better accuracy in the spiking procedure are listed in
sections 12.2.1 through 12.2.4 of this method.
12.2.1 Flow meter. An accurate mass flow meter is
accurate to ±1 percent of its span. If a flow of 1 L/min is
monitored with such a MFM, which is calibrated in the range of 0-5
L/min, the flow measurement has an uncertainty of 5 percent. This
may be improved by re-calibrating the meter at the specific flow
rate to be used.
12.2.2 Calibration gas. Usually the calibration standard
is certified to within ±2 percent. With reactive analytes, such as
HCl, the certified accuracy in a commercially available standard
may be no better than ±5 percent.
12.2.3 Temperature. Temperature measurements of the cell
shall be quite accurate. If practical, it is preferable to measure
sample temperature directly, by inserting a thermocouple into the
cell chamber instead of monitoring the cell outer wall
temperature.
12.2.4 Pressure. Accuracy depends on the accuracy of the
barometer, but fluctuations in pressure throughout a day may be as
much as 2.5 percent due to weather variations.
13.0 Method Validation Procedure
This validation procedure, which is based on EPA Method 301 (40
CFR part 63, appendix (A), may be used to validate this method for
the analytes in a gas matrix. Validation at one source may also
apply to another type of source, if it can be shown that the
exhaust gas characteristics are similar at both sources.
13.1 Section 6.0 of Method 301 (40 CFR part 63, appendix A), the
Analyte Spike procedure, is used with these modifications. The
statistical analysis of the results follows section 12.0 of EPA
Method 301. Section 3 of this method defines terms that are not
defined in Method 301.
13.1.1 The analyte spike is performed dynamically. This means
the spike flow is continuous and constant as spiked samples are
measured.
13.1.2 The spike gas is introduced at the back of the sample
probe.
13.1.3 Spiked effluent is carried through all sampling
components downstream of the probe.
13.1.4 A single FTIR system (or more) may be used to collect and
analyze spectra (not quadruplicate integrated sampling trains).
13.1.5 All of the validation measurements are performed
sequentially in a single “run” (section 3.26 of this method).
13.1.6 The measurements analyzed statistically are each
independent (section 3.22 of this method).
13.1.7 A validation data set can consist of more than 12 spiked
and 12 unspiked measurements.
13.2 Batch Sampling. The procedure in sections 13.2.1
through 13.2.2 may be used for stable processes. If process
emissions are highly variable, the procedure in section 13.2.3
shall be used.
13.2.1 With a single FTIR instrument and sampling system, begin
by collecting spectra of two unspiked samples. Introduce the spike
flow into the sampling system and allow 10 cell volumes to purge
the sampling system and FTIR cell. Collect spectra of two spiked
samples. Turn off the spike and allow 10 cell volumes of unspiked
sample to purge the FTIR cell. Repeat this procedure until the 24
(or more) samples are collected.
13.2.2 In batch sampling, collect spectra of 24 distinct
samples. (Each distinct sample consists of filling the cell to
ambient pressure after the cell has been evacuated.)
13.2.3 Alternatively, a separate probe assembly, line, and
sample pump can be used for spiked sample. Verify and document that
sampling conditions are the same in both the spiked and the
unspiked sampling systems. This can be done by wrapping both sample
lines in the same heated bundle. Keep the same flow rate in both
sample lines. Measure samples in sequence in pairs. After two
spiked samples are measured, evacuate the FTIR cell, and turn the
manifold valve so that spiked sample flows to the FTIR cell. Allow
the connecting line from the manifold to the FTIR cell to purge
thoroughly (the time depends on the line length and flow rate).
Collect a pair of spiked samples. Repeat the procedure until at
least 24 measurements are completed.
13.3 Simultaneous Measurements With Two FTIR Systems. If
unspiked effluent concentrations of the target analyte(s) vary
significantly with time, it may be desirable to perform
synchronized measurements of spiked and unspiked sample. Use two
FTIR systems, each with its own cell and sampling system to perform
simultaneous spiked and unspiked measurements. The optical
configurations shall be similar, if possible. The sampling
configurations shall be the same. One sampling system and FTIR
analyzer shall be used to measure spiked effluent. The other
sampling system and FTIR analyzer shall be used to measure unspiked
flue gas. Both systems shall use the same sampling procedure (i.e.,
batch or continuous).
13.3.1 If batch sampling is used, synchronize the cell
evacuation, cell filling, and collection of spectra. Fill both
cells at the same rate (in cell volumes per unit time).
13.3.2 If continuous sampling is used, adjust the sample flow
through each gas cell so that the same number of cell volumes pass
through each cell in a given time (i.e. TC1 = TC2).
13.4 Statistical Treatment. The statistical procedure of
EPA Method 301 of this appendix, section 12.0 is used to evaluate
the bias and precision. For FTIR testing a validation “run” is
defined as spectra of 24 independent samples, 12 of which are
spiked with the analyte(s) and 12 of which are not spiked.
13.4.1 Bias. Determine the bias (defined by EPA Method
301 of this appendix, section 12.1.1) using equation 7:
B=Sm −
CS Where: B = Bias at spike level. Sm = Mean
concentration of the analyte spiked samples. CS = Expected
concentration of the spiked samples.
13.4.2 Correction Factor. Use section 6.3.2.2 of Method
301 of this appendix to evaluate the statistical significance of
the bias. If it is determined that the bias is significant, then
use section 6.3.3 of Method 301 to calculate a correction factor
(CF). Analytical results of the test method are multiplied by the
correction factor, if 0.7 ≤CF ≤1.3. If is determined that the bias
is significant and CF >±30 percent, then the test method is
considered to “not valid.”
13.4.3 If measurements do not pass validation, evaluate the
sampling system, instrument configuration, and analytical system to
determine if improper set-up or a malfunction was the cause. If so,
repair the system and repeat the validation.
14.0 Pollution Prevention
The extracted sample gas is vented outside the enclosure
containing the FTIR system and gas manifold after the analysis. In
typical method applications the vented sample volume is a small
fraction of the source volumetric flow and its composition is
identical to that emitted from the source. When analyte spiking is
used, spiked pollutants are vented with the extracted sample gas.
Approximately 1.6 × 10−4 to 3.2 × 10−4 lbs of a single HAP may be
vented to the atmosphere in a typical validation run of 3 hours.
(This assumes a molar mass of 50 to 100 g, spike rate of 1.0 L/min,
and a standard concentration of 100 ppm). Minimize emissions by
keeping the spike flow off when not in use.
15.0 Waste Management
Small volumes of laboratory gas standards can be vented through
a laboratory hood. Neat samples must be packed and disposed
according to applicable regulations. Surplus materials may be
returned to supplier for disposal.
16.0 References
1. “Field Validation Test Using Fourier Transform Infrared
(FTIR) Spectrometry To Measure Formaldehyde, Phenol and Methanol at
a Wool Fiberglass Production Facility.” Draft. U.S. Environmental
Protection Agency Report, EPA Contract No. 68D20163, Work
Assignment I-32, September 1994.
2. “FTIR Method Validation at a Coal-Fired Boiler”. Prepared for
U.S. Environmental Protection Agency, Research Triangle Park, NC.
Publication No.: EPA-454/R95-004, NTIS No.: PB95-193199. July,
1993.
3. “Method 301 - Field Validation of Pollutant Measurement
Methods from Various Waste Media,” 40 CFR part 63, appendix A.
4. “Molecular Vibrations; The Theory of Infrared and Raman
Vibrational Spectra,” E. Bright Wilson, J.C. Decius, and P.C.
Cross, Dover Publications, Inc., 1980. For a less intensive
treatment of molecular rotational-vibrational spectra see, for
example, “Physical Chemistry,” G.M. Barrow, chapters 12, 13, and
14, McGraw Hill, Inc., 1979.
5. “Fourier Transform Infrared Spectrometry,” Peter R. Griffiths
and James de Haseth, Chemical Analysis, 83, 16-25,(1986), P.J.
Elving, J.;D. Winefordner and I.M. Kolthoff (ed.), John Wiley and
Sons.
6. “Computer-Assisted Quantitative Infrared Spectroscopy,”
Gregory L. McClure (ed.), ASTM Special Publication 934 (ASTM),
1987.
7. “Multivariate Least-Squares Methods Applied to the
Quantitative Spectral Analysis of Multicomponent Mixtures,” Applied
Spectroscopy, 39(10), 73-84, 1985.
Table 1 - Example Presentation of Sampling
Documentation
Sample time |
Spectrum file name |
Background file name |
Sample conditioning |
Process condition |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Sample time |
Spectrum file |
Interferogram |
Resolution |
Scans |
Apodization |
Gain |
CTS Spectrum |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|

Addendum to Test
Method 320 - Protocol for the Use of Extractive Fourier Transform
Infrared (FTIR) Spectrometry for the Analyses of Gaseous Emissions
from Stationary Sources 1.0 Introduction
The purpose of this addendum is to set general guidelines for
the use of modern FTIR spectroscopic methods for the analysis of
gas samples extracted from the effluent of stationary emission
sources. This addendum outlines techniques for developing and
evaluating such methods and sets basic requirements for reporting
and quality assurance procedures.
1.1 Nomenclature
1.1.1 Appendix A to this addendum lists definitions of the
symbols and terms used in this Protocol, many of which have been
taken directly from American Society for Testing and Materials
(ASTM) publication E 131-90a, entitled “Terminology Relating to
Molecular Spectroscopy.”
1.1.2 Except in the case of background spectra or where
otherwise noted, the term “spectrum” refers to a double-beam
spectrum in units of absorbance vs. wavenumber (cm−1).
1.1.3 The term “Study” in this addendum refers to a publication
that has been subjected to EPA- or peer-review.
2.0 Applicability and Analytical Principle
2.1 Applicability. This Protocol applies to the
determination of compound-specific concentrations in single- and
multiple-component gas phase samples using double-beam absorption
spectroscopy in the mid-infrared band. It does not specifically
address other FTIR applications, such as single-beam spectroscopy,
analysis of open-path (non-enclosed) samples, and continuous
measurement techniques. If multiple spectrometers, absorption
cells, or instrumental linewidths are used in such analyses, each
distinct operational configuration of the system must be evaluated
separately according to this Protocol.
2.2 Analytical Principle
2.2.1 In the mid-infrared band, most molecules exhibit
characteristic gas phase absorption spectra that may be recorded by
FTIR systems. Such systems consist of a source of mid-infrared
radiation, an interferometer, an enclosed sample cell of known
absorption pathlength, an infrared detector, optical elements for
the transfer of infrared radiation between components, and gas flow
control and measurement components. Adjunct and integral computer
systems are used for controlling the instrument, processing the
signal, and for performing both Fourier transforms and quantitative
analyses of spectral data.
2.2.2 The absorption spectra of pure gases and of mixtures of
gases are described by a linear absorbance theory referred to as
Beer's Law. Using this law, modern FTIR systems use computerized
analytical programs to quantify compounds by comparing the
absorption spectra of known (reference) gas samples to the
absorption spectrum of the sample gas. Some standard mathematical
techniques used for comparisons are classical least squares,
inverse least squares, cross-correlation, factor analysis, and
partial least squares. Reference A describes several of these
techniques, as well as additional techniques, such as
differentiation methods, linear baseline corrections, and
non-linear absorbance corrections.
3.0 General Principles of Protocol Requirements
The characteristics that distinguish FTIR systems from gas
analyzers used in instrumental gas analysis methods (e.g., Methods
6C and 7E of appendix A to part 60 of this chapter) are: (1)
Computers are necessary to obtain and analyze data; (2) chemical
concentrations can be quantified using previously recorded infrared
reference spectra; and (3) analytical assumptions and results,
including possible effects of interfering compounds, can be
evaluated after the quantitative analysis. The following general
principles and requirements of this Protocol are based on these
characteristics.
3.1 Verifiability and Reproducibility of Results. Store
all data and document data analysis techniques sufficient to allow
an independent agent to reproduce the analytical results from the
raw interferometric data.
3.2 Transfer of Reference Spectra. To determine whether
reference spectra recorded under one set of conditions (e.g.,
optical bench, instrumental linewidth, absorption pathlength,
detector performance, pressure, and temperature) can be used to
analyze sample spectra taken under a different set of conditions,
quantitatively compare “calibration transfer standards” (CTS) and
reference spectra as described in this Protocol.
Note:
The CTS may, but need not, include analytes of interest). To
effect this, record the absorption spectra of the CTS (a)
immediately before and immediately after recording reference
spectra and (b) immediately after recording sample spectra.
3.3 Evaluation of FTIR Analyses. The applicability,
accuracy, and precision of FTIR measurements are influenced by a
number of interrelated factors, which may be divided into two
classes:
3.3.1 Sample-Independent Factors. Examples are system
configuration and performance (e.g., detector sensitivity and
infrared source output), quality and applicability of reference
absorption spectra, and type of mathematical analyses of the
spectra. These factors define the fundamental limitations of FTIR
measurements for a given system configuration. These limitations
may be estimated from evaluations of the system before samples are
available. For example, the detection limit for the absorbing
compound under a given set of conditions may be estimated from the
system noise level and the strength of a particular absorption
band. Similarly, the accuracy of measurements may be estimated from
the analysis of the reference spectra.
3.3.2 Sample-Dependent Factors. Examples are spectral
interferants (e.g., water vapor and CO2) or the overlap of spectral
features of different compounds and contamination deposits on
reflective surfaces or transmitting windows. To maximize the
effectiveness of the mathematical techniques used in spectral
analysis, identification of interferants (a standard initial step)
and analysis of samples (includes effect of other analytical
errors) are necessary. Thus, the Protocol requires post-analysis
calculation of measurement concentration uncertainties for the
detection of these potential sources of measurement error.
4.0 Pre-Test Preparations and Evaluations
Before testing, demonstrate the suitability of FTIR spectrometry
for the desired application according to the procedures of this
section.
4.1 Identify Test Requirements. Identify and record the
test requirements described in sections 4.1.1 through 4.1.4 of this
addendum. These values set the desired or required goals of the
proposed analysis; the description of methods for determining
whether these goals are actually met during the analysis comprises
the majority of this Protocol.
4.1.1 Analytes (specific chemical species) of interest. Label
the analytes from i = 1 to I.
4.1.2 Analytical uncertainty limit (AUi). The AUi is the maximum
permissible fractional uncertainty of analysis for the i th analyte
concentration, expressed as a fraction of the analyte concentration
in the sample.
4.1.3 Required detection limit for each analyte (DLi, ppm). The
detection limit is the lowest concentration of an analyte for which
its overall fractional uncertainty (OFUi) is required to be less
than its analytical uncertainty limit (AUi).
4.1.4 Maximum expected concentration of each analyte (CMAXi,
ppm).
4.2 Identify Potential Interferants. Considering the
chemistry of the process or results of previous studies, identify
potential interferants, i.e., the major effluent constituents and
any relatively minor effluent constituents that possess either
strong absorption characteristics or strong structural similarities
to any analyte of interest. Label them 1 through Nj, where the
subscript “j” pertains to potential interferants. Estimate the
concentrations of these compounds in the effluent (CPOTj, ppm).
4.3 Select and Evaluate the Sampling System. Considering
the source, e.g., temperature and pressure profiles, moisture
content, analyte characteristics, and particulate concentration),
select the equipment for extracting gas samples. Recommended are a
particulate filter, heating system to maintain sample temperature
above the dew point for all sample constituents at all points
within the sampling system (including the filter), and sample
conditioning system (e.g., coolers, water-permeable membranes that
remove water or other compounds from the sample, and dilution
devices) to remove spectral interferants or to protect the sampling
and analytical components. Determine the minimum absolute sample
system pressure (Pmin, mmHg) and the infrared absorption cell
volume (VSS, liter). Select the techniques and/or equipment for the
measurement of sample pressures and temperatures.
4.4 Select Spectroscopic System. Select a spectroscopic
configuration for the application. Approximate the absorption
pathlength (LS′, meter), sample pressure (PS′, kPa), absolute
sample temperature TS′, and signal integration period (tSS,
seconds) for the analysis. Specify the nominal minimum instrumental
linewidth (MIL) of the system. Verify that the fractional error at
the approximate values PS′ and TS′ is less than one half the
smallest value AUi (see section 4.1.2 of this addendum).
4.5 Select Calibration Transfer Standards (CTS's). Select CTS's
that meet the criteria listed in sections 4.5.1, 4.5.2, and 4.5.3
of this addendum.
Note:
It may be necessary to choose preliminary analytical regions
(see section 4.7 of this addendum), identify the minimum analyte
linewidths, or estimate the system noise level (see section 4.12 of
this addendum) before selecting the CTS. More than one compound may
be needed to meet the criteria; if so, obtain separate cylinders
for each compound.
4.5.1 The central wavenumber position of each analytical region
shall lie within 25 percent of the wavenumber position of at least
one CTS absorption band.
4.5.2 The absorption bands in section 4.5.1 of this addendum
shall exhibit peak absorbances greater than ten times the value
RMSEST (see section 4.12 of this addendum) but less than 1.5
absorbance units.
4.5.3 At least one absorption CTS band within the operating
range of the FTIR instrument shall have an instrument-independent
linewidth no greater than the narrowest analyte absorption band.
Perform and document measurements or cite Studies to determine
analyte and CTS compound linewidths.
4.5.4 For each analytical region, specify the upper and lower
wavenumber positions (FFUm and FFLm, respectively) that bracket the
CTS absorption band or bands for the associated analytical region.
Specify the wavenumber range, FNU to FNL, containing the absorption
band that meets the criterion of section 4.5.3 of this
addendum.
4.5.5 Associate, whenever possible, a single set of CTS gas
cylinders with a set of reference spectra. Replacement CTS gas
cylinders shall contain the same compounds at concentrations within
5 percent of that of the original CTS cylinders; the entire
absorption spectra (not individual spectral segments) of the
replacement gas shall be scaled by a factor between 0.95 and 1.05
to match the original CTS spectra.
4.6 Prepare Reference Spectra
Note:
Reference spectra are available in a permanent soft copy from
the EPA spectral library on the EMTIC (Emission Measurement
Technical Information Center) computer bulletin board; they may be
used if applicable.
4.6.1 Select the reference absorption pathlength (LR) of the
cell.
4.6.2 Obtain or prepare a set of chemical standards for each
analyte, potential and known spectral interferants, and CTS. Select
the concentrations of the chemical standards to correspond to the
top of the desired range.
4.6.2.1 Commercially-Prepared Chemical Standards.
Chemical standards for many compounds may be obtained from
independent sources, such as a specialty gas manufacturer, chemical
company, or commercial laboratory. These standards (accurate to
within ±2 percent) shall be prepared according to EPA Traceability
Protocol (see Reference D) or shall be traceable to NIST standards.
Obtain from the supplier an estimate of the stability of the
analyte concentration. Obtain and follow all of the supplier's
recommendations for recertifying the analyte concentration.
4.6.2.2 Self-Prepared Chemical Standards. Chemical
standards may be prepared by diluting certified commercially
prepared chemical gases or pure analytes with ultra-pure carrier
(UPC) grade nitrogen according to the barometric and volumetric
techniques generally described in Reference A, section A4.6.
4.6.3 Record a set of the absorption spectra of the CTS {R1},
then a set of the reference spectra at two or more concentrations
in duplicate over the desired range (the top of the range must be
less than 10 times that of the bottom), followed by a second set of
CTS spectra {R2}. (If self-prepared standards are used, see section
4.6.5 of this addendum before disposing of any of the standards.)
The maximum accepted standard concentration-pathlength product
(ASCPP) for each compound shall be higher than the maximum
estimated concentration-pathlength products for both analytes and
known interferants in the effluent gas. For each analyte, the
minimum ASCPP shall be no greater than ten times the
concentration-pathlength product of that analyte at its required
detection limit.
4.6.4 Permanently store the background and interferograms in
digitized form. Document details of the mathematical process for
generating the spectra from these interferograms. Record the sample
pressure (PR), sample temperature (TR), reference absorption
pathlength (LR), and interferogram signal integration period (tSR).
Signal integration periods for the background interferograms shall
be ≥tSR. Values of PR, LR, and tSR shall not deviate by more than
±1 percent from the time of recording [R1] to that of recording
[R2].
4.6.5 If self-prepared chemical standards are employed and
spectra of only two concentrations are recorded for one or more
compounds, verify the accuracy of the dilution technique by
analyzing the prepared standards for those compounds with a
secondary (non-FTIR) technique in accordance with sections 4.6.5.1
through 4.6.5.4 of this addendum.
4.6.5.1 Record the response of the secondary technique to each
of the four standards prepared.
4.6.5.2 Perform a linear regression of the response values
(dependant variable) versus the accepted standard concentration
(ASC) values (independent variable), with the regression
constrained to pass through the zero-response, zero ASC point.
4.6.5.3 Calculate the average fractional difference between the
actual response values and the regression-predicted values (those
calculated from the regression line using the four ASC values as
the independent variable).
4.6.5.4 If the average fractional difference value calculated in
section 4.6.5.3 of this addendum is larger for any compound than
the corresponding AUi, the dilution technique is not sufficiently
accurate and the reference spectra prepared are not valid for the
analysis.
4.7 Select Analytical Regions. Using the general
considerations in section 7 of Reference A and the spectral
characteristics of the analytes and interferants, select the
analytical regions for the application. Label them m = 1 to M.
Specify the lower, center and upper wavenumber positions of each
analytical region (FLm, FCm, and FUm, respectively). Specify the
analytes and interferants which exhibit absorption in each
region.
4.8 Determine Fractional Reproducibility Uncertainties.
Using appendix E of this addendum, calculate the fractional
reproducibility uncertainty for each analyte (FRUi) from a
comparison of [R1] and [R2]. If FRUi >AUi for any analyte, the
reference spectra generated in accordance with section 4.6 of this
addendum are not valid for the application.
4.9 Identify Known Interferants. Using appendix B of this
addendum, determine which potential interferants affect the analyte
concentration determinations. Relabel these potential interferant
as “known” interferants, and designate these compounds from k = 1
to K. Appendix B to this addendum also provides criteria for
determining whether the selected analytical regions are
suitable.
4.10 Prepare Computerized Analytical Programs
4.10.1 Choose or devise mathematical techniques (e.g, classical
least squares, inverse least squares, cross-correlation, and factor
analysis) based on equation 4 of Reference A that are appropriate
for analyzing spectral data by comparison with reference
spectra.
4.10.2 Following the general recommendations of Reference A,
prepare a computer program or set of programs that analyzes all of
the analytes and known interferants, based on the selected
analytical regions (section 4.7 of this addendum) and the prepared
reference spectra (section 4.6 of this addendum). Specify the
baseline correction technique (e.g., determining the slope and
intercept of a linear baseline contribution in each analytical
region) for each analytical region, including all relevant
wavenumber positions.
4.10.3 Use programs that provide as output [at the reference
absorption pathlength (LR), reference gas temperature (TR), and
reference gas pressure (PR)] the analyte concentrations, the known
interferant concentrations, and the baseline slope and intercept
values. If the sample absorption pathlength (LS), sample gas
temperature (TS), or sample gas pressure (PS) during the actual
sample analyses differ from LR, TR, and PR, use a program or set of
programs that applies multiplicative corrections to the derived
concentrations to account for these variations, and that provides
as output both the corrected and uncorrected values. Include in the
report of the analysis (see section 7.0 of this addendum) the
details of any transformations applied to the original reference
spectra (e.g., differentiation), in such a fashion that all
analytical results may be verified by an independent agent from the
reference spectra and data spectra alone.
4.11 Determine the Fractional Calibration Uncertainty.
Calculate the fractional calibration uncertainty for each analyte
(FCUi) according to appendix F of this addendum, and compare these
values to the fractional uncertainty limits (AUi; see section 4.1.2
of this addendum). If FCUi >AUi, either the reference spectra or
analytical programs for that analyte are unsuitable.
4.12 Verify System Configuration Suitability. Using
appendix C of this addendum, measure or obtain estimates of the
noise level (RMSEST, absorbance) of the FTIR system. Alternatively,
construct the complete spectrometer system and determine the values
RMSSm using appendix G of this addendum. Estimate the minimum
measurement uncertainty for each analyte (MAUi, ppm) and known
interferant (MIUk, ppm) using appendix D of this addendum. Verify
that (a) MAUi <(AUi)(DLi), FRUi <AUi, and FCUi <AUi for
each analyte and that (b) the CTS chosen meets the requirements
listed in sections 4.5.1 through 4.5.5 of this addendum.
5.0 Sampling and Analysis Procedure
5.1 Analysis System Assembly and Leak-Test. Assemble the
analysis system. Allow sufficient time for all system components to
reach the desired temperature. Then, determine the leak-rate (LR)
and leak volume (VL), where VL = LR tSS. Leak volumes shall be ≤4
percent of VSS.
5.2 Verify Instrumental Performance. Measure the noise
level of the system in each analytical region using the procedure
of appendix G of this addendum. If any noise level is higher than
that estimated for the system in section 4.12 of this addendum,
repeat the calculations of appendix D of this addendum and verify
that the requirements of section 4.12 of this addendum are met; if
they are not, adjust or repair the instrument and repeat this
section.
5.3 Determine the Sample Absorption Pathlength
Record a background spectrum. Then, fill the absorption cell
with CTS at the pressure PR and record a set of CTS spectra [R3].
Store the background and unscaled CTS single beam interferograms
and spectra. Using appendix H of this addendum, calculate the
sample absorption pathlength (LS) for each analytical region. The
values LS shall not differ from the approximated sample pathlength
LS′ (see section 4.4 of this addendum) by more than 5 percent.
5.4 Record Sample Spectrum. Connect the sample line to
the source. Either evacuate the absorption cell to an absolute
pressure below 5 mmHg before extracting a sample from the effluent
stream into the absorption cell, or pump at least ten cell volumes
of sample through the cell before obtaining a sample. Record the
sample pressure PS. Generate the absorbance spectrum of the sample.
Store the background and sample single beam interferograms, and
document the process by which the absorbance spectra are generated
from these data. (If necessary, apply the spectral transformations
developed in section 5.6.2 of this addendum). The resulting sample
spectrum is referred to below as SS.
Note:
Multiple sample spectra may be recorded according to the
procedures of section 5.4 of this addendum before performing
sections 5.5 and 5.6 of this addendum.
5.5 Quantify Analyte Concentrations. Calculate the
unscaled analyte concentrations RUAi and unscaled interferant
concentrations RUIK using the programs developed in section 4 of
this addendum. To correct for pathlength and pressure variations
between the reference and sample spectra, calculate the scaling
factor, RLPS using equation A.1,

Calculate
the final analyte and interferant concentrations RSAi and RSIk
using equations A.2 and A.3,
5.6 Determine Fractional Analysis Uncertainty. Fill the
absorption cell with CTS at the pressure PS. Record a set of CTS
spectra [R4]. Store the background and CTS single beam
interferograms. Using appendix H of this addendum, calculate the
fractional analysis uncertainty (FAU) for each analytical region.
If the FAU indicated for any analytical region is greater than the
required accuracy requirements determined in sections 4.1.1 through
4.1.4 of this addendum, then comparisons to previously recorded
reference spectra are invalid in that analytical region, and the
analyst shall perform one or both of the procedures of sections
5.6.1 through 5.6.2 of this addendum.
5.6.1 Perform instrumental checks and adjust the instrument to
restore its performance to acceptable levels. If adjustments are
made, repeat sections 5.3, 5.4 (except for the recording of a
sample spectrum), and 5.5 of this addendum to demonstrate that
acceptable uncertainties are obtained in all analytical
regions.
5.6.2 Apply appropriate mathematical transformations (e.g.,
frequency shifting, zero-filling, apodization, smoothing) to the
spectra (or to the interferograms upon which the spectra are based)
generated during the performance of the procedures of section 5.3
of this addendum. Document these transformations and their
reproducibility. Do not apply multiplicative scaling of the
spectra, or any set of transformations that is mathematically
equivalent to multiplicative scaling. Different transformations may
be applied to different analytical regions. Frequency shifts shall
be less than one-half the minimum instrumental linewidth, and must
be applied to all spectral data points in an analytical region. The
mathematical transformations may be retained for the analysis if
they are also applied to the appropriate analytical regions of all
sample spectra recorded, and if all original sample spectra are
digitally stored. Repeat sections 5.3, 5.4 (except the recording of
a sample spectrum), and 5.5 of this addendum to demonstrate that
these transformations lead to acceptable calculated concentration
uncertainties in all analytical regions.
6.0 Post-Analysis Evaluations
Estimate the overall accuracy of the analyses performed in
accordance with sections 5.1 through 5.6 of this addendum using the
procedures of sections 6.1 through 6.3 of this addendum.
6.1 Qualitatively Confirm the Assumed Matrix. Examine
each analytical region of the sample spectrum for spectral evidence
of unexpected or unidentified interferants. If found, identify the
interfering compounds (see Reference C for guidance) and add them
to the list of known interferants. Repeat the procedures of section
4 of this addendum to include the interferants in the uncertainty
calculations and analysis procedures. Verify that the MAU and FCU
values do not increase beyond acceptable levels for the application
requirements. Re-calculate the analyte concentrations (section 5.5
of this addendum) in the affected analytical regions.
6.2 Quantitatively Evaluate Fractional Model Uncertainty
(FMU). Perform the procedures of either section 6.2.1 or 6.2.2
of this addendum:
6.2.1 Using appendix I of this addendum, determine the
fractional model error (FMU) for each analyte.
6.2.2 Provide statistically determined uncertainties FMU for
each analyte which are equivalent to two standard deviations at the
95 percent confidence level. Such determinations, if employed, must
be based on mathematical examinations of the pertinent sample
spectra (not the reference spectra alone). Include in the report of
the analysis (see section 7.0 of this addendum) a complete
description of the determination of the concentration
uncertainties.
6.3 Estimate Overall Concentration Uncertainty (OCU).
Using appendix J of this addendum, determine the overall
concentration uncertainty (OCU) for each analyte. If the OCU is
larger than the required accuracy for any analyte, repeat sections
4 and 6 of this addendum.
7.0 Reporting Requirements [Documentation pertaining to virtually
all the procedures of sections 4, 5, and 6 will be required.
Software copies of reference spectra and sample spectra will be
retained for some minimum time following the actual testing.] 8.0
References
(A) Standard Practices for General Techniques of Infrared
Quantitative Analysis (American Society for Testing and Materials,
Designation E 168-88).
(B) The Coblentz Society Specifications for Evaluation of
Research Quality Analytical Infrared Reference Spectra (Class II);
Anal. Chemistry 47, 945A (1975); Appl. Spectroscopy 444, pp.
211-215, 1990.
(C) Standard Practices for General Techniques for Qualitative
Infrared Analysis, American Society for Testing and Materials,
Designation E 1252-88.
(D) “EPA Traceability Protocol for Assay and Certification of
Gaseous Calibration Standards,” U.S. Environmental Protection
Agency Publication No. EPA/600/R-93/224, December 1993.
Appendix A to Addendum to Method 320 - Definitions of Terms and
Symbols
A.1 Definitions of Terms. All terms used in this method
that are not defined below have the meaning given to them in the
CAA and in subpart A of this part.
Absorption band means a contiguous wavenumber region of a
spectrum (equivalently, a contiguous set of absorbance spectrum
data points) in which the absorbance passes through a maximum or a
series of maxima.
Absorption pathlength means the distance in a
spectrophotometer, measured in the direction of propagation of the
beam of radiant energy, between the surface of the specimen on
which the radiant energy is incident and the surface of the
specimen from which it is emergent.
Analytical region means a contiguous wavenumber region
(equivalently, a contiguous set of absorbance spectrum data points)
used in the quantitative analysis for one or more analytes.
Note:
The quantitative result for a single analyte may be based on
data from more than one analytical region.
Apodization means modification of the ILS function by
multiplying the interferogram by a weighing function whose
magnitude varies with retardation.
Background spectrum means the single beam spectrum
obtained with all system components without sample present.
Baseline means any line drawn on an absorption spectrum
to establish a reference point that represents a function of the
radiant power incident on a sample at a given wavelength.
Beers's law means the direct proportionality of the
absorbance of a compound in a homogeneous sample to its
concentration.
Calibration transfer standard (CTS) gas means a gas
standard of a compound used to achieve and/or demonstrate suitable
quantitative agreement between sample spectra and the reference
spectra; see section 4.5.1 of this addendum.
Compound means a substance possessing a distinct, unique
molecular structure.
Concentration (c) means the quantity of a compound
contained in a unit quantity of sample. The unit “ppm” (number, or
mole, basis) is recommended.
Concentration-pathlength product means the mathematical
product of concentration of the species and absorption pathlength.
For reference spectra, this is a known quantity; for sample
spectra, it is the quantity directly determined from Beer's law.
The units “centimeters-ppm” or “meters-ppm” are recommended.
Derivative absorption spectrum means a plot of rate of
change of absorbance or of any function of absorbance with respect
to wavelength or any function of wavelength.
Double beam spectrum means a transmission or absorbance
spectrum derived by dividing the sample single beam spectrum by the
background spectrum.
Note:
The term “double-beam” is used elsewhere to denote a spectrum in
which the sample and background interferograms are collected
simultaneously along physically distinct absorption paths. Here,
the term denotes a spectrum in which the sample and background
interferograms are collected at different times along the same
absorption path.
Fast Fourier transform (FFT) means a method of speeding
up the computation of a discrete FT by factoring the data into
sparse matrices containing mostly zeros.
Flyback means interferometer motion during which no data
are recorded.
Fourier transform (FT) means the mathematical process for
converting an amplitude-time spectrum to an amplitude-frequency
spectrum, or vice versa.
Fourier transform infrared (FTIR) spectrometer means an
analytical system that employs a source of mid-infrared radiation,
an interferometer, an enclosed sample cell of known absorption
pathlength, an infrared detector, optical elements that transfer
infrared radiation between components, and a computer system. The
time-domain detector response (interferogram) is processed by a
Fourier transform to yield a representation of the detector
response vs. infrared frequency.
Note:
When FTIR spectrometers are interfaced with other instruments, a
slash should be used to denote the interface; e.g., GC/FTIR;
HPCL/FTIR, and the use of FTIR should be explicit; i.e., FTIR not
IR.
Frequency, v means the number of cycles per unit
time.
Infrared means the portion of the electromagnetic
spectrum containing wavelengths from approximately 0.78 to 800
microns.
Interferogram, I(σ) means record of the modulated
component of the interference signal measured as a function of
retardation by the detector.
Interferometer means device that divides a beam of
radiant energy into two or more paths, generates an optical path
difference between the beams, and recombines them in order to
produce repetitive interference maxima and minima as the optical
retardation is varied.
Linewidth means the full width at half maximum of an
absorption band in units of wavenumbers (cm−1).
Mid-infrared means the region of the electromagnetic
spectrum from approximately 400 to 5000 cm−1.
Reference spectra means absorption spectra of gases with
known chemical compositions, recorded at a known absorption
pathlength, which are used in the quantitative analysis of gas
samples.
Retardation, σ means optical path difference between two
beams in an interferometer; also known as “optical path difference”
or “optical retardation.”
Scan means digital representation of the detector output
obtained during one complete motion of the interferometer's moving
assembly or assemblies.
Scaling means application of a multiplicative factor to
the absorbance values in a spectrum.
Single beam spectrum means Fourier-transformed
interferogram, representing the detector response vs.
wavenumber.
Note:
The term “single-beam” is used elsewhere to denote any spectrum
in which the sample and background interferograms are recorded on
the same physical absorption path; such usage differentiates such
spectra from those generated using interferograms recorded along
two physically distinct absorption paths (see “double-beam
spectrum” above). Here, the term applies (for example) to the two
spectra used directly in the calculation of transmission and
absorbance spectra of a sample.
Standard reference material means a reference material,
the composition or properties of which are certified by a
recognized standardizing agency or group.
Note:
The equivalent ISO term is “certified reference material.”
Transmittance, T means the ratio of radiant power
transmitted by the sample to the radiant power incident on the
sample. Estimated in FTIR spectroscopy by forming the ratio of the
single-beam sample and background spectra.
Wavenumber, v means the number of waves per unit
length.
Note:
The usual unit of wavenumber is the reciprocal centimeter, cm−1.
The wavenumber is the reciprocal of the wavelength, λ, when λ is
expressed in centimeters.
Zero-filling means the addition of zero-valued points to
the end of a measured interferogram.
Note:
Performing the FT of a zero-filled interferogram results in
correctly interpolated points in the computed spectrum.
A.2 Definitions of Mathematical Symbols. The symbols used
in equations in this protocol are defined as follows:
(1) A, absorbance = the logarithm to the base 10 of the
reciprocal of the transmittance (T).
(2) AAIim = band area of the i th analyte in the m th analytical
region, at the concentration (CLi) corresponding to the product of
its required detection limit (DLi) and analytical uncertainty limit
(AUi) .
(3) AAVim = average absorbance of the i th analyte in the m th
analytical region, at the concentration (CLi) corresponding to the
product of its required detection limit (DLi) and analytical
uncertainty limit (AUi).
(4) ASC, accepted standard concentration = the concentration
value assigned to a chemical standard.
(5) ASCPP, accepted standard concentration-pathlength product =
for a chemical standard, the product of the ASC and the sample
absorption pathlength. The units “centimeters-ppm” or “meters-ppm”
are recommended.
(6) AUi, analytical uncertainty limit = the maximum permissible
fractional uncertainty of analysis for the i th analyte
concentration, expressed as a fraction of the analyte concentration
determined in the analysis.
(7) AVTm = average estimated total absorbance in the m th
analytical region.
(8) CKWNk = estimated concentration of the k th known
interferant.
(9) CMAXi = estimated maximum concentration of the i th
analyte.
(10) CPOTj = estimated concentration of the j th potential
interferant.
(11) DLi, required detection limit = for the i th analyte, the
lowest concentration of the analyte for which its overall
fractional uncertainty (OFUi) is required to be less than the
analytical uncertainty limit (AUi).
(12) FCm = center wavenumber position of the m th analytical
region.
(13) FAUi, fractional analytical uncertainty = calculated
uncertainty in the measured concentration of the i th analyte
because of errors in the mathematical comparison of reference and
sample spectra.
(14) FCUi, fractional calibration uncertainty = calculated
uncertainty in the measured concentration of the i th analyte
because of errors in Beer's law modeling of the reference spectra
concentrations.
(15) FFLm = lower wavenumber position of the CTS absorption band
associated with the m th analytical region.
(16) FFUm = upper wavenumber position of the CTS absorption band
associated with the m th analytical region.
(17) FLm = lower wavenumber position of the m th analytical
region.
(18) FMUi, fractional model uncertainty = calculated uncertainty
in the measured concentration of the i th analyte because of errors
in the absorption model employed.
(19) FNL = lower wavenumber position of the CTS spectrum
containing an absorption band at least as narrow as the analyte
absorption bands.
(20) FNU = upper wavenumber position of the CTS spectrum
containing an absorption band at least as narrow as the analyte
absorption bands.
(21) FRUi, fractional reproducibility uncertainty = calculated
uncertainty in the measured concentration of the i th analyte
because of errors in the reproducibility of spectra from the FTIR
system.
(22) FUm = upper wavenumber position of the m th analytical
region.
(23) IAIjm = band area of the j th potential interferant in the
m th analytical region, at its expected concentration (CPOTj).
(24) IAVim = average absorbance of the i th analyte in the m th
analytical region, at its expected concentration (CPOTj).
(25) ISCi or k, indicated standard concentration = the
concentration from the computerized analytical program for a
single-compound reference spectrum for the i th analyte or k th
known interferant.
(26) kPa = kilo-Pascal (see Pascal).
(27) LS′ = estimated sample absorption pathlength.
(28) LR = reference absorption pathlength.
(29) LS = actual sample absorption pathlength.
(30) MAUi = mean of the MAUim over the appropriate analytical
regions.
(31) MAUim, minimum analyte uncertainty = the calculated minimum
concentration for which the analytical uncertainty limit (AUi) in
the measurement of the i th analyte, based on spectral data in the
m th analytical region, can be maintained.
(32) MIUj = mean of the MIUjm over the appropriate analytical
regions.
(33) MIUjm, minimum interferant uncertainty = the calculated
minimum concentration for which the analytical uncertainty limit
CPOTj/20 in the measurement of the j th interferant, based on
spectral data in the m th analytical region, can be maintained.
(34) MIL, minimum instrumental linewidth = the minimum linewidth
from the FTIR system, in wavenumbers.
Note:
The MIL of a system may be determined by observing an absorption
band known (through higher resolution examinations) to be narrower
than indicated by the system. The MIL is fundamentally limited by
the retardation of the interferometer, but is also affected by
other operational parameters (e.g., the choice of apodization).
(35) Ni = number of analytes.
(36) Nj = number of potential interferants.
(37) Nk = number of known interferants.
(38) Nscan = the number of scans averaged to obtain an
interferogram.
(39) OFUi = the overall fractional uncertainty in an analyte
concentration determined in the analysis (OFUi = MAX[FRUi, FCUi,
FAUi, FMUi]).
(40) Pascal (Pa) = metric unit of static pressure, equal to one
Newton per square meter; one atmosphere is equal to 101,325 Pa;
1/760 atmosphere (one Torr, or one millimeter Hg) is equal to
133.322 Pa.
(41) Pmin = minimum pressure of the sampling system during the
sampling procedure.
(42) PS′ = estimated sample pressure.
(43) PR = reference pressure.
(44) PS = actual sample pressure.
(45) RMSSm = measured noise level of the FTIR system in the m th
analytical region.
(46) RMSD, root mean square difference = a measure of accuracy
determined by the following equation:

Where: n
= the number of observations for which the accuracy is determined.
ei = the difference between a measured value of a property and its
mean value over the n observations. Note:
The RMSD value “between a set of n contiguous absorbance values
(Ai) and the mean of the values” (AM) is defined as
(47) RSAi = the (calculated) final concentration of the i th
analyte.
(48) RSIk = the (calculated) final concentration of the k th
known interferant.
(49) tscan, scan time = time used to acquire a single scan, not
including flyback.
(50) tS, signal integration period = the period of time over
which an interferogram is averaged by addition and scaling of
individual scans. In terms of the number of scans Nscan and scan
time tscan, tS = Nscantscan.
(51) tSR = signal integration period used in recording reference
spectra.
(52) tSS = signal integration period used in recording sample
spectra.
(53) TR = absolute temperature of gases used in recording
reference spectra.
(54) TS = absolute temperature of sample gas as sample spectra
are recorded.
(55) TP, Throughput = manufacturer's estimate of the fraction of
the total infrared power transmitted by the absorption cell and
transfer optics from the interferometer to the detector.
(56) VSS = volume of the infrared absorption cell, including
parts of attached tubing.
(57) Wik = weight used to average over analytical regions k for
quantities related to the analyte i; see appendix D of this
addendum.
Appendix B to Addendum to Method 320 - Identifying Spectral
Interferants B.1 General
B.1.1 Assume a fixed absorption pathlength equal to the value
LS′.
B.1.2 Use band area calculations to compare the relative
absorption strengths of the analytes and potential interferants. In
the m th analytical region (FLm to FUm), use either rectangular or
trapezoidal approximations to determine the band areas described
below (see Reference A, sections A.3.1 through A.3.3). Document any
baseline corrections applied to the spectra.
B.1.3 Use the average total absorbance of the analytes and
potential interferants in each analytical region to determine
whether the analytical region is suitable for analyte concentration
determinations.
Note:
The average absorbance in an analytical region is the band area
divided by the width of the analytical region in wavenumbers. The
average total absorbance in an analytical region is the sum of the
average absorbances of all analytes and potential interferants.
B.2 Calculations
B.2.1 Prepare spectral representations of each analyte at the
concentration CLi = (DLi)(AUi), where DLi is the required detection
limit and AUi is the maximum permissible analytical uncertainty.
For the m th analytical region, calculate the band area (AAIim) and
average absorbance (AAVim) from these scaled analyte spectra.
B.2.2 Prepare spectral representations of each potential
interferant at its expected concentration (CPOTj). For the m th
analytical region, calculate the band area (IAIjm) and average
absorbance (IAVjm) from these scaled potential interferant
spectra.
B.2.3 Repeat the calculation for each analytical region, and
record the band area results in matrix form as indicated in Figure
B.1.
B.2.4 If the band area of any potential interferant in an
analytical region is greater than the one-half the band area of any
analyte (i.e., IAIjm >0.5 AAIim for any pair ij and any m),
classify the potential interferant as a known interferant. Label
the known interferants k = 1 to K. Record the results in matrix
form as indicated in Figure B.2.
B.2.5 Calculate the average total absorbance (AVTm) for each
analytical region and record the values in the last row of the
matrix described in Figure B.2. Any analytical region where AVTm
>2.0 is unsuitable.

Appendix
C to Addendum to Method 320 - Estimating Noise Levels C.1 General
C.1.1 The root-mean-square (RMS) noise level is the standard
measure of noise in this addendum. The RMS noise level of a
contiguous segment of a spectrum is defined as the RMS difference
(RMSD) between the absorbance values which form the segment and the
mean value of that segment (see appendix A of this addendum).
C.1.2 The RMS noise value in double-beam absorbance spectra is
assumed to be inversely proportional to: (a) the square root of the
signal integration period of the sample single beam spectra from
which it is formed, and (b) the total infrared power transmitted
through the interferometer and absorption cell.
C.1.3 Practically, the assumption of C.1.2 allows the RMS noise
level of a complete system to be estimated from the quantities
described in sections C.1.3.1 through C.1.3.4:
C.1.3.1 RMSMAN, the noise level of the system (in absorbance
units), without the absorption cell and transfer optics, under
those conditions necessary to yield the specified minimum
instrumental linewidth, e.g., Jacquinot stop size.
C.1.3.2 tMAN, the manufacturer's signal integration time used to
determine RMSMAN.
C.1.3.3 tSS, the signal integration time for the analyses.
C.1.3.4 TP, the manufacturer's estimate of the fraction of the
total infrared power transmitted by the absorption cell and
transfer optics from the interferometer to the detector.
C.2 Calculations
C.2.1 Obtain the values of RMSMAN, tMAN, and TP from the
manufacturers of the equipment, or determine the noise level by
direct measurements with the completely constructed system proposed
in section 4 of this addendum.
C.2.2 Calculate the noise value of the system (RMSEST) using
equation C.1.

Appendix
D to Addendum to Method 320 - Estimating Minimum Concentration
Measurement Uncertainties (MAU and MIU) D.1 General
Estimate the minimum concentration measurement uncertainties for
the i th analyte (MAUi) and j th interferant (MIUj) based on the
spectral data in the m th analytical region by comparing the
analyte band area in the analytical region (AAIim) and estimating
or measuring the noise level of the system (RMSEST or RMSSM).
Note:
For a single analytical region, the MAU or MIU value is the
concentration of the analyte or interferant for which the band area
is equal to the product of the analytical region width (in
wavenumbers) and the noise level of the system (in absorbance
units). If data from more than one analytical region are used in
the determination of an analyte concentration, the MAU or MIU is
the mean of the separate MAU or MIU values calculated for each
analytical region.
D.2 Calculations
D.2.1 For each analytical region, set RMS = RMSSM if measured
(appendix G of this addendum), or set RMS = RMSEST if estimated
(appendix C of this addendum).
D.2.2 For each analyte associated with the analytical region,
calculate MAUim using equation D.1,
D.2.3 If only the m th analytical region is used to calculate
the concentration of the i th analyte, set MAUi = MAUim.
D.2.4 If more than one analytical region is used to calculate
the concentration of the i th analyte, set MAUi equal to the
weighted mean of the appropriate MAUim values calculated above; the
weight for each term in the mean is equal to the fraction of the
total wavenumber range used for the calculation represented by each
analytical region. Mathematically, if the set of analytical regions
employed is [m′], then the MAU for each analytical region is given
by equation D.2.

where the
weight Wik is defined for each term in the sum as
D.2.5 Repeat sections D.2.1 through D.2.4 of this appendix to
calculate the analogous values MIUj for the interferants j = 1 to
J. Replace the value (AUi) (DLi) in equation D.1 with CPOTj/20;
replace the value AAIim in equation D.1 with IAIjm.
Appendix E to Addendum to Method 320 - Determining Fractional
Reproducibility Uncertainties (FRU) E.1 General
To estimate the reproducibility of the spectroscopic results of
the system, compare the CTS spectra recorded before and after
preparing the reference spectra. Compare the difference between the
spectra to their average band area. Perform the calculation for
each analytical region on the portions of the CTS spectra
associated with that analytical region.
E.2 Calculations
E.2.1 The CTS spectra {R1} consist of N spectra, denoted by S1i,
i = 1, N. Similarly, the CTS spectra {R2} consist of N spectra,
denoted by S2i, i = 1, N. Each Ski is the spectrum of a single
compound, where i denotes the compound and k denotes the set {} of
which Ski is a member. Form the spectra S3 according to S3i =
S2i−S1i for each i. Form the spectra S4 according to S4i = [S2i +
S1i]/2 for each i.
E.2.2 Each analytical region m is associated with a portion of
the CTS spectra S2i and S1i, for a particular i, with lower and
upper wavenumber limits FFLm and FFUm, respectively.
E.2.3 For each m and the associated i, calculate the band area
of S4i in the wavenumber range FFUm to FFLm. Follow the guidelines
of section B.1.2 of this addendum for this band area calculation.
Denote the result by BAVm.
E.2.4 For each m and the associated i, calculate the RMSD of S3i
between the absorbance values and their mean in the wavenumber
range FFUm to FFLm. Denote the result by SRMSm.
E.2.5 For each analytical region m, calculate FMm using equation
E.1,
E.2.6 If only the m th analytical region is used to calculate
the concentration of the i th analyte, set FRUi = FMm.
E.2.7 If a number pi of analytical regions are used to calculate
the concentration of the i th analyte, set FRUi equal to the
weighted mean of the appropriate FMm values calculated according to
section E.2.5. Mathematically, if the set of analytical regions
employed is {m′}, then FRUi is given by equation E.2,

where the
Wik are calculated as described in appendix D of this addendum.
Appendix F of Addendum to Method 320 - Determining Fractional
Calibration Uncertainties (FCU) F.1 General
F.1.1 The concentrations yielded by the computerized analytical
program applied to each single-compound reference spectrum are
defined as the indicated standard concentrations (ISC's). The ISC
values for a single compound spectrum should ideally equal the
accepted standard concentration (ASC) for one analyte or
interferant, and should ideally be zero for all other compounds.
Variations from these results are caused by errors in the ASC
values, variations from the Beer's law (or modified Beer's law)
model used to determine the concentrations, and noise in the
spectra. When the first two effects dominate, the systematic nature
of the errors is often apparent and the analyst shall take steps to
correct them.
F.1.2 When the calibration error appears non-systematic, apply
the procedures of sections F.2.1 through F.2.3 of this appendix to
estimate the fractional calibration uncertainty (FCU) for each
compound. The FCU is defined as the mean fractional error between
the ASC and the ISC for all reference spectra with non-zero ASC for
that compound. The FCU for each compound shall be less than the
required fractional uncertainty specified in section 4.1 of this
addendum.
F.1.3 The computerized analytical programs shall also be
required to yield acceptably low concentrations for compounds with
ISC = 0 when applied to the reference spectra. The ISC of each
reference spectrum for each analyte or interferant shall not exceed
that compound's minimum measurement uncertainty (MAU or MIU).
F.2 Calculations
F.2.1 Apply each analytical program to each reference spectrum.
Prepare a similar table to that in Figure F.1 to present the ISC
and ASC values for each analyte and interferant in each reference
spectrum. Maintain the order of reference file names and compounds
employed in preparing Figure F.1.
F.2.2 For all reference spectra in Figure F.1, verify that the
absolute values of the ISC's are less than the compound's MAU (for
analytes) or MIU (for interferants).
F.2.3 For each analyte reference spectrum, calculate the
quantity (ASC-ISC)/ASC. For each analyte, calculate the mean of
these values (the FCUi for the i th analyte) over all reference
spectra. Prepare a similar table to that in Figure F.2 to present
the FCUi and analytical uncertainty limit (AUi) for each
analyte.
Figure F.1 - Presentation of Accepted
Standard Concentrations (ASC's) and Indicated Standard
Concentrations (ISC's)
Compound name |
Reference spectrum file
name |
ASC (ppm) |
ISC (ppm) |
|
|
|
Analytes
Interferants |
|
|
|
i = 1 I |
|
|
|
j = 1 J |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Figure F.2 - Presentation of Fractional
Calibration Uncertainties (FCU's) and Analytical Uncertainties
(AU's)
Analyte name |
FCU (%) |
AU (%) |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Appendix G to Addendum to Method 320 - Measuring Noise Levels G.1
General
The root-mean-square (RMS) noise level is the standard measure
of noise. The RMS noise level of a contiguous segment of a spectrum
is the RMSD between the absorbance values that form the segment and
the mean value of the segment (see appendix A of this
addendum).
G.2 Calculations
G.2.1 Evacuate the absorption cell or fill it with UPC grade
nitrogen at approximately one atmosphere total pressure.
G.2.2 Record two single beam spectra of signal integration
period tSS.
G.2.3 Form the double beam absorption spectrum from these two
single beam spectra, and calculate the noise level RMSSm in the M
analytical regions.
Appendix H of Addendum to Method 320 - Determining Sample
Absorption Pathlength (LS) and Fractional Analytical Uncertainty
(FAU) H.1 General
Reference spectra recorded at absorption pathlength (LR), gas
pressure (PR), and gas absolute temperature (TR) may be used to
determine analyte concentrations in samples whose spectra are
recorded at conditions different from that of the reference
spectra, i.e., at absorption pathlength (LS), absolute temperature
(TS), and pressure (PS). This appendix describes the calculations
for estimating the fractional uncertainty (FAU) of this practice.
It also describes the calculations for determining the sample
absorption pathlength from comparison of CTS spectra, and for
preparing spectra for further instrumental and procedural
checks.
H.1.1 Before sampling, determine the sample absorption
pathlength using least squares analysis. Determine the ratio LS/LR
by comparing the spectral sets {R1} and {R3}, which are recorded
using the same CTS at LS and LR, and TS and TR, but both at PR.
H.1.2 Determine the fractional analysis uncertainty (FAU) for
each analyte by comparing a scaled CTS spectral set, recorded at
LS, TS, and PS, to the CTS reference spectra of the same gas,
recorded at LR, TR, and PR. Perform the quantitative comparison
after recording the sample spectra, based on band areas of the
spectra in the CTS absorbance band associated with each
analyte.
H.2 Calculations
H.2.1 Absorption Pathlength Determination. Perform and
document separate linear baseline corrections to each analytical
region in the spectral sets {R1} and {R3}. Form a one-dimensional
array AR containing the absorbance values from all segments of {R1}
that are associated with the analytical regions; the members of the
array are ARi, i = 1, n. Form a similar one-dimensional array AS
from the absorbance values in the spectral set {R3}; the members of
the array are ASi, i = 1, n. Based on the model AS = rAR + E,
determine the least-squares estimate of r, the value of r which
minimizes the square error E 2. Calculate the sample absorption
pathlength, LS, using equation H.1,
H.2.2 Fractional Analysis Uncertainty. Perform and
document separate linear baseline corrections to each analytical
region in the spectral sets {R1} and {R4}. Form the arrays AS and
AR as described in section H.2.1 of this appendix, using values
from {R1} to form AR, and values from {R4} to form AS. Calculate
NRMSE and IAAV using equations H.2 and H.3,
The fractional analytical uncertainty, FAU, is given by equation
H.4,

Appendix
I to Addendum to Method 320 - Determining Fractional Model
Uncertainties (FMU) I.1 General
To prepare analytical programs for FTIR analyses, the sample
constituents must first be assumed. The calculations in this
appendix, based upon a simulation of the sample spectrum, shall be
used to verify the appropriateness of these assumptions. The
simulated spectra consist of the sum of single compound reference
spectra scaled to represent their contributions to the sample
absorbance spectrum; scaling factors are based on the indicated
standard concentrations (ISC) and measured (sample) analyte and
interferant concentrations, the sample and reference absorption
pathlengths, and the sample and reference gas pressures. No
band-shape correction for differences in the temperature of the
sample and reference spectra gases is made; such errors are
included in the FMU estimate. The actual and simulated sample
spectra are quantitatively compared to determine the fractional
model uncertainty; this comparison uses the reference spectra band
areas and residuals in the difference spectrum formed from the
actual and simulated sample spectra.
I.2 Calculations
I.2.1 For each analyte (with scaled concentration RSAi), select
a reference spectrum SAi with indicated standard concentration
ISCi. Calculate the scaling factors, RAi, using equation I.1,

Form the
spectra SACi by scaling each SAi by the factor RAi.
I.2.2 For each interferant, select a reference spectrum SIk with
indicated standard concentration ISCk. Calculate the scaling
factors, RIk, using equation I.2,

Form the
spectra SICk by scaling each SIk by the factor RIk.
I.2.3 For each analytical region, determine by visual inspection
which of the spectra SACi and SICk exhibit absorbance bands within
the analytical region. Subtract each spectrum SACi and SICk
exhibiting absorbance from the sample spectrum SS to form the
spectrum SUBS. To save analysis time and to avoid the introduction
of unwanted noise into the subtracted spectrum, it is recommended
that the calculation be made (1) only for those spectral data
points within the analytical regions, and (2) for each analytical
region separately using the original spectrum SS.
I.2.4 For each analytical region m, calculate the RMSD of SUBS
between the absorbance values and their mean in the region FFUm to
FFLm. Denote the result by RMSSm.
I.2.5 For each analyte i, calculate FMm, using equation I.3,

for each
analytical region associated with the analyte.
I.2.6 If only the m th analytical region is used to calculate
the concentration of the i th analyte, set FMUi = FMm.
I.2.7 If a number of analytical regions are used to calculate
the concentration of the i th analyte, set FMi equal to the
weighted mean of the appropriate FMm values calculated using
equation I-3. Mathematically, if the set of analytical regions
employed is {m′}, then the fractional model uncertainty, FMU, is
given by equation I.4,

where Wik
is calculated as described in appendix D of this addendum. Appendix
J of Addendum to Method 320 - Determining Overall Concentration
Uncertainties (OCU)
The calculations in this addendum estimate the measurement
uncertainties for various FTIR measurements. The lowest possible
overall concentration uncertainty (OCU) for an analyte is its MAU
value, which is an estimate of the absolute concentration
uncertainty when spectral noise dominates the measurement error.
However, if the product of the largest fractional concentration
uncertainty (FRU, FCU, FAU, or FMU) and the measured concentration
of an analyte exceeds the MAU for the analyte, then the OCU is this
product. In mathematical terms, set OFUi = MAX{FRUi, FCUi, FAUi,
FMUi} and OCUi = MAX{RSAi*OFUi, MAUi}.
Test Method 321 - Measurement of Gaseous Hydrogen Chloride
Emissions At Portland Cement Kilns by Fourier Transform Infrared
(FTIR) Spectroscopy 1.0 Introduction
This method should be performed by those persons familiar with
the operation of Fourier Transform Infrared (FTIR) instrumentation
in the application to source sampling. This document describes the
sampling procedures for use in the application of FTIR spectrometry
for the determination of vapor phase hydrogen chloride (HCl)
concentrations both before and after particulate matter control
devices installed at portland cement kilns. A procedure for analyte
spiking is included for quality assurance. This method is
considered to be self validating provided that the requirements
listed in section 9 of this method are followed. The analytical
procedures for interpreting infrared spectra from emission
measurements are described in the “Protocol For The Use of
Extractive Fourier Transform Infrared (FTIR) Spectrometry in
Analyses of Gaseous Emissions From Stationary Industrial Sources”,
included as an addendum to proposed Method 320 of this appendix
(hereafter referred to as the “FTIR Protocol)”. References 1 and 2
describe the use of FTIR spectrometry in field measurements. Sample
transport presents the principal difficulty in directly measuring
HCl emissions. This identical problem must be overcome by any
extractive measurement method. HCl is reactive and water soluble.
The sampling system must be adequately designed to prevent sample
condensation in the system.
1.1 Scope and Application
This method is specifically designed for the application of FTIR
Spectrometry in extractive measurements of gaseous HCl
concentrations in portland cement kiln emissions.
1.2 Applicability
This method applies to the measurement of HCl [CAS No.
7647-01-0]. This method can be applied to the determination of HCl
concentrations both before and after particulate matter control
devices installed at portland cement manufacturing facilities. This
method applies to either continuous flow through measurement (with
isolated sample analysis) or grab sampling (batch analysis). HCl is
measured using the mid-infrared spectral region for analysis (about
400 to 4000 cm−1 or 25 to 2.5 µm). Table 1 lists the suggested
analytical region for quantification of HCl taking the interference
from water vapor into consideration.
Table 1 - Example Analytical Region for
HCl
Compound |
Analytical
region
(cm−1) |
Potential
interferants |
Hydrogen
chloride |
2679-2840 |
Water. |
1.3 Method Range and Sensitivity
1.3.1 The analytical range is determined by the instrumental
design and the composition of the gas stream. For practical
purposes there is no upper limit to the range because the
pathlength may be reduced or the sample may be diluted. The lower
detection range depends on (1) the absorption coefficient of the
compound in the analytical frequency region, (2) the spectral
resolution, (3) the interferometer sampling time, (4) the detector
sensitivity and response, and (5) the absorption pathlength.
1.3.2 The practical lower quantification range is usually higher
than that indicated by the instrument performance in the
laboratory, and is dependent upon (1) the presence of interfering
species in the exhaust gas (notably H2O), (2) the optical alignment
of the gas cell and transfer optics, and (3) the quality of the
reflective surfaces in the cell (cell throughput). Under typical
test conditions (moisture content of up to 30 percent, 10 meter
absorption path length, liquid nitrogen-cooled IR detector, 0.5
cm−1 resolution, and an interferometer sampling time of 60 seconds)
a typical lower quantification range for HCl is 0.1 to 1.0 ppm.
1.4 Data Quality Objectives
1.4.1 In designing or configuring the analytical system, data
quality is determined by measuring of the root mean square
deviation (RMSD) of the absorbance values within a chosen spectral
(analytical) region. The RMSD provides an indication of the
signal-to-noise ratio (S/N) of the spectral baseline. Appendix D of
the FTIR Protocol (the addendum to Method 320 of this appendix)
presents a discussion of the relationship between the RMSD, lower
detection limit, DLi, and analytical uncertainty, AUi. It is
important to consider the target analyte quantification limit when
performing testing with FTIR instrumentation, and to optimize the
system to achieve the desired detection limit.
1.4.2 Data quality is determined by measuring the root mean
square (RMS) noise level in each analytical spectral region
(appendix C of the FTIR Protocol). The RMS noise is defined as the
root mean square deviation (RMSD) of the absorbance values in an
analytical region from the mean absorbance value in the same
region. Appendix D of the FTIR Protocol defines the minimum
analyte uncertainty (MAU), and how the RMSD is used to calculate
the MAU. The MAUim is the minimum concentration of the ith analyte
in the mth analytical region for which the analytical uncertainty
limit can be maintained. Table 2 presents example values of AU and
MAU using the analytical region presented in Table 1.
Table 2 - Example Pre-Test Protocol
Calculations for Hydrogen Chloride
|
HCl |
Reference
concentration (ppm-meters)/K |
11.2 |
Reference Band
area |
2.881 |
DL
(ppm-meters)/K |
0.1117 |
AU |
0.2 |
CL (DL × AU) |
0.02234 |
FL (cm−1) |
2679.83 |
FU (cm−1) |
2840.93 |
FC (cm−1) |
2760.38 |
AAI
(ppm-meters)/K |
0.06435 |
RMSD |
2.28E-03 |
MAU
(ppm-meters)/K |
1.28E-01 |
MAU ppm at 22
meters and 250 °F |
.0.2284 |
2.0 Summary of Method
2.1 Principle
See Method 320 of this appendix. HCl can also undergo rotation
transitions by absorbing energy in the far-infrared spectral
region. The rotational transitions are superimposed on the
vibrational fundamental to give a series of lines centered at the
fundamental vibrational frequency, 2885 cm- 1. The frequencies of
absorbance and the pattern of rotational/vibrational lines are
unique to HCl. When this distinct pattern is observed in an
infrared spectrum of an unknown sample, it unequivocally identifies
HCl as a component of the mixture. The infrared spectrum of HCl is
very distinctive and cannot be confused with the spectrum of any
other compound. See Reference 6.
2.2 Sampling and Analysis. See Method 320 of this
appendix.
2.3 Operator Requirements. The analyst must have
knowledge of spectral patterns to choose an appropriate absorption
path length or determine if sample dilution is necessary. The
analyst should also understand FTIR instrument operation well
enough to choose instrument settings that are consistent with the
objectives of the analysis.
3.0 Definitions
See appendix A of the FTIR Protocol.
4.0 Interferences
This method will not measure HCl under conditions: (1) where the
sample gas stream can condense in the sampling system or the
instrumentation, or (2) where a high moisture content sample
relative to the analyte concentrations imparts spectral
interference due to the water vapor absorbance bands. For measuring
HCl the first (sampling) consideration is more critical. Spectral
interference from water vapor is not a significant problem except
at very high moisture levels and low HCl concentrations.
4.1 Analytical Interferences. See Method 320 of this
appendix.
4.1.1 Background Interferences. See Method 320 of this
appendix.
4.1.2 Spectral interferences. Water vapor can present
spectral interference for FTIR gas analysis of HCl. Therefore, the
water vapor in the spectra of kiln gas samples must be accounted
for. This means preparing at least one spectrum of a water vapor
sample where the moisture concentration is close to that in the
kiln gas.
4.2 Sampling System Interferences. The principal sampling
system interferant for measuring HCl is water vapor. Steps must be
taken to ensure that no condensation forms anywhere in the probe
assembly, sample lines, or analytical instrumentation. Cold spots
anywhere in the sampling system must be avoided. The extent of
sampling system bias in the FTIR analysis of HCl depends on
concentrations of potential interferants, moisture content of the
gas stream, temperature of the gas stream, temperature of sampling
system components, sample flow rate, and reactivity of HCl with
other species in the gas stream (e.g., ammonia). For measuring HCl
in a wet gas stream the temperatures of the gas stream, sampling
components, and the sample flow rate are of primary importance.
Analyte spiking with HCl is performed to demonstrate the integrity
of the sampling system for transporting HCl vapor in the flue gas
to the FTIR instrument. See section 9 of this method for a complete
description of analyte spiking.
5.0 Safety
5.1 Hydrogen chloride vapor is corrosive and can cause
irritation or severe damage to respiratory system, eyes and skin.
Exposure to this compound should be avoided.
5.2 This method may involve sampling at locations having high
positive or negative pressures, or high concentrations of hazardous
or toxic pollutants, and can not address all safety problems
encountered under these diverse sampling conditions. It is the
responsibility of the tester(s) to ensure proper safety and health
practices, and to determine the applicability of regulatory
limitations before performing this test method. Leak-check
procedures are outlined in section 8.2 of Method 320 of this
appendix.
6.0 Equipment and Supplies Note:
Mention of trade names or specific products does not constitute
endorsement by the Environmental Protection Agency.
6.1 FTIR Spectrometer and Detector. An FTIR Spectrometer
system (interferometer, transfer optics, gas cell and detector)
having the capability of measuring HCl to the predetermined minimum
detectable level required (see section 4.1.3 of the FTIR Protocol).
The system must also include an accurate means to control and/or
measure the temperature of the FTIR gas analysis cell, and a
personal computer with compatible software that provides real-time
updates of the spectral profile during sample and spectral
collection.
6.2 Pump. Capable of evacuating the FTIR cell volume to 1
Torr (133.3 Pascals) within two minutes (for batch sample
analysis).
6.3 Mass Flow Meters/Controllers. To accurately measure
analyte spike flow rate, having the appropriate calibrated range
and a stated accuracy of ±2 percent of the absolute measurement
value. This device must be calibrated with the major component of
the calibration/spike gas (e.g., nitrogen) using an NIST traceable
bubble meter or equivalent. Single point calibration checks should
be performed daily in the field. When spiking HCl, the mass flow
meter/controller should be thoroughly purged before and after
introduction of the gas to prevent corrosion of the interior
parts.
6.4 Polytetrafluoroethane tubing. Diameter and length
suitable to connect cylinder regulators.
6.5 Stainless Steel tubing. Type 316 of appropriate
length and diameter for heated connections.
6.6 Gas Regulators. Purgeable HCl regulator.
6.7 Pressure Gauge. Capable of measuring pressure from 0
to 1000 Torr (133.3 Pa = 1 Torr) within ±5 percent.
6.8 Sampling Probe. Glass, stainless steel or other
appropriate material of sufficient length and physical integrity to
sustain heating, prevent adsorption of analytes and capable of
reaching gas sampling point.
6.9 Sampling Line. Heated 180 °C (360 °F) and fabricated
of either stainless steel, polytetrafluoroethane or other material
that prevents adsorption of HCl and transports effluent to
analytical instrumentation. The extractive sample line must have
the capability to transport sample gas to the analytical components
as well as direct heated calibration spike gas to the calibration
assembly located at the sample probe. It is important to minimize
the length of heated sample line.
6.10 Particulate Filters. A sintered stainless steel
filter rated at 20 microns or greater may be placed at the inlet of
the probe (for removal of large particulate matter). A heated
filter (Balston or equivalent) rated at 1 micron is necessary for
primary particulate matter removal, and shall be placed immediately
after the heated probe. The filter/filter holder temperature should
be maintained at 180 °C (360 °F).
6.11 Calibration/Analyte Spike Assembly. A heated
three-way valve assembly (or equivalent) to introduce surrogate
spikes into the sampling system at the outlet of the probe before
the primary particulate filter.
6.12 Sample Extraction Pump. A leak-free heated head pump
(KNF Neuberger or equivalent) capable of extracting sample effluent
through entire sampling system at a rate which prevents analyte
losses and minimizes analyzer response time. The pump should have a
heated by-pass and may be placed either before the FTIR instrument
or after. If the sample pump is located upstream of the FTIR
instrument, it must be fabricated from materials non-reactive to
HCl. The sampling system and FTIR measurement system shall allow
the operator to obtain at least six sample spectra during a
one-hour period.
6.13 Barometer. For measurement of barometric
pressure.
6.14 Gas Sample Manifold. A distribution manifold having
the capabilities listed in sections 6.14.1 through 6.14.4;
6.14.1 Delivery of calibration gas directly to the analytical
instrumentation;
6.14.2 Delivery of calibration gas to the sample probe (system
calibration or analyte spike) via a heated traced sample line;
6.14.3 Delivery of sample gas (kiln gas, spiked kiln gas, or
system calibrations) to the analytical instrumentation;
6.14.4 Delivery (optional) of a humidified nitrogen sample
stream.
6.15 Flow Measurement Device. Type S Pitot tube (or
equivalent) and Magnahelic set for measurement of volumetric flow
rate.
7.0 Reagents and Standards
HCl can be purchased in a standard compressed gas cylinder. The
most stable HCl cylinder mixture available has a concentration
certified at ±5 percent. Such a cylinder is suitable for performing
analyte spiking because it will provide reproducible samples. The
stability of the cylinder can be monitored over time by
periodically performing direct FTIR analysis of cylinder samples.
It is recommended that a 10-50 ppm cylinder of HCl be prepared
having from 2-5 ppm SF6 as a tracer compound. (See sections 7.1
through 7.3 of Method 320 of this appendix for a complete
description of the use of existing HCl reference spectra. See
section 9.1 of Method 320 of this appendix for a complete
discussion of standard concentration selection.)
8.0 Sample Collection, Preservation and Storage
See also Method 320 of this appendix.
8.1 Pretest. A screening test is ideal for obtaining
proper data that can be used for preparing analytical program
files. Information from literature surveys and source personnel is
also acceptable. Information about the sampling location and gas
stream composition is required to determine the optimum sampling
system configuration for measuring HCl. Determine the percent
moisture of the kiln gas by Method 4 of appendix A to part 60 of
this chapter or by performing a wet bulb/dry bulb measurement.
Perform a preliminary traverse of the sample duct or stack and
select the sampling point(s). Acquire an initial spectrum and
determine the optimum operational pathlength of the instrument.
8.2 Leak-Check. See Method 320 of this appendix, section
8.2 for direction on performing leak-checks.
8.3 Background Spectrum. See Method 320 of this appendix,
section 8.5 for direction in background spectral acquisition.
8.4 Pre-Test Calibration Transfer Standard (Direct Instrument
Calibration). See Method 320 of this appendix, section 8.3 for
direction in CTS spectral acquisition.
8.5 Pre-Test System Calibration. See Method 320 of this
appendix, sections 8.6.1 through 8.6.2 for direction in performing
system calibration.
8.6 Sampling
8.6.1 Extractive System. An extractive system maintained
at 180 °C (360 °F) or higher which is capable of directing a total
flow of at least 12 L/min to the sample cell is required
(References 1 and 2). Insert the probe into the duct or stack at a
point representing the average volumetric flow rate and 25 percent
of the cross sectional area. Co-locate an appropriate flow
monitoring device with the sample probe so that the flow rate is
recorded at specified time intervals during emission testing (e.g.,
differential pressure measurements taken every 10 minutes during
each run).
8.6.2 Batch Samples. Evacuate the absorbance cell to 5
Torr (or less) absolute pressure before taking first sample. Fill
the cell with kiln gas to ambient pressure and record the infrared
spectrum, then evacuate the cell until there is no further evidence
of infrared absorption. Repeat this procedure, collecting a total
of six separate sample spectra within a 1-hour period.
8.6.3 Continuous Flow Through Sampling. Purge the FTIR
cell with kiln gas for a time period sufficient to equilibrate the
entire sampling system and FTIR gas cell. The time required is a
function of the mechanical response time of the system (determined
by performing the system calibration with the CTS gas or
equivalent), and by the chemical reactivity of the target analytes.
If the effluent target analyte concentration is not variable,
observation of the spectral up-date of the flowing gas sample
should be performed until equilibration of the sample is achieved.
Isolate the gas cell from the sample flow by directing the purge
flow to vent. Record the spectrum and pressure of the sample gas.
After spectral acquisition, allow the sample gas to purge the cell
with at least three volumes of kiln gas. The time required to
adequately purge the cell with the required volume of gas is a
function of (1) cell volume, (2) flow rate through the cell, and
(3) cell design. It is important that the gas introduction and vent
for the FTIR cell provides a complete purge through the cell.
8.6.4 Continuous Sampling. In some cases it is possible
to collect spectra continuously while the FTIR cell is purged with
sample gas. The sample integration time, tss, the sample flow rate
through the gas cell, and the sample integration time must be
chosen so that the collected data consist of at least 10 spectra
with each spectrum being of a separate cell volume of flue gas.
Sampling in this manner may only be performed if the native source
analyte concentrations do not affect the test results.
8.7 Sample Conditioning
8.7.1 High Moisture Sampling. Kiln gas emitted from wet
process cement kilns may contain 3- to 40 percent moisture. Zinc
selenide windows or the equivalent should be used when attempting
to analyze hot/wet kiln gas under these conditions to prevent
dissolution of water soluble window materials (e.g., KBr).
8.7.2 Sample Dilution. The sample may be diluted using an
in-stack dilution probe, or an external dilution device provided
that the sample is not diluted below the instrument's
quantification range. As an alternative to using a dilution probe,
nitrogen may be dynamically spiked into the effluent stream in the
same manner as analyte spiking. A constant dilution rate shall be
maintained throughout the measurement process. It is critical to
measure and verify the exact dilution ratio when using a dilution
probe or the nitrogen spiking approach. Calibrating the system with
a calibration gas containing an appropriate tracer compound will
allow determination of the dilution ratio for most measurement
systems. The tester shall specify the procedures used to determine
the dilution ratio, and include these calibration results in the
report.
8.8 Sampling QA, Data Storage and Reporting. See the FTIR
Protocol. Sample integration times shall be sufficient to achieve
the required signal-to-noise ratio, and all sample spectra should
have unique file names. Two copies of sample interferograms and
processed spectra will be stored on separate computer media. For
each sample spectrum the analyst must document the sampling
conditions, the sampling time (while the cell was being filled),
the time the spectrum was recorded, the instrumental conditions
(path length, temperature, pressure, resolution, integration time),
and the spectral file name. A hard copy of these data must be
maintained until the test results are accepted.
8.9 Signal Transmittance. Monitor the signal
transmittance through the instrumental system. If signal
transmittance (relative to the background) drops below 95 percent
in any spectral region where the sample does not absorb infrared
energy, then a new background spectrum must be obtained.
8.10 Post-test CTS. After the sampling run completion,
record the CTS spectrum. Analysis of the spectral band area used
for quantification from pre- and post-test CTS spectra should agree
to within ±5 percent or corrective action must be taken.
8.11 Post-test QA. The sample spectra shall be inspected
immediately after the run to verify that the gas matrix composition
was close to the assumed gas matrix, (this is necessary to account
for the concentrations of the interferants for use in the
analytical analysis programs), and to confirm that the sampling and
instrumental parameters were appropriate for the conditions
encountered.
9.0 Quality Control
Use analyte spiking to verify the effectiveness of the sampling
system for the target compounds in the actual kiln gas matrix. QA
spiking shall be performed before and after each sample run. QA
spiking shall be performed after the pre- and post-test CTS direct
and system calibrations. The system biases calculated from the pre-
and post-test dynamic analyte spiking shall be within ±30 percent
for the spiked surrogate analytes for the measurements to be
considered valid. See sections 9.3.1 through 9.3.2 for the
requisite calculations. Measurement of the undiluted spike
(direct-to-cell measurement) involves sending dry, spike gas to the
FTIR cell, filling the cell to 1 atmosphere and obtaining the
spectrum of this sample. The direct-to-cell measurement should be
performed before each analyte spike so that the recovery of the
dynamically spiked analytes may be calculated. Analyte spiking is
only effective for assessing the integrity of the sampling system
when the concentration of HCl in the source does not vary
substantially. Any attempt to quantify an analyte recovery in a
variable concentration matrix will result in errors in the expected
concentration of the spiked sample. If the kiln gas target analyte
concentrations vary by more than ±5 percent (or 5 ppm, whichever is
greater) in the time required to acquire a sample spectrum, it may
be necessary to: (1) Use a dual sample probe approach, (2) use two
independent FTIR measurement systems, (3) use alternate QA/QC
procedures, or (4) postpone testing until stable emission
concentrations are achieved. (See section 9.2.3 of this method). It
is recommended that a laboratory evaluation be performed before
attempting to employ this method under actual field conditions. The
laboratory evaluation shall include (1) performance of all
applicable calculations in section 4 of the FTIR Protocol; (2)
simulated analyte spiking experiments in dry (ambient) and
humidified sample matrices using HCl; and (3) performance of bias
(recovery) calculations from analyte spiking experiments. It is not
necessary to perform a laboratory evaluation before every field
test. The purpose of the laboratory study is to demonstrate that
the actual instrument and sampling system configuration used in
field testing meets the requirements set forth in this method.
9.1 Spike Materials. Perform analyte spiking with an HCl
standard to demonstrate the integrity of the sampling system.
9.1.1 An HCl standard of approximately 50 ppm in a balance of
ultra pure nitrogen is recommended. The SF6 (tracer) concentration
shall be 2 to 5 ppm depending upon the measurement pathlength. The
spike ratio (spike flow/total flow) shall be no greater than 1:10,
and an ideal spike concentration should approximate the native
effluent concentration.
9.1.2 The ideal spike concentration may not be achieved because
the target concentration cannot be accurately predicted prior to
the field test, and limited calibration standards will be available
during testing. Therefore, practical constraints must be applied
that allow the tester to spike at an anticipated concentration. For
these tests, the analyte concentration contributed by the HCl
standard spike should be 1 to 5 ppm or should more closely
approximate the native concentration if it is greater.
9.2 Spike Procedure
9.2.1 A spiking/sampling apparatus is shown in Figure 2.
Introduce the spike/tracer gas mixture at a constant flow (±2
percent) rate at approximately 10 percent of the total sample flow.
(For example, introduce the surrogate spike at 1 L/min 20 cc/min,
into a total sample flow rate of 10 L/min). The spike must be
pre-heated before introduction into the sample matrix to prevent a
localized condensation of the gas stream at the spike introduction
point. A heated sample transport line(s) containing multiple
transport tubes within the heated bundle may be used to spike gas
up through the sampling system to the spike introduction point. Use
a calibrated flow device (e.g., mass flow meter/controller), to
monitor the spike flow as indicated by a calibrated flow meter or
controller, or alternately, the SF6 tracer ratio may be calculated
from the direct measurement and the diluted measurement. It is
often desirable to use the tracer approach in calculating the
spike/total flow ratio because of the difficulty in accurately
measuring hot/wet total flow. The tracer technique has been
successfully used in past validation efforts (Reference 1).
9.2.2 Perform a direct-to-cell measurement of the dry, undiluted
spike gas. Introduce the spike directly to the FTIR cell, bypassing
the sampling system. Fill cell to 1 atmosphere and collect the
spectrum of this sample. Ensure that the spike gas has equilibrated
to the temperature of the measurement cell before acquisition of
the spectra. Inspect the spectrum and verify that the gas is dry
and contains negligible CO2. Repeat the process to obtain a second
direct-to-cell measurement. Analysis of spectral band areas for HCl
from these duplicate measurements should agree to within ±5 percent
of the mean.
9.2.3 Analyte Spiking. Determine whether the kiln gas
contains native concentrations of HCl by examination of preliminary
spectra. Determine whether the concentration varies significantly
with time by observing a continuously up-dated spectrum of sample
gas in the flow-through sampling mode. If the concentration varies
by more than ±5 percent during the period of time required to
acquire a spectra, then an alternate approach should be used. One
alternate approach uses two sampling lines to convey sample to the
gas distribution manifold. One of the sample lines is used to
continuously extract unspiked kiln gas from the source. The other
sample line serves as the analyte spike line. One FTIR system can
be used in this arrangement. Spiked or unspiked sample gas may be
directed to the FTIR system from the gas distribution manifold,
with the need to purge only the components between the manifold and
the FTIR system. This approach minimizes the time required to
acquire an equilibrated sample of spiked or unspiked kiln gas. If
the source varies by more than ±5 percent (or 5 ppm, whichever is
greater) in the time it takes to switch from the unspiked sample
line to the spiked sample line, then analyte spiking may not be a
feasible means to determine the effectiveness of the sampling
system for the HCl in the sample matrix. A second alternative is to
use two completely independent FTIR measurement systems. One system
would measure unspiked samples while the other system would measure
the spiked samples. As a last option, (where no other alternatives
can be used) a humidified nitrogen stream may be generated in the
field which approximates the moisture content of the kiln gas.
Analyte spiking into this humidified stream can be employed to
assure that the sampling system is adequate for transporting the
HCl to the FTIR instrumentation.
9.2.3.1 Adjust the spike flow rate to approximately 10 percent
of the total flow by metering spike gas through a calibrated mass
flowmeter or controller. Allow spike flow to equilibrate within the
sampling system before analyzing the first spiked kiln gas samples.
A minimum of two consecutive spikes are required. Analysis of the
spectral band area used for quantification should agree to within
±5 percent or corrective action must be taken.
9.2.3.2 After QA spiking is completed, the sampling system
components shall be purged with nitrogen or dry air to eliminate
traces of the HCl compound from the sampling system components.
Acquire a sample spectra of the nitrogen purge to verify the
absence of the calibration mixture.
9.2.3.3 Analyte spiking procedures must be carefully executed to
ensure that meaningful measurements are achieved. The requirements
of sections 9.2.3.3.1 through 9.2.3.3.4 shall be met.
9.2.3.3.1 The spike must be in the vapor phase, dry, and heated
to (or above) the kiln gas temperature before it is introduced to
the kiln gas stream.
9.2.3.3.2 The spike flow rate must be constant and accurately
measured.
9.2.3.3.3 The total flow must also be measured continuously and
reliably or the dilution ratio must otherwise be verified before
and after a run by introducing a spike of a non-reactive, stable
compound (i.e., tracer).
9.2.3.3.4 The tracer must be inert to the sampling system
components, not contained in the effluent gas, and readily detected
by the analytical instrumentation. Sulfur hexafluoride (SF6) has
been used successfully (References 1 and 2) for this purpose.
9.3 Calculations
9.3.1 Recovery. Calculate the percent recovery of the
spiked analytes using equations 1 and 2.

Sm = Mean
concentration of the analyte spiked effluent samples (observed).

Ce =
Expected concentration of the spiked samples (theoretical). DF =
Dilution Factor (Total flow/Spike flow). Total flow = spike flow
plus effluent flow. Cs = cylinder concentration of spike gas. Su =
native concentration of analytes in unspiked samples. The spike
dilution factor may be confirmed by measuring the total flow and
the spike flow directly. Alternately, the spike dilution can be
verified by comparing the concentration of the tracer compound in
the spiked samples (diluted) to the tracer concentration in the
direct (undiluted) measurement of the spike gas. If SF6 is the
tracer gas, then

[SF6]spike = the
diluted SF6 concentration measured in a spiked sample. [SF6]direct
= the SF6 concentration measured directly.
9.3.2 Bias. The bias may be determined by the difference between
the observed spike value and the expected response (i.e., the
equivalent concentration of the spiked material plus the analyte
concentration adjusted for spike dilution). Bias is defined by
section 6.3.1 of EPA Method 301 of this appendix (Reference 8)
as,

Where: B
= Bias at spike level. Sm = Mean concentration of the analyte
spiked samples. Ce = Expected concentration of the analyte in
spiked samples. Acceptable recoveries for analyte spiking are ±30
percent. Application of correction factors to the data based upon
bias and recovery calculations is subject to the approval of the
Administrator. 10.0 Calibration and Standardization
10.1 Calibration transfer standards (CTS). The EPA
Traceability Protocol gases or NIST traceable standards, with a
minimum accuracy of ±2 percent shall be used. For other
requirements of the CTS, see the FTIR Protocol section 4.5.
10.2 Signal-to-Noise Ratio (S/N). The S/N shall be less
than the minimum acceptable measurement uncertainty in the
analytical regions to be used for measuring HCl.
10.3 Absorbance Pathlength. Verify the absorbance path
length by comparing CTS spectra to reference spectra of the
calibration gas(es).
10.4 Instrument Resolution. Measure the line width of
appropriate CTS band(s) to verify instrumental resolution.
10.5 Apodization Function. Choose the appropriate
apodization function. Determine any appropriate mathematical
transformations that are required to correct instrumental errors by
measuring the CTS. Any mathematical transformations must be
documented and reproducible. Reference 9 provides additional
information about FTIR instrumentation.
11.0 Analytical Procedure
A full description of the analytical procedures is given in
sections 4.6-4.11, sections 5, 6, and 7, and the appendices of the
FTIR Protocol. Additional description of quantitative spectral
analysis is provided in References 10 and 11.
12.0 Data Analysis and Calculations
Data analysis is performed using appropriate reference spectra
whose concentrations can be verified using CTS spectra. Various
analytical programs (References 10 and 11) are available to relate
sample absorbance to a concentration standard. Calculated
concentrations should be verified by analyzing spectral baselines
after mathematically subtracting scaled reference spectra from the
sample spectra. A full description of the data analysis and
calculations may be found in the FTIR Protocol (sections 4.0, 5.0,
6.0 and appendices).
12.1 Calculated concentrations in sample spectra are corrected
for differences in absorption pathlength between the reference and
sample spectra by

Where:
Ccorr = The pathlength corrected concentration. Ccalc = The initial
calculated concentration (output of the multicomponent analysis
program designed for the compound). Lr = The pathlength associated
with the reference spectra. Ls = The pathlength associated with the
sample spectra. Ts = The absolute temperature (K) of the sample
gas. Tr = The absolute temperature (K) at which reference spectra
were recorded.
12.2 The temperature correction in equation 5 is a volumetric
correction. It does not account for temperature dependence of
rotational-vibrational relative line intensities. Whenever
possible, the reference spectra used in the analysis should be
collected at a temperature near the temperature of the FTIR cell
used in the test to minimize the calculated error in the
measurement (FTIR Protocol, appendix D). Additionally, the
analytical region chosen for the analysis should be sufficiently
broad to minimize errors caused by small differences in relative
line intensities between reference spectra and the sample
spectra.
13.0 Method Performance
A description of the method performance may be found in the FTIR
Protocol. This method is self validating provided the results meet
the performance specification of the QA spike in sections 9.0
through 9.3 of this method.
14.0 Pollution Prevention
This is a gas phase measurement. Gas is extracted from the
source, analyzed by the instrumentation, and discharged through the
instrument vent.
15.0 Waste Management
Gas standards of HCl are handled according to the instructions
enclosed with the material safety data sheet.
16.0 References
1. “Laboratory and Field Evaluation of a Methodology for
Determination of Hydrogen Chloride Emissions From Municipal and
Hazardous Waste Incinerators,” S.C. Steinsberger and J.H. Margeson.
Prepared for U.S. Environmental Protection Agency, Research
Triangle Park, NC. NTIS Report No. PB89-220586. (1989).
2. “Evaluation of HCl Measurement Techniques at Municipal and
Hazardous Waste Incinerators,” S.A. Shanklin, S.C. Steinsberger,
and L. Cone, Entropy, Inc. Prepared for U.S. Environmental
Protection Agency, Research Triangle Park, NC. NTIS Report No.
PB90-221896. (1989).
3. “Fourier Transform Infrared (FTIR) Method Validation at a
Coal Fired-Boiler,” Entropy, Inc. Prepared for U.S. Environmental
Protection Agency, Research Triangle Park, NC. EPA Publication No.
EPA-454/R95-004. NTIS Report No. PB95-193199. (1993).
4. “Field Validation Test Using Fourier Transform Infrared
(FTIR) Spectrometry To Measure Formaldehyde, Phenol and Methanol at
a Wool Fiberglass Production Facility.” Draft. U.S. Environmental
Protection Agency Report, Entropy, Inc., EPA Contract No. 68D20163,
Work Assignment I-32.
5. Kinner, L.L., Geyer, T.G., Plummer, G.W., Dunder, T.A.,
Entropy, Inc. “Application of FTIR as a Continuous Emission
Monitoring System.” Presentation at 1994 International Incineration
Conference, Houston, TX. May 10, 1994.
6. “Molecular Vibrations; The Theory of Infrared and Raman
Vibrational Spectra,” E. Bright Wilson, J.C. Decius, and P.C.
Cross, Dover Publications, Inc., 1980. For a less intensive
treatment of molecular rotational-vibrational spectra see, for
example, “Physical Chemistry,” G.M. Barrow, chapters 12, 13, and
14, McGraw Hill, Inc., 1979.
7. “Laboratory and Field Evaluations of Ammonium Chloride
Interference in Method 26,” U.S. Environmental Protection Agency
Report, Entropy, Inc., EPA Contract No. 68D20163, Work Assignment
No. I-45.
8. 40 CFR 63, appendix A. Method 301 - Field Validation of
Pollutant Measurement Methods from Various Waste Media.
9. “Fourier Transform Infrared Spectrometry,” Peter R. Griffiths
and James de Haseth, Chemical Analysis, 83, 16-25, (1986), P.J.
Elving, J.D. Winefordner and I.M. Kolthoff (ed.), John Wiley and
Sons.
10. “Computer-Assisted Quantitative Infrared Spectroscopy,”
Gregory L. McClure (ed.), ASTM Special Publication 934 (ASTM),
1987.
11. “Multivariate Least-Squares Methods Applied to the
Quantitative Spectral Analysis of Multicomponent Mixtures,” Applied
Spectroscopy, 39(10), 73-84, 1985.

Method 323 -
Measurement of Formaldehyde Emissions From Natural Gas-Fired
Stationary Sources - Acetyl Acetone Derivatization Method
1.0 Introduction. This method describes the sampling and
analysis procedures of the acetyl acetone colorimetric method for
measuring formaldehyde emissions in the exhaust of natural
gas-fired, stationary combustion sources. This method, which was
prepared by the Gas Research Institute (GRI), is based on the
Chilled Impinger Train Method for Methanol, Acetone, Acetaldehyde,
Methyl Ethyl Ketone, and Formaldehyde (Technical Bulletin No. 684)
developed and published by the National Council of the Paper
Industry for Air and Stream Improvement, Inc. (NCASI). However,
this method has been prepared specifically for formaldehyde and
does not include specifications (e.g., equipment and
supplies) and procedures (e.g., sampling and analytical) for
methanol, acetone, acetaldehyde, and methyl ethyl ketone. To obtain
reliable results, persons using this method should have a thorough
knowledge of at least Methods 1 and 2 of 40 CFR part 60, appendix
A-1; Method 3 of 40 CFR part 60, appendix A-2; and Method 4 of 40
CFR part 60, appendix A-3.
1.1 Scope and Application
1.1.1 Analytes. The only analyte measured by this method is
formaldehyde (CAS Number 50-00-0).
1.1.2 Applicability. This method is for analyzing formaldehyde
emissions from uncontrolled and controlled natural gas-fired,
stationary combustion sources.
1.1.3 Data Quality Objectives. If you adhere to the quality
control and quality assurance requirements of this method, then you
and future users of your data will be able to assess the quality of
the data you obtain and estimate the uncertainty in the
measurements.
2.0 Summary of Method. An emission sample from the combustion
exhaust is drawn through a midget impinger train containing chilled
reagent water to absorb formaldehyde. The formaldehyde
concentration in the impinger is determined by reaction with acetyl
acetone to form a colored derivative which is measured
colorimetrically.
3.0 Definitions
[Reserved]
4.0 Interferences. The presence of acetaldehyde, amines,
polymers of formaldehyde, periodate, and sulfites can cause
interferences with the acetyl acetone procedure which is used to
determine the formaldehyde concentration. However, based on
experience gained from extensive testing of natural gas-fired
combustion sources using FTIR to measure a variety of compounds,
GRI expects only acetaldehyde to be potentially present when
combusting natural gas. Acetaldehyde has been reported to be a
significant interference only when present at concentrations above
50 ppmv. However, GRI reports that the concentration of
acetaldehyde from gas-fired sources is very low (typically below
the FTIR detection limit of around 0.5 ppmv); therefore, the
potential positive bias due to acetaldehyde interference is
expected to be negligible.
5.0 Safety
5.1 Prior to applying the method in the field, a site-specific
Health and Safety Plan should be prepared. General safety
precautions include the use of steel-toed boots, safety glasses,
hard hats, and work gloves. In certain cases, facility policy may
require the use of fire-resistant clothing while on-site. Since the
method involves testing at high-temperature sampling locations,
precautions must be taken to limit the potential for exposure to
high-temperature gases and surfaces while inserting or removing the
sample probe. In warm locations, precautions must also be taken to
avoid dehydration.
5.2 Potential chemical hazards associated with sampling include
formaldehyde, nitrogen oxides (NOX), and carbon monoxide (CO).
Formalin solution, used for field spiking, is an aqueous solution
containing formaldehyde and methanol. Formaldehyde is a skin, eye,
and respiratory irritant and a carcinogen, and should be handled
accordingly. Eye and skin contact and inhalation of formaldehyde
vapors should be avoided. Natural gas-fired combustion sources can
potentially emit CO at toxic concentrations. Care should be taken
to minimize exposure to the sample gas while inserting or removing
the sample probe. If the work area is enclosed, personal CO
monitors should be used to insure that the concentration of CO in
the work area is maintained at safe levels.
5.3 Potential chemical hazards associated with the analytical
procedures include acetyl acetone and glacial acetic acid. Acetyl
acetone is an irritant to the skin and respiratory system, as well
as being moderately toxic. Glacial acetic acid is highly corrosive
and is an irritant to the skin, eyes, and respiratory system. Eye
and skin contact and inhalation of vapors should be avoided. Acetyl
acetone and glacial acetic acid have flash points of 41 °C (105.8
°F) and 43 °C (109.4 °F), respectively. Exposure to heat or flame
should be avoided.
6.0 Equipment and Supplies
6.1 Sampling Probe. Quartz glass probe with stainless steel
sheath or stainless steel probe.
6.2 Teflon Tubing. Teflon tubing to connect the sample probe to
the impinger train. A heated sample line is not needed since the
sample transfer system is rinsed to recover condensed formaldehyde
and the rinsate combined with the impinger contents prior to sample
analysis.
6.3 Midget Impingers. Three midget impingers are required for
sample collection. The first impinger serves as a moisture
knockout, the second impinger contains 20 mL of reagent water, and
the third impinger contains silica gel to remove residual moisture
from the sample prior to the dry gas meter.
6.4 Vacuum Pump. Vacuum pump capable of delivering a controlled
extraction flow rate between 0.2 and 0.4 L/min.
6.5 Flow Measurement Device. A rotameter or other flow
measurement device is required to indicate consistent sample
flow.
6.6 Dry Gas Meter. A dry gas meter is used to measure the total
sample volume collected. The dry gas meter must be sufficiently
accurate to measure the sample volume to within 2 percent,
calibrated at the selected flow rate and conditions actually
encountered during sampling, and equipped with a temperature sensor
(dial thermometer, or equivalent) capable of measuring temperature
accurately to within 3 °C (5.4 °F).
6.7 Spectrophotometer. A spectrophotometer is required for
formaldehyde analysis, and must be capable of measuring absorbance
at 412 nm.
7.0 Reagents and Standards 7.1 Sampling Reagents
7.1.1 Reagent water. Deionized, distilled, organic-free water.
This water is used as the capture solution, for rinsing the sample
probe, sample line, and impingers at the completion of the sampling
run, in reagent dilutions, and in blanks.
7.1.2 Ice. Ice is necessary to pack around the impingers during
sampling in order to keep the impingers cold. Ice is also needed
for sample transport and storage.
7.2 Analysis
7.2.1 Acetyl acetone Reagent. Prepare the acetyl acetone reagent
by dissolving 15.4 g of ammonium acetate in 50 mL of reagent water
in a 100-mL volumetric flask. To this solution, add 0.20 mL of
acetyl acetone and 0.30 mL of glacial acetic acid. Mix the solution
thoroughly, then dilute to 100 mL with reagent water. The solution
can be stored in a brown glass bottle in the refrigerator, and is
stable for at least two weeks.
7.2.2 Formaldehyde. Reagent grade.
7.2.3 Ammonium Acetate
7.2.4 Glacial Acetic Acid
8.0 Sample Collection, Preservation, Storage, and Transport 8.1
Pre-test
8.1.1 Collect information about the site characteristics such as
exhaust pipe diameter, gas flow rates, port location, access to
ports, and safety requirements during a pre-test site survey. You
should then decide the sample collection period per run and the
target sample flow rate based on your best estimate of the
formaldehyde concentration likely to be present. You want to assure
that sufficient formaldehyde is captured in the impinger solution
so that it can be measured precisely by the spectrophotometer. You
may use Equation 323-1 to design your test program. As a guideline
for optimum performance, if you can, design your test so that the
liquid concentration (Cl) is approximately 10 times the assumed
spectrophotometer detection limit of 0.2 µg/mL. However, since
actual detection limits are instrument specific, we also suggest
that you confirm that the laboratory equipment can meet or exceed
this detection limit.
8.1.2 Prepare and then weigh the midget impingers prior to
configuring the sampling train. The first impinger is initially
dry. The second impinger contains 20 mL of reagent water, and the
third impinger contains silica gel that is added before weighing
the impinger. Each prepared impinger is weighed and the
pre-sampling weight is recorded to the nearest 0.5 gm.
8.1.3 Assemble the sampling train (see Figure 1). Ice is packed
around the impingers in order to keep them cold during sample
collection. A small amount of water may be added to the ice to
improve thermal transfer.
8.1.4 Perform a sampling system leak check (from the probe tip
to the pump outlet) as follows: Connect a rotameter to the outlet
of the pump. Close off the inlet to the probe and observe the leak
rate. The leak rate must be less than 2 percent of the planned
sampling rate of 0.2 or 0.4 L/min.
8.1.5 Source gas temperature and static pressure should also be
considered prior to field sampling to ensure adequate safety
precautions during sampling.
8.2 Sample Collection
8.2.1 Set the sample flow rate between 0.2-0.4 L/min, depending
upon the anticipated concentration of formaldehyde in the engine
exhaust. (You may have to refer to published data for anticipated
concentration levels - see References 5 and 6.) If no information
is available for the anticipated levels of formaldehyde, use the
higher sampling rate of 0.4 L/min.
8.2.2 Record the sampling flow rate every 5 to 10 minutes during
the sample collection period.
Note:
It is critical that you do not sample at a flow rate higher than
0.4 L/min. Sampling at higher flow rates may reduce formaldehyde
collection efficiency resulting in measured formaldehyde
concentrations that are less than the actual concentrations.
8.2.3 Monitor the amount of ice surrounding the impingers and
add ice as necessary to maintain the proper impinger temperature.
Remove excess water as needed to maintain an adequate amount of
ice.
8.2.4 Record measured leak rate, beginning and ending times and
dry gas meter readings for each sampling run, impinger weights
before and after sampling, and sampling flow rates and dry gas
meter exhaust temperature every 5 to 10 minutes during the run, in
a signed and dated notebook.
8.2.5 If possible, monitor and record the fuel flow rate to the
engine and the exhaust oxygen concentration during the sampling
period. This data can be used to estimate the engine exhaust flow
rate based on the Method 19 approach. This approach, if accurate
fuel flow rates can be determined, is preferred for reciprocating
IC engine exhaust flow rate estimation due to the pulsating nature
of the engine exhaust. The F-Factor procedures described in Method
19 may be used based on measurement of fuel flow rate and exhaust
oxygen concentration. One example equation is Equation 323-2.
8.3 Post-test. Perform a sampling system leak-check (from the
probe tip to pump outlet). Connect a rotameter to the outlet of the
pump. Close off the inlet to the probe and observe the leak rate.
The leak rate must be less than 2 percent of the sampling rate.
Weigh and record each impinger immediately after sampling to
determine the moisture weight gain. The impinger weights are
measured before transferring the impinger contents, and before
rinsing the sample probe and sample line. The moisture content of
the exhaust gas is determined by measuring the weight gain of the
impinger solutions and volume of gas sampled as described in Method
4. Rinse the sample probe and sample line with reagent water.
Transfer the impinger catch to an amber 40-mL VOA bottle with a
Teflon-lined cap. If there is a small amount of liquid in the
dropout impinger (<10 mL), the impinger catches can be combined
in one 40 mL VOA bottle. If there is a larger amount of liquid in
the dropout impinger, use a larger VOA bottle to combine the
impinger catches. Rinse the impingers and combine the rinsings from
the sample probe, sample line, and impingers with the impinger
catch. In general, combined rinse volumes should not exceed 10 mL.
However, in cases where a long, flexible extension line must be
used to connect the sample probe to the sample box, sufficient
water must be used to rinse the connecting line to insure that any
sample that may have collected there is recovered. The volume of
the rinses during sample recovery should not be excessive as this
may result in your having to use a larger VOA bottle. This in turn
would raise the detection limit of the method since after combining
the rinses with the impinger catches in the VOA bottle, the bottle
should be filled with reagent water to eliminate the headspace in
the sample vial. Keep the sample bottles over ice until analyzed
on-site or received at the laboratory. Samples should be analyzed
as soon as possible to minimize possible sample degradation. Based
on a limited number of previous analyses, samples held in
refrigerated conditions showed some sample degradation over
time.
8.4 Quality Control Samples
8.4.1 Field Duplicates. During at least one run, a pair of
samples should be collected concurrently and analyzed as separate
samples. Results of the field duplicate samples should be
identified and reported with the sample results. The percent
difference in exhaust (stack) concentration indicated by field
duplicates should be within 20 percent of their mean concentration.
Data are to be flagged as suspect if the duplicates do not meet the
acceptance criteria.
8.4.2 Spiked Samples. An aliquot of one sample from each source
sample set should be spiked at 2 to 3 times the formaldehyde level
found in the unspiked sample. It is also recommended that a second
aliquot of the same sample be spiked at around half the level of
the first spike; however, the second spike is not mandatory. The
results are acceptable if the measured spike recovery is 80 to 120
percent. Use Equation 323-4. Data are to be flagged as suspect if
the spike recovery do not meet the acceptance criteria.
8.4.3 Field Blank. A field blank consisting of reagent water
placed in a clean impinger train, taken to the test site but not
sampled, then recovered and analyzed in the same manner as the
other samples, should be collected with each set of source samples.
The field blank results should be less than 50 percent of the
lowest calibration standard used in the sample analysis. If this
criteria is not met, the data should be flagged as suspect.
9.0 Quality Control
QA/QC |
Acceptance |
Frequency |
Corrective action |
Leak-check -
Sections 8.1.4, 8.3 |
<2% of Sampling rate |
Pre- and Post-sampling |
Pre-sampling: Repair leak and
recheck
Post-sampling: Flag data and repeat run if for regulatory
compliance. |
Sample flow
rate |
Between 0.2 and 0.4 L/min |
Throughout sampling |
Adjust. |
VOA vial
headspace |
No headspace |
After sample recovery |
Flag data. |
Sample
preservation |
Maintain on ice |
After sample recovery |
Flag data. |
Sample hold
time |
14 day maximum |
After sample recovery |
Flag data. |
Field Duplicates -
Section 8.4.1 |
Within 20% of mean of original
and duplicate sample |
One duplicate per source
sample set |
Flag data. |
Spiked Sample -
Section 8.4.2 |
Recovery between 80 and
120% |
One spike per source sample
set |
Flag data. |
Field Blank -
Section 8.4.3 |
<50% of the lowest
calibration standard |
One blank per source sample
set |
Flag data. |
Calibration
Linearity - Section 10.1 |
Correlation coefficient of
0.99 or higher |
Per source sample set |
Repeat calibration
procedures. |
Calibration Check
Standard - Section 10.3 |
Within 10% of theoretical
value |
One calibration check per
source sample set |
Repeat check, remake standard
and repeat, repeat calibration. |
Lab Duplicates -
Section 11.2.1 |
Within 10% of mean of original
and duplicate sample analysis |
One duplicate per 10
samples |
Flag data. |
Analytical Blanks
- Section 11.2.2 |
<50% of the lowest
calibration standard |
One blank per source sample
set |
Clean glassware/analytical
equipment and repeat. |
10.0 Calibration and Standardization
10.1 Spectrophotometer Calibration. Prepare a stock solution of
10 µg/mL formaldehyde. Prepare a series of calibration standards
from the stock solution by adding 0, 0.1, 0.3, 0.7, 1.0, and 1.5 mL
of stock solution (corresponding to 0, 1.0, 3.0, 7.0, 10.0, and
15.0 µg formaldehyde, respectively) to screw-capped vials. Adjust
each vial's volume to 2.0 mL with reagent water. At this point the
concentration of formaldehyde in the standards is 0.0, 0.5, 1.5,
3.5, 5.0, and 7.5 µg/mL, respectively. Add 2.0 mL of acetyl acetone
reagent, thoroughly mix the solution, and place the vials in a
water bath (or heating block) at 60 °C for 10 minutes. Remove the
vials and allow to cool to room temperature. Transfer each solution
to a cuvette and measure the absorbance at 412 nm using the
spectrophotometer. Develop a calibration curve from the analytical
results of these standards. The acceptance criteria for the
spectrophotometer calibration is a correlation coefficient of 0.99
or higher. If this criteria is not met, the calibration procedures
should be repeated.
10.2 Spectrophotometer Zero. The spectrophotometer should be
zeroed with reagent water when analyzing each set of samples.
10.3 Calibration Checks. Calibration checks consisting of
analyzing a standard separate from the calibration standards must
be performed with each set of samples. The calibration check
standard should not be prepared from the calibration stock
solution. The result of the check standard must be within 10
percent of the theoretical value to be acceptable. If the
acceptance criteria are not met, the standard must be reanalyzed.
If still unacceptable, a new calibration curve must be prepared
using freshly prepared standards.
11.0 Analytical Procedure
11.1 Sample Analysis. A 2.0-mL aliquot of the impinger
catch/rinsate is transferred to a screw-capped vial. Two mL of the
acetyl acetone reagent are added and the solution is thoroughly
mixed. Once mixed, the vial is placed in a water bath (or heating
block) at 60 °C for 10 minutes. Remove the vial and allow to cool
to room temperature. Transfer the solution to a cuvette and measure
the absorbance using the spectrophotometer at 412 nm. The quantity
of formaldehyde present is determined by comparing the sample
response to the calibration curve. Use Equation 323-5. If the
sample response is out of the calibration range, the sample must be
diluted and reanalyzed. Such dilutions must be performed on another
aliquot of the original sample before the addition of the acetyl
acetone reagent. The full procedure is repeated with the diluted
sample.
11.2 Analytical Quality Control
11.2.1 Laboratory Duplicates. Two aliquots of one sample from
each source sample set should be prepared and analyzed (with a
minimum of one pair of aliquots for every 10 samples). The percent
difference between aliquot analysis should be within 10 percent of
their mean. Use Equation 323-3. Data are flagged if the laboratory
duplicates do not meet this criteria.
11.2.2 Analytical blanks. Blank samples (reagent water) should
be incorporated into each sample set to evaluate the possible
presence of any cross-contamination. The acceptance criteria for
the analytical blank is less than 50 percent of the lowest
calibration standard. If the analytical blank does not meet this
criteria, the glassware/analytical equipment should be cleaned and
the analytical blank repeated.
12.0 Calculations and Data Analysis
12.1 Nomenclature
A = measured absorbance of 2 mL aliquot B = estimated sampling
rate, Lpm Cl = target concentration in liquid, µg/mL D = estimated
stack formaldehyde concentration (ppmv) E = estimated liquid
volume, normally 40 mL (the size of the VOA used) cform =
formaldehyde concentration in gas stream, ppmvd cform @15%02 =
formaldehyde concentration in gas stream corrected to 15% oxygen,
ppmvd Csm = measured concentration of formaldehyde in the spiked
aliquot Cu = measured concentration of formaldehyde in the unspiked
aliquot of the same sample Cs = calculated concentration of
formaldehyde spiking solution added to the spiked aliquot F =
dilution factor, 1 unless dilution of the sample was needed to
reduce the absorbance into the calibration range Fd = dry basis
F-factor from Method 19, dscf per million btu GCVg = Gross
calorific value (or higher heating value), btu per scf Kc =
spectrophotometer calibration factor, slope of the least square
regression line, µg/absorbance (Note: Most spreadsheets are capable
of calculating a least squares line.) K1 = 0.3855°K/mm Hg for
metric units, (17.65°R/in.Hg for English units.) MW = molecular
weight, 30 g/g-mole, for formaldehyde 24.05 = mole specific volume
constant, liters per g-mole m = mass of formaldehyde in liquid
sample, mg Pstd = Standard pressure, 760 mm Hg (29.92 in.Hg) Pbar =
Barometric pressure, mm Hg (in.Hg) PD = Percent Difference Qe =
exhaust flow rate, dscf per minute Qg = natural gas fuel flow rate,
scf per minute Tm = Average DGM absolute temperature, °K (°R). Tstd
= Standard absolute temperature, 293 °K (528 °R). t = sample time
(minutes) Vm = Dry gas volume as measured by the DGM, dcm (dcf).
Vm(std) = Dry gas volume measured by the DGM, corrected to standard
conditions of 1 atmosphere and 20 °C, dscm (dscf). Vt = actual
total volume of impinger catch/rinsate, mL Va = volume (2.0) of
aliquot analyzed, mL X1 = first value X2 = second value O2d =
oxygen concentration measured, percent by volume, dry basis %R =
percent recovery of spike Zu = volume fraction of unspiked (native)
sample contained in the final spiked aliquot [
e.g., Vu/(Vu +
Vs), where Vu + Vs should = 2.0 mL] Zs = volume fraction of spike
solution contained in the final spiked aliquot [
e.g., Vs/(Vu
+ Vs)] R = 0.02405 dscm per g-mole, for metric units at standard
conditions of 1 atmosphere and 20 °C Y = Dry Gas Meter calibration
factor
12.2 Pretest Design
12.3 Exhaust Flow Rate
12.4 Percent Difference - (Applicable to Field and Lab
Duplicates)
12.5 Percent Recovery of Spike
12.6 Mass of Formaldehyde in Liquid Sample
12.7 Dry Gas Sample Volume Corrected to Standard Conditions
12.8 Formaldehyde Concentration in gas Stream
12.9 Formaldehyde Concentration Corrected to 15% Oxygen

13.0
Method Performance
13.1 Precision. Based on a Method 301 validation using quad
train arrangement with post sampling spiking study of the method at
a natural gas-fired IC engine, the relative standard deviation of
six pairs of unspiked samples was 11.2 percent at a mean stack gas
concentration of 16.7 ppmvd.
13.2 Bias. No bias correction is allowed. The single Method 301
validation study of the method at a natural gas-fired IC engine,
indicated a bias correction factor of 0.91 for that set of data. An
earlier spiking study got similar average percent spike recovery
when spiking into a blank sample. This data set is too limited to
justify using a bias correction factor for future tests at other
sources.
13.3 Range. The range of this method for formaldehyde is 0.2 to
7.5 µg/mL in the liquid phase. (This corresponds to a range of 0.27
to 10 ppmv in the engine exhaust if sampling at a rate of 0.4 Lpm
for 60 minutes and using a 40-mL VOA bottle.) If the liquid sample
concentration is above this range, perform the appropriate dilution
for accurate measurement. Any dilutions must be taken from new
aliquots of the original sample before reanalysis.
13.4 Sample Stability. Based on a sample stability study
conducted in conjunction with the method validation, sample
degradation for 7- and 14-day hold times does not exceed 2.3 and
4.6 percent, respectively, based on a 95 percent level of
confidence. Therefore, the recommended maximum sample holding time
for the underivatized impinger catch/rinsings is 14 days, where
projected sample degradation is below 5 percent.
14.0 Pollution Prevention
Sample gas from the combustion source exhaust is vented to the
atmosphere after passing through the chilled impinger sampling
train. Reagent solutions and samples should be collected for
disposal as aqueous waste.
15.0 Waste Management
Standards of formaldehyde and the analytical reagents should be
handled according to the Material Safety Data Sheets.
16.0 References
1. National Council of the Paper Industry for Air and Stream
Improvement, Inc. “Volatile Organic Emissions from Pulp and Paper
Mill Sources, Part X - Test Methods, Quality Assurance/Quality
Control Procedures, and Data Analysis Protocols.” Technical
Bulletin No. 684, December 1994.
2. National Council of the Paper Industry for Air and Stream
Improvement, Inc., “Field Validation of a Source Sampling Method
for Formaldehyde, Methanol, and Phenol at Wood Products Mills.”
1997 TAPPI International Environmental Conference.
3. Roy F. Weston, Inc. “Formaldehyde Sampling Method Field
Evaluation and Emission Test Report for Georgia-Pacific Resins,
Inc., Russellville, South Carolina.” August 1996.
4. Hoechst Celanese Method CL 8-4. “Standard Test Method for
Free Formaldehyde in Air Using Acetyl Acetone.” Revision 0,
September 1986.
5. Shareef, G.S., et al. “Measurement of Air Toxic
Emissions from Natural Gas-Fired Internal Combustion Engines at
Natural Gas Transmission and Storage Facilities.” Report No.
GRI-96/0009.1, Gas Research Institute, Chicago, Illinois, February
1996.
6. Gundappa, M., et al. “Characteristics of Formaldehyde
Emissions from Natural Gas-Fired Reciprocating Internal Combustion
Engines in Gas Transmission. Volume I: Phase I Predictive Model for
Estimating Formaldehyde Emissions from 2-Stroke Engines.” Report
No. GRI-97/0376.1, Gas Research Institute, Chicago, Illinois,
September 1997.
17.0 Tables, Diagrams, Flowcharts, and Validation Data

Method 325A -
Volatile Organic Compounds from Fugitive and Area Sources: Sampler
Deployment and VOC Sample Collection 1.0 Scope and Application
1.1 This method describes collection of volatile organic
compounds (VOCs) at or inside a facility property boundary or from
fugitive and area emission sources using passive (diffusive) tube
samplers (PS). The concentration of airborne VOCs at or near these
potential fugitive- or area-emission sources may be determined
using this method in combination with Method 325B. Companion Method
325B (Sampler Preparation and Analysis) describes preparation of
sampling tubes, shipment and storage of exposed sampling tubes, and
analysis of sampling tubes collected using either this passive
sampling procedure or alternative active (pumped) sampling
methods.
1.2 This method may be used to determine the average
concentration of the select VOCs using the corresponding uptake
rates listed in Method 325B, Table 12.1. Additional compounds or
alternative sorbents must be evaluated as described in Addendum A
of Method 325B or by one of the following national/international
standard methods: ISO 16017-2:2003(E), ASTM D6196-03 (Reapproved
2009), or BS EN 14662-4:2005 (all incorporated by reference - see §
63.14), or reported in the peer-reviewed open literature.
1.3 Methods 325A and 325B are valid for the measurement of
benzene. Supporting literature (References 1-8) indicates that
benzene can be measured by flame ionization detection or mass
spectrometry over a concentration range of approximately 0.5
micrograms per cubic meter (µg/m 3) to at least 500 µg/m 3 when
industry standard (3.5 inch long × 0.25 inch outside diameter
(o.d.) × 5 mm inner diameter (i.d.)) inert-coated stainless steel
sorbent tubes packed with Carbograph TM 1 TD, Carbopack TM B, or
Carbopack TM X or equivalent are used and when samples are
accumulated over a period of 14 days.
1.4 This method may be applied to screening average airborne VOC
concentrations at facility property boundaries or monitoring
perimeters over an extended period of time using multiple sampling
periods (e.g., 26 × 14-day sampling periods). The duration
of each sampling period is normally 14 days.
1.5 This method requires the collection of local meteorological
data (wind speed and direction, temperature, and barometric
pressure). Although local meteorology is a component of this
method, non-regulatory applications of this method may use regional
meteorological data. Such applications risk that the results may
not identify the precise source of the emissions.
2.0 Summary of the Method 2.1 Principle of the Method
The diffusive passive sampler collects VOC from air for a
measured time period at a rate that is proportional to the
concentration of vapor in the air at that location.
2.1.1 This method describes the deployment of prepared passive
samplers, including determination of the number of passive samplers
needed for each survey and placement of samplers along or inside
the facility property boundary depending on the size and shape of
the site or linear length of the boundary.
2.1.2 The rate of sampling is specific to each compound and
depends on the diffusion constants of that VOC and the sampler
dimensions/characteristics as determined by prior calibration in a
standard atmosphere (Reference 1).
2.1.3 The gaseous VOC target compounds migrate through a
constant diffusion barrier (e.g., an air gap of fixed
dimensions) at the sampling end of the diffusion sampling tube and
adsorb onto the sorbent.
2.1.4 Heat and a flow of inert carrier gas are then used to
extract (desorb) the retained VOCs back from the sampling end of
the tube and transport/transfer them to a gas chromatograph (GC)
equipped with a chromatographic column to separate the VOCs and a
detector to determine the quantity of target VOCs.
2.1.5 Gaseous or liquid calibration standards loaded onto the
sampling ends of clean sorbent tubes must be used to calibrate the
analytical equipment.
2.1.6 This method requires the use of field blanks to ensure
sample integrity associated with shipment, collection, and storage
of the passive samples. It also requires the use of field
duplicates to validate the sampling process.
2.1.7 At the end of each sampling period, the passive samples
are collected, sealed, and shipped to a laboratory for analysis of
target VOCs by thermal desorption gas chromatography, as described
in Method 325B.
2.2 Application of Diffusive Sampling
2.2.1 This method requires deployment of passive sampling tubes
on a monitoring perimeter encompassing all known emission sources
at a facility and collection of local meteorological data. It may
be used to determine average concentration of VOC at a facility's
“fenceline” using time integrated passive sampling (Reference
2).
2.2.2 Collecting samples and meteorological data at
progressively higher frequencies may be employed to resolve shorter
term concentration fluctuations and wind conditions that could
introduce interfering emissions from other sources.
2.2.3 This passive sampling method provides a low cost approach
to screening of fugitive or area emissions compared to active
sampling methods that are based on pumped sorbent tubes or time
weighted average canister sampling.
2.2.3.1 Additional passive sampling tubes may be deployed at
different distances from the facility property boundary or from the
geometric center of the fugitive emission source.
2.2.3.2 Additional meteorological measurements may also be
collected as needed to perform preliminary gradient-based
assessment of the extent of the pollution plume at ground level and
the effect of “background” sources contributing to airborne VOC
concentrations at the location.
2.2.4 Time-resolved concentration measurements coupled with
time-resolved meteorological monitoring may be used to generate
data needed for source apportionment procedures and mass flux
calculations.
3.0 Definitions
(See also Section 3.0 of Method 325B.)
3.1 Fenceline means the property boundary of a facility
or internal monitoring perimeter established in accordance with the
requirements in Section 8.2 of this method.
3.2 Passive sampler (PS) means a specific type of sorbent
tube (defined in this method) that has a fixed dimension air
(diffusion) gap at the sampling end and is sealed at the other
end.
3.3 Passive sampling refers to the activity of
quantitatively collecting VOC on sorbent tubes using the process of
diffusion.
3.4 PSi is the annual average for all PS concentration
results from location i.
3.5 PSi3 is the set of annual average concentration
results for PSi and two sorbent tubes nearest to the PS location
i.
3.6 PSip is the concentration from the sorbent tube at
location i for the test period or episode p.
3.7 Sampling period is the length of time each passive
sampler is exposed during field monitoring. The sampling period for
this method is 14 days.
3.8 Sorbent tube (Also referred to as tube, PS tube,
adsorbent tube, and sampling tube) is an inert coated stainless
steel tube. Standard PS tube dimensions for this method are
3.5-inch (89 mm) long × 0.25-inch (6.4 mm) o.d. with an i.d. of 5
mm, a cross-sectional area of 19.6 mm 2 and an air gap of 15 mm.
The central portion of the tube is packed with solid adsorbent
material contained between 2 × 100-mesh stainless steel gauzes and
terminated with a diffusion cap at the sampling end of the tube.
These axial passive samplers are installed under a protective hood
during field deployment.
Note:
Glass and glass- (or fused silica-) lined stainless steel
sorbent tubes (typically 4 mm i.d.) are also available in various
lengths to suit different makes of thermal desorption equipment,
but these are rarely used for passive sampling because it is more
difficult to adequately define the diffusive air gap in glass or
glass-line tubing. Such tubes are not recommended for this
method.
4.0 Sampling Interferences 4.1 General Interferences
Passive tube samplers should be sited at a distance beyond the
influence of possible obstructions such as trees, walls, or
buildings at the monitoring site. Complex topography and physical
site obstructions, such as bodies of water, hills, buildings, and
other structures that may prevent access to a planned PS location
must be taken into consideration. You must document and report
siting interference with the results of this method.
4.2 Background Interference
Nearby or upwind sources of target emissions outside the
facility being tested can contribute to background concentrations.
Moreover, because passive samplers measure continuously, changes in
wind direction can cause variation in the level of background
concentrations from interfering sources during the monitoring
period. This is why local meteorological information, particularly
wind direction and speed, is required to be collected throughout
the monitoring period. Interfering sources can include neighboring
industrial facilities, transportation facilities, fueling
operations, combustion sources, short-term transient sources,
residential sources, and nearby highways or roads. As PS data are
evaluated, the location of potential interferences with respect to
PS locations and local wind conditions should be considered,
especially when high PS concentration values are observed.
4.3 Tube Handling
You must protect the PS tubes from gross external contamination
during field sampling. Analytical thermal desorption equipment used
to analyze PS tubes must desorb organic compounds from the interior
of PS tubes and exclude contamination from external sampler
surfaces in the analytical/sample flow path. If the analytical
equipment does not comply with this requirement, you must wear
clean, white, cotton or powder-free nitrile gloves to handle
sampling tubes to prevent contamination of the external sampler
surfaces. Sampling tubes must be capped with two-piece, brass, 0.25
inch, long-term storage caps fitted with combined
polytetrafluoroethylene ferrules (see Section 6.1 and Method 325B)
to prevent ingress of airborne contaminants outside the sampling
period. When not being used for field monitoring, the capped tubes
must be stored in a clean, air-tight, shipping container to prevent
the collection of VOCs (see Section 6.4.2 of Method 325B).
4.4 Local Weather Conditions and Airborne Particulates
Although air speeds are a constraint for many forms of passive
samplers, axial tube PS devices have such a slow inherent uptake
rate that they are largely immune to these effects (References
4,5). Passive samplers must nevertheless be deployed under
non-emitting weatherproof hoods to moderate the effect of local
weather conditions such as solar heating and rain. The cover must
not impede the ingress of ambient air. Sampling tubes should also
be orientated vertically and pointing downwards, to minimize
accumulation of particulates.
4.5 Temperature
The normal working range for field sampling for sorbent packing
is 0-40 °C (References 6,7). Note that most published passive
uptake rate data for sorbent tubes is quoted at 20 °C. Note also
that, as a rough guide, an increase in temperature of 10 °C will
reduce the collection capacity for a given analyte on a given
sorbent packing by a factor of 2, but the uptake rate will not
change significantly (Reference 4).
5.0 Safety
This method does not purport to include all safety issues or
procedures needed when deploying or collecting passive sampling
tubes. Precautions typical of field air sampling projects are
required. Tripping, falling, electrical, and weather safety
considerations must all be included in plans to deploy and collect
passive sampling tubes.
6.0 Sampling Equipment and Supplies, and Pre-Deployment Planning
This section describes the equipment and supplies needed to
deploy passive sampling monitoring equipment at a facility property
boundary. Details of the passive sampling tubes themselves and
equipment required for subsequent analysis are described in Method
325B.
6.1 Passive Sampling Tubes
The industry standard PS tubes used in this method must meet the
specific configuration and preparation requirements described in
Section 3.0 of this method and Section 6.1 of Method 325B.
Note:
The use of PS tubes packed with various sorbent materials for
monitoring a wide variety of organic compounds in ambient air has
been documented in the literature (References 4-10). Other sorbents
may be used in standard passive sampling tubes for monitoring
additional target compound(s) once their uptake rate and
performance has been demonstrated following procedures in Addendum
A to Method 325B. Guidance on sorbent selection can also be
obtained from relevant national and international standard methods
such as ASTM D6196-03 (Reapproved 2009) (Reference 14) and ISO
16017-2:2003(E) (Reference 13) (both incorporated by reference -
see § 63.14).
6.2 Passive or Diffusive Sampling Cap
One diffusive sampling cap is required per PS tube. The cap fits
onto the sampling end of the tube during air monitoring. The other
end of the tube remains sealed with the long-term storage cap. Each
diffusive sampling cap is fitted with a stainless steel gauze,
which defines the outer limit of the diffusion air gap.
6.3 Sorbent Tube Protection Cover
A simple weatherproof hood, suitable for protecting passive
sampling tubes from the worst of the weather (see Section 4.4)
consists of an inverted cone/funnel constructed of an inert,
non-outgassing material that fits over the diffusive tube, with the
open (sampling) end of the tube projecting just below the cone
opening. An example is shown in Figure 6.1 (Adapted from Reference
13).

6.4
Thermal Desorption Apparatus
If the analytical thermal desorber that will subsequently be
used to analyze the passive sampling tubes does not meet the
requirement to exclude outer surface contaminants from the sample
flow path (see Section 6.6 of Method 325B), then clean, white,
cotton or powder-free nitrile gloves must be used for handling the
passive sampling tubes during field deployment.
6.5 Sorbent Selection
Sorbent tube configurations, sorbents or other VOC not listed in
this method must be evaluated according to Method 325B, Addendum A
or ISO 16017-2:2003(E) (Reference 13) (incorporated by reference -
see § 63.14). The supporting evaluation and verification data
described in Method 325B, Addendum A for configurations or
compounds different from the ones described in this method must
meet the performance requirements of Method 325A/B and must be
submitted with the test plan for your measurement program.
7.0 Reagents and Standards
No reagents or standards are needed for the field deployment and
collection of passive sampling tubes. Specifications for sorbents,
gas and liquid phase standards, preloaded standard tubes, and
carrier gases are covered in Section 7 of Method 325B.
8.0 Sample Deployment, Recovery, and Storage
Pre-deployment and planning steps are required before field
deployment of passive sampling tubes. These activities include but
are not limited to conducting a site visit, determining suitable
and required monitoring locations, and determining the monitoring
frequency to be used.
8.1 Conducting the Site Visit
8.1.1 Determine the size and shape of the facility footprint in
order to determine the required number of monitoring locations.
8.1.2 Identify obstacles or obstructions (buildings, roads,
fences), hills and other terrain issues (e.g., bodies of
water or swamp land) that could interfere with air parcel flow to
the sampler or that prevent reasonable access to the location. You
may use the general guidance in Section 4.1 of this method during
the site visit to identify sampling locations. You must evaluate
the placement of each passive sampler to determine if the
conditions in this section are met.
8.1.3 Identify to the extent possible and record potential
off-site source interferences (e.g., neighboring industrial
facilities, transportation facilities, fueling operations,
combustion sources, short-term transient sources, residential
sources, nearby highways).
8.1.4 Identify the closest available meteorological station.
Identify potential locations for one or more on-site or near-site
meteorological station(s) following the guidance in
EPA-454/B-08-002 (Reference 11) (incorporated by reference - see §
63.14).
8.2 Determining Sampling Locations (References 2, 3)
8.2.1 The number and placement of the passive samplers depends
on the size, the shape of the facility footprint or the linear
distance around the facility, and the proximity of emission sources
near the property boundaries. Aerial photographs or site maps may
be used to determine the size (acreage) and shape of the facility
or the length of the monitoring perimeter. Place passive samplers
on an internal monitoring perimeter on or inside the facility
boundary encompassing all emission sources at the facility at
different angles circling the geometric center of the facility or
at different distances based on the monitoring perimeter length of
the facility.
Note:
In some instances, permanent air monitoring stations may already
be located in close proximity to the facility. These stations may
be operated and maintained by the site, or local or state
regulatory agencies. If access to the station is possible, a PS may
be deployed adjacent to other air monitoring instrumentation. A
comparison of the pollutant concentrations measured with the PS to
concentrations measured by site instrumentation may be used as an
optional data quality indicator to assess the accuracy of PS
results.
8.2.1.1 The monitoring perimeter may be located between the
property boundary and any potential emission source near the
property boundary, as long as the distance from the source to the
monitoring perimeter is at least 50 meters (162 feet). If a
potential emissions source is within 50 meters (162 feet) of the
property boundary, the property boundary shall be used as the
monitoring perimeter near that source.
8.2.1.2 Samplers need only be placed around the monitoring
perimeter and not along internal roads or other right of ways that
may bisect the facility.
8.2.1.3 An extra sampler must be placed near known sources of
VOCs if potential emission sources are within 50 meters (162 feet)
of the boundary and the source or sources are located between two
monitors. Measure the distance (x) between the two monitors and
place another monitor approximately halfway between (x/2 ±10
percent) the two monitors. Only one extra sampler is required
between two monitors to account for known sources of VOCs. For
example, in Figure 8.1, the facility added three additional
monitors (i.e., light shaded sampler locations), and in
Figure 8.2, the facility added two additional monitors to provide
sufficient coverage of all area sources.
Figure 8.1. Facility with a Regular Shape Between 750 and 1,500
Acres in Area

Figure 8.1.
Facility with a Regular Shape Between 750 and 1,500 Acres in Area
8.2.2 Option 1 for Determining Sampling Locations.
8.2.2.1 For facilities with a regular (circular, triangular,
rectangular, or square) shape, determine the geographic center of
the facility.
8.2.2.1.1 For facilities with an area of less than or equal to
750 acres, measure angles of 30 degrees from the center point for a
total of twelve 30 degree measurements evenly spaced (±1
degree).
8.2.2.1.2 For facilities covering an area greater than 750 acres
but less than or equal to 1,500 acres, measure angles of 20 degrees
from the center point for a total of eighteen 20 degree
measurements evenly spaced (±1 degree). Figure 8.1 shows the
monitor placement around the property boundary of a facility with
an area between 750 and 1,500 acres. Monitor placements are
represented with black dots along the property boundary.
8.2.2.1.3 For facilities covering an area greater than 1,500
acres, measure angles of 15 degrees from the center point for a
total of twenty-four 15 degree measurements evenly spaced (±1
degree).
8.2.2.1.4 Locate each sampling point where the measured angle
intersects the outer monitoring perimeter.
8.2.2.2 For irregularly shaped facilities, divide the area into
a set of connecting subarea circles, triangles or rectangles to
determine sampling locations. The subareas must be defined such
that a circle can reasonably encompass the subarea. Then determine
the geometric center point of each of the subareas.
8.2.2.2.1 If a subarea is less than or equal to 750 acres
(e.g., Figure 8.3), measure angles of 30 degrees from the
center point for a total of twelve 30 degree measurements (±1
degree).
8.2.2.2.2 If a subarea is greater than 750 acres but less than
or equal to 1,500 acres (e.g., Figure 8.4), measure angles
of 20 degrees from the center point for a total of eighteen 20
degree measurements (±1 degree).
8.2.2.2.3 If a subarea is greater than 1,500 acres, measure
angles of 15 degrees from the center for a total of twenty-four 15
degree measurements (±1 degree).
8.2.2.2.4 Locate each sampling point where the measured angle
intersects the outer monitoring perimeter. Sampling points need not
be placed closer than 152 meters (500 feet) apart (or 76 meters
(250 feet) if known sources are within 50 meters (162 feet) of the
monitoring perimeter), as long as a minimum of 3 monitoring
locations are used for each subarea.
8.2.2.2.5 Sampling sites are not needed at the intersection of
an inner boundary with an adjacent subarea. The sampling location
must be sited where the measured angle intersects the subarea's
outer monitoring perimeter.
8.2.3 Option 2 for Determining Sampling Locations.
8.2.3.1 For facilities with a monitoring perimeter length of
less than 7,315 meters (24,000 feet), a minimum of twelve sampling
locations evenly spaced ±10 percent of the location interval is
required.
8.2.3.2 For facilities with a monitoring perimeter length
greater than or equal to 7,315 meters (24,000 feet), sampling
locations are spaced 610 ± 76 meters (2,000 ± 250 feet) apart.
8.2.3.3 Unless otherwise specified in an applicable regulation,
permit or other requirement, for small disconnected subareas with
known sources within 50 meters (162 feet) of the monitoring
perimeter, sampling points need not be placed closer than 152
meters (500 feet) apart as long as a minimum of 3 monitoring
locations are used for each subarea.
8.3 Siting a Meteorological Station
A meteorological station is required at or near the facility you
are monitoring. A number of commercially available meteorological
stations can be used. Information on meteorological instruments can
be found in EPA-454/R-99-005 (Reference 11) (incorporated by
reference - see § 63.14). Some important considerations for siting
of meteorological stations are detailed below.
8.3.1 Place meteorological stations in locations that represent
conditions affecting the transport and dispersion of pollutants in
the area of interest. Complex terrain may require the use of more
than one meteorological station.
8.3.2 Deploy wind instruments over level, open terrain at a
height of 10 meters (33 feet). If possible, locate wind instruments
at a distance away from nearby structures that is equal to at least
10 times the height of the structure.
8.3.3 Protect meteorological instruments from thermal radiation
and adequately ventilate them using aspirated shields. The
temperature sensor must be located at a distance away from any
nearby structures that is equal to at least four times the height
of the structure. Temperature sensors must be located at least 30
meters (98 feet) from large paved areas.
8.3.4 Collect and record meteorological data, including wind
speed, wind direction, temperature and barometric pressure on an
hourly basis. Calculate average unit vector wind direction, sigma
theta, temperature and barometric pressure per sampling period to
enable calculation of concentrations at standard conditions. Supply
this information to the laboratory.
8.3.5 Identify and record the location of the meteorological
station by its GPS coordinate.
8.4 Monitoring Frequency
8.4.1 Sample collection may be performed for periods up to 14
days.
8.4.2 A site screening protocol that meets method requirements
may be performed by collecting samples for a year where each PS
accumulates VOC for a 14-day sampling period. Study results are
accumulated for the sampling periods (typically 26) over the course
of one calendar year. To the extent practical, sampling tubes
should be changed at approximately the same time of day at each of
the monitoring sites.
8.4.3 When extenuating circumstances do not permit safe
deployment or retrieval of passive samplers (e.g., extreme
weather, power failure), sampler placement or retrieval earlier or
later than the prescribed schedule is allowed but must occur as
soon as safe access to sampling sites is possible.
8.5 Passive Sampler Deployment
8.5.1 Clean (conditioned) sorbent tubes must be prepared and
packaged by the laboratory as described in Method 325B and must be
deployed for sampling within 30 days of conditioning.
8.5.2 Allow the tubes to equilibrate with ambient temperature
(approximately 30 minutes to 1 hour) at the monitoring location
before removing them from their storage/shipping container for
sample collection.
8.5.3 If there is any risk that the analytical equipment will
not meet the requirement to exclude contamination on outer tube
surfaces from the sample flow path (see Section 6.6 of Method
325B), sample handlers must wear clean, white, cotton or
powder-free nitrile gloves during PS deployment and collection and
throughout any other tube handling operations.
8.5.4 Inspect the sampling tubes immediately prior to
deployment. Ensure that they are intact, securely capped, and in
good condition. Any suspect tubes (e.g., tubes that appear
to have leaked sorbent) should be removed from the sampling
set.
8.5.5 Secure passive samplers so the bottom of the diffusive
sampling cap is 1.5 to 3 meters (4.9 to 9.8 feet) above ground
using a pole or other secure structure at each sampling location.
Orient the PS vertically and with the sampling end pointing
downward to avoid ingress of particulates.
Note:
Duplicate sampling assemblies must be deployed in at least one
monitoring location for every 10 monitoring locations during each
field monitoring period.
8.5.6 Protect the PS from rain and excessive wind velocity by
placing them under the type of protective hood described in Section
6.1.3 or equivalent.
8.5.7 Remove the storage cap on the sampling end of the tube and
replace it with a diffusive sampling cap at the start of the
sampling period. Make sure the diffusion cap is properly seated and
store the removed storage caps in the empty tube shipping
container.
8.5.8 Record the start time and location details for each
sampler on the field sample data sheet (see example in Section
17.0.).
8.5.9 Expose the sampling tubes for the required sampling
period-normally 14-days.
8.5.10 Field blank tubes (see Section 9.3 of Method 325B) are
stored outside the shipping container at representative sampling
locations around the site, but with both long-term storage caps
kept in place throughout the monitoring exercise. Collect at least
two field blanks sorbent samples per sampling period to ensure
sample integrity associated with shipment, collection, and
storage.
8.6 Sorbent Tube Recovery and Meteorological Data Collection
Recover deployed sampling tubes and field blanks as follows:
8.6.1 After the sampling period is complete, immediately replace
the diffusion end cap on each sampled tube with a long-term storage
end cap. Tighten the seal securely by hand and then tighten an
additional quarter turn with an appropriate tool. Record the stop
date and time and any additional relevant information on the sample
data sheet.
8.6.2 Place the sampled tubes, together with the field blanks,
in the storage/shipping container. Label the storage container, but
do not use paints, markers, or adhesive labels to identify the
tubes. TD-compatible electronic (radio frequency identification
(RFID)) tube labels are available commercially and are compatible
with some brands of thermal desorber. If used, these may be
programmed with relevant tube and sample information, which can be
read and automatically transcribed into the sequence report by the
TD system.
Note:
Sampled tubes must not be placed in the same shipping container
as clean conditioned sampling tubes.
8.6.3 Sampled tubes may be shipped at ambient temperature to a
laboratory for sample analysis.
8.6.4 Specify whether the tubes are field blanks or were used
for sampling and document relevant information for each tube using
a Chain of Custody form (see example in Section 17.0) that
accompanies the samples from preparation of the tubes through
receipt for analysis, including the following information: Unique
tube identification numbers for each sampled tube; the date, time,
and location code for each PS placement; the date, time, and
location code for each PS recovery; the GPS reference for each
sampling location; the unique identification number of the
duplicate sample (if applicable); and problems or anomalies
encountered.
8.6.5 If the sorbent tubes are supplied with electronic
(e.g., RFID) tags, it is also possible to allocate a sample
identifier to each PS tube. In this case, the recommended format
for the identification number of each sampled tube is
AA-BB-CC-DD-VOC, where:
AA = Sequence number of placement on route (01, 02, 03 . . .) BB =
Sampling location code (01, 02, 03 . . .) CC = 14-day sample period
number (01 to 26) DD = Sample code (SA = sample, DU = duplicate, FB
= field blank) VOC = 3-letter code for target compound(s)
(
e.g., BNZ for benzene or BTX for benzene, toluene, and
xylenes) Note:
Sampling start and end times/dates can also be logged using RFID
tube tags.
9.0 Quality Control
9.1 Most quality control checks are carried out by the
laboratory and associated requirements are in Section 9.0 of Method
325B, including requirements for laboratory blanks, field blanks,
and duplicate samples.
9.2 Evaluate for potential outliers the laboratory results for
neighboring sampling tubes collected over the same time period. A
potential outlier is a result for which one or more PS tube does
not agree with the trend in results shown by neighboring PS tubes -
particularly when data from those locations have been more
consistent during previous sampling periods. Accidental
contamination by the sample handler must be documented before any
result can be eliminated as an outlier. Rare but possible examples
of contamination include loose or missing storage caps or
contaminated storage/shipping containers. Review data from the same
and neighboring monitoring locations for the subsequent sampling
periods. If the anomalous result is not repeated for that
monitoring location, the episode can be ascribed to transient
contamination and the data in question must be flagged for
potential elimination from the dataset.
9.3 Duplicates and Field Blanks
9.3.1 Collect at least one co-located/duplicate sample for every
10 field samples to determine precision of the measurements.
9.3.2 Collect at least two field blanks sorbent samples per
sampling period to ensure sample integrity associated with
shipment, collection, and storage. You must use the entire sampling
apparatus for field blanks including unopened sorbent tubes mounted
in protective sampling hoods. The tube closures must not be
removed. Field blanks must be placed in two different quadrants
(e.g., 90° and 270°) and remain at the sampling location for
the sampling period.
10.0 Calibration and Standardization
Follow the calibration and standardization procedures for
meteorological measurements in EPA-454/B-08-002 March 2008
(Reference 11) (incorporated by reference - see § 63.14). Refer to
Method 325B for calibration and standardization procedures for
analysis of the passive sampling tubes.
11.0 Analytical Procedures
Refer to Method 325B, which provides details for the preparation
and analysis of sampled passive monitoring tubes (preparation of
sampling tubes, shipment and storage of exposed sampling tubes, and
analysis of sampling tubes).
12.0 Data Analysis, Calculations and Documentation 12.1 Calculate
Annual Average Fenceline Concentration.
After a year's worth of sampling at the facility fenceline (for
example, 26 14-day samples), the average (PSi) may be calculated
for any specified period at each PS location using Equation
12.1.

Where:
PSi = Annual average for location
i. PSip = Sampling period
specific concentration from Method 325B. i = Location of passive
sampler (0 to 360°). p = The sampling period. N = The number of
sampling periods in the year (
e.g., for 14-day sampling
periods, from 1 to 26). Note:
PSip is a function of sampling location-specific factors such as
the contribution from facility sources, unusual localized
meteorological conditions, contribution from nearby interfering
sources, the background caused by integrated far-field sources and
measurement error due to deployment, handling, siting, or
analytical errors.
12.2 Identify Sampling Locations of Interest
If data from neighboring sampling locations are significantly
different, then you may add extra sampling points to isolate
background contributions or identify facility-specific “hot
spots.”
12.3 Evaluate Trends
You may evaluate trends and patterns in the PS data over
multiple sampling periods to determine if elevated concentrations
of target compounds are due to operations on the facility or if
contributions from background sources are significant.
12.3.1 Obtain meteorological data including wind speed and wind
direction or unit vector wind data from the on-site meteorological
station. Use this meteorological data to determine the prevailing
wind direction and speed during the periods of elevated
concentrations.
12.3.2 As an option you may perform preliminary back trajectory
calculations (http://ready.arl.noaa.gov/HYSPLIT.php) to aid
in identifying the source of the background contribution to
elevated target compound concentrations.
12.3.3 Information on published or documented events on- and
off-site may also be included in the associated sampling period
report to explain elevated concentrations if relevant. For example,
you would describe if there was a chemical spill on site, or an
accident on an adjacent road.
12.3.4 Additional monitoring for shorter periods (See section
8.4) may be necessary to allow better discrimination/resolution of
contributing emission sources if the measured trends and associated
meteorology do not provide a clear assessment of facility
contribution to the measured fenceline concentration.
12.3.5 Additional records necessary to calculate sampling period
average target compound concentration can be found in Section 12.1
of Method 325B.
13.0 Method Performance
Method performance requirements are described in Method
325B.
14.0 Pollution Prevention
[Reserved]
15.0 Waste Management
[Reserved]
16.0 References 1. Ambient air quality - Standard method for
measurement of benzene concentrations - Part 4: Diffusive sampling
followed by thermal desorption and gas chromatography, BS EN
14662-4:2005. 2. Thoma, E.D., Miller, C.M., Chung, K.C., Parsons,
N.L. and Shine, B.C. Facility Fence Line Monitoring using Passive
Samplers, J. Air & Waste Mange. Assoc. 2011, 61:834-842. 3. Quality
Assurance Handbook for Air Pollution C Systems, Volume II: Ambient
Air Quality Monitoring Program, EPA-454/B-13-003, May 2013.
Available at
http://www.epa.gov/ttnamti1/files/ambient/pm25/qa/QA-Handbook-Vol-II.pdf.
4. Brown, R.H., Charlton, J. and Saunders, K.J.: The development of
an improved diffusive sampler. Am. Ind. Hyg. Assoc. J. 1981,
42(12): 865-869. 5. Brown, R. H. Environmental use of diffusive
samplers: evaluation of reliable diffusive uptake rates for
benzene, toluene and xylene. J. Environ. Monit. 1999, 1 (1),
115-116. 6. Ballach, J.; Greuter, B.; Schultz, E.; Jaeschke, W.
Variations of uptake rates in benzene diffusive sampling as a
function of ambient conditions. Sci. Total Environ. 1999, 244,
203-217. 7. Brown, R. H. Monitoring the ambient environment with
diffusive samplers: theory and practical considerations. J Environ.
Monit. 2000, 2 (1), 1-9. 8. Buzica, D.; Gerboles, M.; Plaisance, H.
The equivalence of diffusive samplers to reference methods for
monitoring O3, benzene and NO2 in ambient air. J. Environ. Monit.
2008, 10 (9), 1052-1059. 9. Woolfenden, E. Sorbent-based sampling
methods for volatile and semi-volatile organic compounds in air.
Part 2. Sorbent selection and other aspects of optimizing air
monitoring methods. J. Chromatogr. A 2010, 1217, (16), 2685-94. 10.
Pfeffer, H. U.; Breuer, L. BTX measurements with diffusive samplers
in the vicinity of a cokery: Comparison between ORSA-type samplers
and pumped sampling. J. Environ. Monit. 2000, 2 (5), 483-486. 11.
US EPA. 2000. Meteorological Monitoring Guidance for Regulatory
Modeling Applications. EPA-454/R-99-005. Office of Air Quality
Planning and Standards, Research Triangle Park, NC. February 2000.
Available at
http://www.epa.gov/scram001/guidance/met/mmgrma.pdf. 12.
Quality Assurance Handbook for Air Pollution Measurement Systems.
Volume IV: Meteorological Measurements Version 2.0 Final,
EPA-454/B-08-002 March 2008. Available at
http://www.epa.gov/ttnamti1/files/ambient/met/
Volume%20IV_Meteorological_ Measurements.pdf. 13. ISO
16017-2:2003(E), Indoor, ambient and workplace air - Sampling and
analysis of volatile organic compounds by sorbent tube/thermal
desorption/capillary gas chromatography. Part 2: Diffusive
sampling. 14. ASTM D6196-03 (Reapproved 2009): Standard practice
for selection of sorbents, sampling, and thermal desorption
analysis procedures for volatile organic compounds in air. 17.0
Tables, Diagrams, Flowcharts and Validation Data

Method 325B -
Volatile Organic Compounds from Fugitive and Area Sources: Sampler
Preparation and Analysis 1.0 Scope and Application
1.1 This method describes thermal desorption/gas chromatography
(TD/GC) analysis of volatile organic compounds (VOCs) from fugitive
and area emission sources collected onto sorbent tubes using
passive sampling. It could also be applied to the TD/GC analysis of
VOCs collected using active (pumped) sampling onto sorbent tubes.
The concentration of airborne VOCs at or near potential fugitive-
or area-emission sources may be determined using this method in
combination with Method 325A. Companion Method 325A (Sampler
Deployment and VOC Sample Collection) describes procedures for
deploying the sorbent tubes and passively collecting VOCs.
1.2 The preferred GC detector for this method is a mass
spectrometer (MS), but flame ionization detectors (FID) may also be
used. Other conventional GC detectors such as electron capture
(ECD), photoionization (PID), or flame photometric (FPD) may also
be used if they are selective and sensitive to the target
compound(s) and if they meet the method performance criteria
provided in this method.
1.3 There are 97 VOCs listed as hazardous air pollutants in
Title III of the Clean Air Act Amendments of 1990. Many of these
VOC are candidate compounds for this method. Compounds with known
uptake rates for Carbograph TM 1 TD, Carbopack TM B, or Carbopack
TM X are listed in Table 12.1. This method provides performance
criteria to demonstrate acceptable performance of the method (or
modifications of the method) for monitoring one or more of the
compounds listed Table 12.1. If standard passive sampling tubes are
packed with other sorbents or used for other analytes than those
listed in Table 12.1, then method performance and relevant uptake
rates should be verified according to Addendum A to this method or
by one of the following national/international standard methods:
ISO 16017-2:2003(E), ASTM D6196-03 (Reapproved 2009), or BS EN
14662-4:2005 (all incorporated by reference - see § 63.14), or
reported in the peer-reviewed open literature.
1.4 The analytical approach using TD/GC/MS is based on
previously published EPA guidance in Compendium Method TO-17
(http://www.epa.gov/ttnamti1/airtox.html#compendium)
(Reference 1), which describes active (pumped) sampling of VOCs
from ambient air onto tubes packed with thermally stable
adsorbents.
1.5 Inorganic gases not suitable for analysis by this method
include oxides of carbon, nitrogen and sulfur, ozone (O3), and
other diatomic permanent gases. Other pollutants not suitable for
this analysis method include particulate pollutants, (i.e.,
fumes, aerosols, and dusts), compounds too labile (reactive) for
conventional GC analysis, and VOCs that are more volatile than
propane.
2.0 Summary of Method
2.1 This method provides procedures for the preparation,
conditioning, blanking, and shipping of sorbent tubes prior to
sample collection.
2.2 Laboratory and field personnel must have experience of
sampling trace-level VOCs using sorbent tubes (References 2,5) and
must have experience operating thermal desorption/GC/multi-detector
instrumentation.
2.3 Key steps of this method as implemented for each sample tube
include: Stringent leak testing under stop flow, recording ambient
temperature conditions, adding internal standards, purging the
tube, thermally desorbing the sampling tube, refocusing on a
focusing trap, desorbing and transferring/injecting the VOCs from
the secondary trap into the capillary GC column for separation and
analysis.
2.4 Water management steps incorporated into this method
include: (a) Selection of hydrophobic sorbents in the sampling
tube; (b) optional dry purging of sample tubes prior to analysis;
and (c) additional selective elimination of water during primary
(tube) desorption (if required) by selecting trapping sorbents and
temperatures such that target compounds are quantitatively retained
while water is purged to vent.
3.0 Definitions
(See also Section 3.0 of Method 325A).
3.1 Blanking is the desorption and confirmatory analysis of
conditioned sorbent tubes before they are sent for field
sampling.
3.2 Breakthrough volume and associated relation to passive
sampling. Breakthrough volumes, as applied to active sorbent
tube sampling, equate to the volume of air containing a constant
concentration of analyte that may be passed through a sorbent tube
at a given temperature before a detectable level (5 percent) of the
input analyte concentration elutes from the tube. Although
breakthrough volumes are directly related to active rather than
passive sampling, they provide a measure of the strength of the
sorbent-sorbate interaction and therefore also relate to the
efficiency of the passive sampling process. The best direct measure
of passive sampling efficiency is the stability of the uptake rate.
Quantitative passive sampling is compromised when the sorbent no
longer acts as a perfect sink - i.e., when the concentration
of a target analyte immediately above the sorbent sampling surface
no longer approximates to zero. This causes a reduction in the
uptake rate over time. If the uptake rate for a given analyte on a
given sorbent tube remains relatively constant - i.e., if
the uptake rate determined for 48 hours is similar to that
determined for 7 or 14 days - the user can be confident that
passive sampling is occurring at a constant rate. As a general rule
of thumb, such ideal passive sampling conditions typically exist
for analyte:sorbent combinations where the breakthrough volume
exceeds 100 L (Reference 4).
3.3 Continuing calibration verification sample (CCV).
Single level calibration samples run periodically to confirm that
the analytical system continues to generate sample results within
acceptable agreement to the current calibration curve.
3.4 Focusing trap is a cooled, secondary sorbent trap
integrated into the analytical thermal desorber. It typically has a
smaller i.d. and lower thermal mass than the original sample tube
allowing it to effectively refocus desorbed analytes and then heat
rapidly to ensure efficient transfer/injection into the capillary
GC analytical column.
3.5 High Resolution Capillary Column Chromatography uses
fused silica capillary columns with an inner diameter of 320 µm or
less and with a stationary phase film thickness of 5 µm or
less.
3.6 h is time in hours.
3.7 i.d. is inner diameter.
3.8 min is time in minutes.
3.9 Method Detection Limit is the lowest level of analyte
that can be detected in the sample matrix with 99% confidence.
3.10 MS-SCAN is the mode of operation of a GC quadrupole
mass spectrometer detector that measures all ions over a given mass
range over a given period of time.
3.11 MS-SIM is the mode of operation of a GC quadrupole
mass spectrometer detector that measures only a single ion or a
selected number of discrete ions for each analyte.
3.12 o.d. is outer diameter.
3.13 ppbv is parts per billion by volume.
3.14 Thermal desorption is the use of heat and a flow of
inert (carrier) gas to extract volatiles from a solid matrix. No
solvent is required.
3.15 Total ion chromatogram is the chromatogram produced
from a mass spectrometer detector collecting full spectral
information.
3.16 Two-stage thermal desorption is the process of
thermally desorbing analytes from a sorbent tube, reconcentrating
them on a focusing trap (see Section 3.4), which is then itself
rapidly heated to “inject” the concentrated compounds into the GC
analyzer.
3.17 VOC is volatile organic compound.
4.0 Analytical Interferences
4.1 Interference from Sorbent Artifacts. Artifacts may
include target analytes as well as other VOC that co-elute
chromatographically with the compounds of interest or otherwise
interfere with the identification or quantitation of target
analytes.
4.1.1 Sorbent decomposition artifacts are VOCs that form when
sorbents degenerate, e.g., when exposed to reactive species
during sampling. For example, benzaldehyde, phenol, and
acetophenone artifacts are reported to be formed via oxidation of
the polymeric sorbent Tenax® when sampling high concentration
(100-500 ppb) ozone atmospheres (Reference 5).
4.1.2 Preparation and storage artifacts are VOCs that were not
completely cleaned from the sorbent tube during conditioning or
that are an inherent feature of that sorbent at a given
temperature.
4.2 Humidity. Moisture captured during sampling can
interfere with VOC analysis. Passive sampling using tubes packed
with hydrophobic sorbents, like those described in this method,
minimizes water retention. However, if water interference is found
to be an issue under extreme conditions, one or more of the water
management steps described in Section 2.4 can be applied.
4.3 Contamination from Sample Handling. The type of
analytical thermal desorption equipment selected should exclude the
possibility of outer tube surface contamination entering the sample
flow path (see Section 6.6). If the available system does not meet
this requirement, sampling tubes and caps must be handled only
while wearing clean, white cotton or powder free nitrile gloves to
prevent contamination with body oils, hand lotions, perfumes,
etc.
5.0 Safety
5.1 This method does not address all of the safety concerns
associated with its use. It is the responsibility of the user of
this standard to establish appropriate field and laboratory safety
and health practices prior to use.
5.2 Laboratory analysts must exercise extreme care in working
with high-pressure gas cylinders.
5.3 Due to the high temperatures involved, operators must use
caution when conditioning and analyzing tubes.
6.0 Equipment and Supplies
6.1 Tube Dimensions and Materials. The sampling tubes for
this method are 3.5-inches (89 mm) long, 1/4 inch (6.4 mm) o.d.,
and 5 mm i.d. passive sampling tubes (see Figure 6.1). The tubes
are made of inert-coated stainless steel with the central section
(up to 60 mm) packed with sorbent, typically supported between two
100 mesh stainless steel gauze. The tubes have a cross sectional
area of 19.6 square mm (5 mm i.d.). When used for passive sampling,
these tubes have an internal diffusion (air) gap (DG) of 1.5 cm
between the sorbent retaining gauze at the sampling end of the
tube, and the gauze in the diffusion cap.

6.2 Tube
Conditioning Apparatus
6.2.1 Freshly packed or newly purchased tubes must be
conditioned as described in Section 9 using an appropriate
dedicated tube conditioning unit or the thermal desorber. Note that
the analytical TD system should be used for tube conditioning if it
supports a dedicated tube conditioning mode in which effluent from
contaminated tubes is directed to vent without passing through key
parts of the sample flow path such as the focusing trap.
6.2.2 Dedicated tube conditioning units must be leak-tight to
prevent air ingress, allow precise and reproducible temperature
selection (±5 °C), offer a temperature range at least as great as
that of the thermal desorber, and support inert gas flows in the
range up to 100 mL/min.
Note:
For safety and to avoid laboratory contamination, effluent gases
from freshly packed or highly contaminated tubes should be passed
through a charcoal filter during the conditioning process to
prevent desorbed VOCs from polluting the laboratory atmosphere.
6.3 Tube Labeling
6.3.1 Label the sample tubes with a unique permanent
identification number and an indication of the sampling end of the
tube. Labeling options include etching and TD-compatible electronic
(radio frequency identification (RFID)) tube labels.
6.3.2 To avoid contamination, do not make ink markings of any
kind on clean sorbent tubes or apply adhesive labels.
Note:
TD-compatible electronic (RFID) tube labels are available
commercially and are compatible with some brands of thermal
desorber. If used, these may be programmed with relevant tube and
sample information, which can be read and automatically transcribed
into the sequence report by the TD system (see Section 8.6 of
Method 325A).
6.4 Blank and Sampled Tube Storage Apparatus
6.4.1 Long-term storage caps. Seal clean, blank and sampled
sorbent tubes using inert, long-term tube storage caps comprising
non-greased, 2-piece, 0.25-inch, metal SwageLok®-type screw caps
fitted with combined polytetrafluoroethylene ferrules.
6.4.2 Storage and transportation containers. Use clean glass
jars, metal cans or rigid, non-emitting polymer boxes.
Note:
You may add a small packet of new activated charcoal or
charcoal/silica gel to the shipping container for storage and
transportation of batches of conditioned sorbent tubes prior to
use. Coolers without ice packs make suitable shipping boxes for
containers of tubes because the coolers help to insulate the
samples from extreme temperatures (e.g., if left in a parked
vehicle).
6.5 Unheated GC Injection Unit for Loading Standards Onto Blank
Tubes
A suitable device has a simple push fit or finger-tightening
connector for attaching the sampling end of blank sorbent tubes
without damaging the tube. It also has a means of controlling
carrier gas flow through the injector and attached sorbent tube at
50-100 mL/min and includes a low emission septum cap that allows
the introduction of gas or liquid standards via appropriate
syringes. Reproducible and quantitative transfer of higher boiling
compounds in liquid standards is facilitated if the injection unit
allows the tip of the syringe to just touch the sorbent retaining
gauze inside the tube.
6.6 Thermal Desorption Apparatus
The manual or automated thermal desorption system must heat
sorbent tubes while a controlled flow of inert (carrier) gas passes
through the tube and out of the sampling end. The apparatus must
also incorporate a focusing trap to quantitatively refocus
compounds desorbed from the tube. Secondary desorption of the
focusing trap should be fast/efficient enough to transfer the
compounds into the high resolution capillary GC column without band
broadening and without any need for further pre- or on-column
focusing. Typical TD focusing traps comprise small sorbent traps
(Reference 16) that are electrically-cooled using multistage
Peltier cells (References 17, 18). The direction of gas flow during
trap desorption should be the reverse of that used for focusing to
extend the compatible analyte volatility range. Closed cycle
coolers offer another cryogen-free trap cooling option. Other TD
system requirements and operational stages are described in Section
11 and in Figures 17-2 through 17-4.
6.7 Thermal Desorber - GC Interface
6.7.1 The interface between the thermal desorber and the GC must
be heated uniformly and the connection between the transfer line
insert and the capillary GC analytical column itself must be leak
tight.
6.7.2 A portion of capillary column can alternatively be
threaded through the heated transfer line/TD interface and
connected directly to the thermal desorber.
Note:
Use of a metal syringe-type needle or unheated length of fused
silica pushed through the septum of a conventional GC injector is
not permitted as a means of interfacing the thermal desorber to the
chromatograph. Such connections result in cold spots, cause band
broadening and are prone to leaks.
6.8 GC/MS Analytical Components
6.8.1 The GC system must be capable of temperature programming
and operation of a high resolution capillary column. Depending on
the choice of column (e.g., film thickness) and the
volatility of the target compounds, it may be necessary to cool the
GC oven to subambient temperatures (e.g., −50 °C) at the
start of the run to allow resolution of very volatile organic
compounds.
6.8.2 All carrier gas lines supplying the GC must be constructed
from clean stainless steel or copper tubing.
Non-polytetrafluoroethylene thread sealants. Flow controllers,
cylinder regulators, or other pneumatic components fitted with
rubber components are not suitable.
6.9 Chromatographic Columns
High-resolution, fused silica or equivalent capillary columns
that provide adequate separation of sample components to permit
identification and quantitation of target compounds must be
used.
Note:
100-percent methyl silicone or 5-percent phenyl, 95-percent
methyl silicone fused silica capillary columns of 0.25- to 0.32-mm
i.d. of varying lengths and with varying thicknesses of stationary
phase have been used successfully for non-polar and moderately
polar compounds. However, given the diversity of potential target
lists, GC column choice is left to the operator, subject to the
performance criteria of this method.
6.10 Mass Spectrometer
Linear quadrupole, magnetic sector, ion trap or time-of-flight
mass spectrometers may be used provided they meet specified
performance criteria. The mass detector must be capable of
collecting data from 35 to 300 atomic mass units (amu) every 1
second or less, utilizing 70 volts (nominal) electron energy in the
electron ionization mode, and producing a mass spectrum that meets
all the instrument performance acceptance criteria in Section 9
when 50 ηg or less of p-bromofluorobenzene is analyzed.
7.0 Reagents and Standards 7.1 Sorbent Selection
7.1.1 Use commercially packed tubes meeting the requirements of
this method or prepare tubes in the laboratory using sieved
sorbents of particle size in the range 20 to 80 mesh that meet the
retention and quality control requirements of this method.
7.1.2 This passive air monitoring method can be used without the
evaluation specified in Addendum A if the type of tubes described
in Section 6.1 are packed with 4-6 cm (typically 400-650 mg) of the
sorbents listed in Table 12.1 and used for the respective target
analytes.
Note:
Although Carbopack TM X is the optimum sorbent choice for
passive sampling of 1,3-butadiene, recovery of compounds with vapor
pressure lower than benzene may be difficult to achieve without
exceeding sorbent maximum temperature limitations (see Table 8.1).
See ISO 16017-2:2003(E) or ASTM D6196-03 (Reapproved 2009) (both
incorporated by reference - see § 63.14) for more details on
sorbent choice for air monitoring using passive sampling tubes.
7.1.3 If standard passive sampling tubes are packed with other
sorbents or used for analytes other than those tabulated in Section
12.0, method performance and relevant uptake rates should be
verified according to Addendum A to this method or by following the
techniques described in one of the following national/international
standard methods: ISO 16017-2:2003(E), ASTM D6196-03 (Reapproved
2009), or BS EN 14662-4:2005 (all incorporated by reference - see §
63.14) - or reported in the peer-reviewed open literature. A
summary table and the supporting evaluation data demonstrating the
selected sorbent meets the requirements in Addendum A to this
method must be submitted to the regulatory authority as part of a
request to use an alternative sorbent.
7.1.4 Passive (diffusive) sampling and thermal desorption
methods that have been evaluated at relatively high atmospheric
concentrations (i.e., mid-ppb to ppm) and published for use
in workplace air and industrial/mobile source emissions testing
(References 9-20) may be applied to this procedure. However, the
validity of any shorter term uptake rates must be verified and
adjusted if necessary for the longer monitoring periods required by
this method by following procedures described in Addendum A to this
method or those presented in national/international standard
methods: ISO 16017-2:2003(E), ASTM D6196-03 (Reapproved 2009), or
BS EN 14662-4:2005 (all incorporated by reference-see § 63.14).
7.1.5 Suitable sorbents for passive sampling must have
breakthrough volumes of at least 20 L (preferably >100 L) for
the compounds of interest and must quantitatively release the
analytes during desorption without exceeding maximum temperatures
for the sorbent or instrumentation.
7.1.6 Repack/replace the sorbent tubes or demonstrate tube
performance following the requirements in Addendum A to this method
at least every 2 years or every 50 uses, whichever occurs
first.
7.2 Gas Phase Standards
7.2.1 Static or dynamic standard atmospheres may be used to
prepare calibration tubes and/or to validate passive sampling
uptake rates and can be generated from pure chemicals or by
diluting concentrated gas standards. The standard atmosphere must
be stable at ambient pressure and accurate to ±10 percent of the
target gas concentration. It must be possible to maintain standard
atmosphere concentrations at the same or lower levels than the
target compound concentration objectives of the test. Test
atmospheres used for validation of uptake rates must also contain
at least 35 percent relative humidity.
Note:
Accurate, low-(ppb-) level gas-phase VOC standards are difficult
to generate from pure materials and may be unstable depending on
analyte polarity and volatility. Parallel monitoring of vapor
concentrations with alternative methods, such as pumped sorbent
tubes or sensitive/selective on-line detectors, may be necessary to
minimize uncertainty. For these reasons, standard atmospheres are
rarely used for routine calibration.
7.2.2 Concentrated, pressurized gas phase standards. Accurate
(±5 percent or better), concentrated gas phase standards supplied
in pressurized cylinders may also be used for calibration. The
concentration of the standard should be such that a 0.5-5.0 mL
volume contains approximately the same mass of analytes as will be
collected from a typical air sample.
7.2.3 Follow manufacturer's guidelines concerning storage
conditions and recertification of the concentrated gas phase
standard. Gas standards must be recertified a minimum of once every
12 months.
7.3 Liquid Standards
Target analytes can also be introduced to the sampling end of
sorbent tubes in the form of liquid calibration standards.
7.3.1 The concentration of liquid standards must be such that an
injection of 0.5-2 µl of the solution introduces the same mass of
target analyte that is expected to be collected during the passive
air sampling period.
7.3.2 Solvent Selection. The solvent selected for the liquid
standard must be pure (contaminants <10 percent of minimum
analyte levels) and must not interfere chromatographically with the
compounds of interest.
7.3.3 If liquid standards are sourced commercially, follow
manufacturer's guidelines concerning storage conditions and shelf
life of unopened and opened liquid stock standards.
Note:
Commercial VOC standards are typically supplied in volatile or
non-interfering solvents such as methanol.
7.3.4 Working standards must be stored at 6 °C or less and used
or discarded within two weeks of preparation.
7.4 Gas Phase Internal Standards
7.4.1 Gas-phase deuterated or fluorinated organic compounds may
be used as internal standards for MS-based systems.
7.4.2 Typical compounds include deuterated toluene,
perfluorobenzene and perfluorotoluene.
7.4.3 Use multiple internal standards to cover the volatility
range of the target analytes.
7.4.4 Gas-phase standards must be obtained in pressurized
cylinders and containing vendor certified gas concentrations
accurate to ±5 percent. The concentration should be such that the
mass of internal standard components introduced is similar to those
of the target analytes collected during field monitoring.
7.5 Preloaded Standard Tubes
Certified, preloaded standard tubes, accurate within ±5 percent
for each analyte at the microgram level and ±10 percent at the
nanogram level, are available commercially and may be used for
auditing and quality control purposes. (See Section 9.5 for audit
accuracy evaluation criteria.) Certified preloaded tubes may also
be used for routine calibration.
Note:
Proficiency testing schemes are also available for TD/GC/MS
analysis of sorbent tubes preloaded with common analytes such as
benzene, toluene, and xylene.
7.6 Carrier Gases
Use inert, 99.999-percent or higher purity helium as carrier
gas. Oxygen and organic filters must be installed in the carrier
gas lines supplying the analytical system according to the
manufacturer's instructions. Keep records of filter and oxygen
scrubber replacement.
8.0 Sorbent Tube Handling (Before and After Sampling) 8.1 Sample
Tube Conditioning
8.1.1 Sampling tubes must be conditioned using the apparatus
described in Section 6.2.
8.1.2 New tubes should be conditioned for 2 hours to supplement
the vendor's conditioning procedure. Recommended temperatures for
tube conditioning are given in Table 8.1.
8.1.3 After conditioning, the blank must be verified on each new
sorbent tube and on 10 percent of each batch of reconditioned
tubes. See Section 9.0 for acceptance criteria.
Table 8.1 - Example Sorbent Tube
Conditioning Parameters
Sampling sorbent |
Maximum
temperature
( °C) |
Conditioning temperature
( °C) |
Carrier gas flow rate |
Carbotrap® C |
>400 |
350 |
100 mL/min |
Carbopack
TM C |
|
|
|
Anasorb® GCB2 |
|
|
|
Carbograph
TM 1 TD |
|
|
|
Carbotrap® |
|
|
|
Carbopack
TM B |
|
|
|
Anasorb® GCB1 |
|
|
|
Tenax® TA
Carbopack TM X |
350 |
330 |
100 mL/min |
8.2 Capping, Storage and Shipment of Conditioned Tubes
8.2.1 Conditioned tubes must be sealed using long-term storage
caps (see Section 6.4) pushed fully down onto both ends of the PS
sorbent tube, tightened by hand and then tighten an additional
quarter turn using an appropriate tool.
8.2.2 The capped tubes must be kept in appropriate containers
for storage and transportation (see Section 6.4.2). Containers of
sorbent tubes may be stored and shipped at ambient temperature and
must be kept in a clean environment.
8.2.3 You must keep batches of capped tubes in their shipping
boxes or wrap them in uncoated aluminum foil before placing them in
their storage container, especially before air freight, because the
packaging helps hold caps in position if the tubes get very
cold.
8.3 Calculating the Number of Tubes Required for a Monitoring
Exercise
8.3.1 Follow guidance given in Method 325A to determine the
number of tubes required for site monitoring.
8.3.2 The following additional samples will also be required:
Laboratory blanks as specified in Section 9.1.2 (one per analytical
sequence minimum), field blanks as specified in Section 9.3.2 (two
per sampling period minimum), CCV tubes as specified in Section
10.9.4. (at least one per analysis sequence or every 24 hours), and
duplicate samples as specified in Section 9.4 (at least one
duplicate sample is required for every 10 sampling locations during
each monitoring period).
8.4 Sample Collection
8.4.1 Allow the tubes to equilibrate with ambient temperature
(approximately 30 minutes to 1 hour) at the monitoring location
before removing them from their storage/shipping container for
sample collection.
8.4.2 Tubes must be used for sampling within 30 days of
conditioning (Reference 4).
8.4.3 During field monitoring, the long-term storage cap at the
sampling end of the tube is replaced with a diffusion cap and the
whole assembly is arranged vertically, with the sampling end
pointing downward, under a protective hood or shield - See Section
6.1 of Method 325A for more details.
8.5 Sample Storage
8.5.1 After sampling, tubes must be immediately resealed with
long-term storage caps and placed back inside the type of storage
container described in Section 6.4.2.
8.5.2 Exposed tubes may not be placed in the same container as
clean tubes. They should not be taken back out of the container
until ready for analysis and after they have had time to
equilibrate with ambient temperature in the laboratory.
8.5.3 Sampled tubes must be inspected before analysis to
identify problems such as loose or missing caps, damaged tubes,
tubes that appear to be leaking sorbent or container contamination.
Any and all such problems must be documented together with the
unique identification number of the tube or tubes concerned.
Affected tubes must not be analyzed but must be set aside.
8.5.4 Intact tubes must be analyzed within 30 days of the end of
sample collection (within one week for limonene, carene,
bis-chloromethyl ether, labile sulfur or nitrogen-containing
compounds, and other reactive VOCs).
Note:
Ensure ambient temperatures stay below 23 °C during
transportation and storage. Refrigeration is not normally required
unless the samples contain reactive compounds or cannot be analyzed
within 30 days. If refrigeration is used, the atmosphere inside the
refrigerator must be clean and free of organic solvents.
9.0 Quality Control 9.1 Laboratory Blank
The analytical system must be demonstrated to be contaminant
free by performing a blank analysis at the beginning of each
analytical sequence to demonstrate that the secondary trap and
TD/GC/MS analytical equipment are free of any significant
interferents.
9.1.1 Laboratory blank tubes must be prepared from tubes that
are identical to those used for field sampling.
9.1.2 Analysis of at least one laboratory blank is required per
analytical sequence. The laboratory blank must be stored in the
laboratory under clean, controlled ambient temperature
conditions.
9.1.3 Laboratory blank/artifact levels must meet the
requirements of Section 9.2.2 (see also Table 17.1). If the
laboratory blank does not meet requirements, stop and perform
corrective actions and then re-analyze laboratory blank to ensure
it meets requirements.
9.2 Tube Conditioning
9.2.1 Conditioned tubes must be demonstrated to be free of
contaminants and interference by running 10 percent of the blank
tubes selected at random from each conditioned batch under standard
sample analysis conditions (see Section 8.1).
9.2.2 Confirm that artifacts and background contamination are ≤
0.2 ppbv or less than three times the detection limit of the
procedure or less than 10 percent of the target compound(s) mass
that would be collected if airborne concentrations were at the
regulated limit value, whichever is larger. Only tubes that meet
these criteria can be used for field monitoring, field or
laboratory blanks, or for system calibration.
9.2.3 If unacceptable levels of VOCs are observed in the tube
blanks, then the processes of tube conditioning and checking the
blanks must be repeated.
9.3 Field Blanks
9.3.1 Field blank tubes must be prepared from tubes that are
identical to those used for field sampling - i.e., they
should be from the same batch, have a similar history, and be
conditioned at the same time.
9.3.2 Field blanks must be shipped to the monitoring site with
the sampling tubes and must be stored at the sampling location
throughout the monitoring exercise. The field blanks must be
installed under a protective hood/cover at the sampling location,
but the long-term storage caps must remain in place throughout the
monitoring period (see Method 325A). The field blanks are then
shipped back to the laboratory in the same container as the sampled
tubes. Collect at least two field blank samples per sampling period
to ensure sample integrity associated with shipment, collection,
and storage.
9.3.3 Field blanks must contain no greater than one-third of the
measured target analyte or compliance limit for field samples (see
Table 17.1). If either field blank fails, flag all data that do not
meet this criterion with a note that the associated results are
estimated and likely to be biased high due to field blank
background.
9.4 Duplicate Samples
Duplicate (co-located) samples collected must be analyzed and
reported as part of method quality control. They are used to
evaluate sampling and analysis precision. Relevant performance
criteria are given in Section 9.9.
9.5 Method Performance Criteria
Unless otherwise noted, monitoring method performance
specifications must be demonstrated for the target compounds using
the procedures described in Addendum A to this method and the
statistical approach presented in Method 301.
9.6 Method Detection Limit
Determine the method detection limit under the analytical
conditions selected (see Section 11.3) using the procedure in
Section 15 of Method 301. The method detection limit is defined for
each system by making seven replicate measurements of a
concentration of the compound of interest within a factor of five
of the detection limit. Compute the standard deviation for the
seven replicate concentrations, and multiply this value by three.
The results should demonstrate that the method is able to detect
analytes such as benzene at concentrations as low as 50 ppt or
1/3rd (preferably 1/10th) of the lowest concentration of interest,
whichever is larger.
Note:
Determining the detection limit may be an iterative process as
described in 40 CFR part 136, Appendix B.
9.7 Analytical Bias
Analytical bias must be demonstrated to be within ±30 percent
using Equation 9.1. Analytical bias must be demonstrated during
initial setup of this method and as part of the CCV carried out
with every sequence of 10 samples or less (see Section 9.14).
Calibration standard tubes (see Section 10.0) may be used for this
purpose.

Eq. 9.1
Where: Spiked Value = A known mass of VOCs added to the tube.
Measured Value = Mass determined from analysis of the tube. 9.8
Analytical Precision
Demonstrate an analytical precision within ±20 percent using
Equation 9.2. Analytical precision must be demonstrated during
initial setup of this method and at least once per year.
Calibration standard tubes may be used (see Section 10.0) and data
from CCV may also be applied for this purpose.

Eq. 9.2
Where: A1 = A measurement value taken from one spiked tube. A2 = A
measurement value taken from a second spiked tube. A = The average
of A1 and A2. 9.9 Field Replicate Precision
Use Equation 9.3 to determine and report replicate precision for
duplicate field samples (see Section 9.4). The level of agreement
between duplicate field samples is a measure of the precision
achievable for the entire sampling and analysis procedure. Flag
data sets for which the duplicate samples do not agree within 30
percent.

Eq. 9.3
Where: F1 = A measurement value (mass) taken from one of the two
field replicate tubes used in sampling. F2 = A measurement value
(mass) taken from the second of two field replicate tubes used in
sampling. F = The average of F1 and F2. 9.10 Desorption Efficiency
and Compound Recovery
The efficiency of the thermal desorption method must be
determined.
9.10.1 Quantitative (>95 percent) compound recovery must be
demonstrated by repeat analyses on a same standard tube.
9.10.2 Compound recovery through the TD system can also be
demonstrated by comparing the calibration check sample response
factor obtained from direct GC injection of liquid standards with
that obtained from thermal desorption analysis response factor
using the same column under identical conditions.
9.10.3 If the relative response factors obtained for one or more
target compounds introduced to the column via thermal desorption
fail to meet the criteria in Section 9.10.1, you must adjust the TD
parameters to meet the criteria and repeat the experiment. Once the
thermal desorption conditions have been optimized, you must repeat
this test each time the analytical system is recalibrated to
demonstrate continued method performance.
9.11 Audit Samples
Certified reference standard samples must be used to audit this
procedure (if available). Accuracy within 30 percent must be
demonstrated for relevant ambient air concentrations (0.5 to 25
ppb).
9.12 Mass Spectrometer Tuning Criteria
Tune the mass spectrometer (if used) according to manufacturer's
specifications. Verify the instrument performance by analyzing a 50
ηg injection of bromofluorobenzene. Prior to the beginning of each
analytical sequence or every 24 hours during continuous GC/MS
operation for this method demonstrate that the bromofluorobenzene
tuning performance criteria in Table 9.1 have been met.
Table 9.1 - GC/MS Tuning Criteria
1
Target mass |
Rel. to mass |
Lower limit % |
Upper limit % |
50 |
95 |
8 |
40 |
75 |
95 |
30 |
66 |
95 |
95 |
100 |
100 |
96 |
95 |
5 |
9 |
173 |
174 |
0 |
2 |
174 |
95 |
50 |
120 |
175 |
174 |
4 |
9 |
176 |
174 |
93 |
101 |
177 |
176 |
5 |
9 |
9.13 Routine CCV at the Start of a Sequence
Run CCV before each sequence of analyses and after every tenth
sample to ensure that the previous multi-level calibration (see
section 10.0) is still valid.
9.13.1 The sample concentration used for the CCV should be near
the mid-point of the multi-level calibration range.
9.13.2 Quantitation software must be updated with response
factors determined from the CCV standard. The percent deviation
between the initial calibration and the CCV for all compounds must
be within 30 percent.
9.14 CCV at the End of a Sequence
Run another CCV after running each sequence of samples. The
initial CCV for a subsequent set of samples may be used as the
final CCV for a previous analytical sequence, provided the same
analytical method is used and the subsequent set of samples is
analyzed immediately (within 4 hours) after the last CCV.
9.15 Additional Verification
Use a calibration check standard from a second, separate source
to verify the original calibration at least once every three
months.
9.16 Integration Method
Document the procedure used for integration of analytical data
including field samples, calibration standards and blanks.
9.17 QC Records
Maintain all QC reports/records for each TD/GC/MS analytical
system used for application of this method. Routine quality control
requirements for this method are listed below and summarized in
Table 17.1.
10.0 Calibration and Standardization
10.1 Calibrate the analytical system using standards covering
the range of analyte masses expected from field samples.
10.2 Analytical results for field samples must fall within the
calibrated range of the analytical system to be valid.
10.3 Calibration standard preparation must be fully traceable to
primary standards of mass and/or volume, and/or be confirmed using
an independent certified reference method.
10.3.1 Preparation of calibration standard tubes from standard
atmospheres.
10.3.1.1 Subject to the requirements in Section 7.2.1, low-level
standard atmospheres may be introduced to clean, conditioned
sorbent tubes in order to produce calibration standards.
10.3.1.2 The standard atmosphere generator or system must be
capable of producing sufficient flow at a constant rate to allow
the required analyte mass to be introduced within a reasonable time
frame and without affecting the concentration of the standard
atmosphere itself.
10.3.1.3 The sampling manifold may be heated to minimize risk of
condensation but the temperature of the gas delivered to the
sorbent tubes may not exceed 100 °F.
10.3.1.4 The flow rates passed through the tube should be in the
order of 50-100 mL/min and the volume of standard atmosphere
sampled from the manifold or chamber must not exceed the
breakthrough volume of the sorbent at the given temperature.
10.4 Preparation of calibration standard tubes from concentrated
gas standards.
10.4.1 If a suitable concentrated gas standard (see Section
7.2.2) can be obtained, follow the manufacturer's recommendations
relating to suitable storage conditions and product lifetime.
10.4.2 Introduce precise 0.5 to 500.0 mL aliquots of the
standard to the sampling end of conditioned sorbent tubes in a
50-100 mL/min flow of pure carrier gas.
Note:
This can be achieved by connecting the sampling end of the tube
to an unheated GC injector (see Section 6.6) and introducing the
aliquot of gas using a suitable gas syringe. Gas sample valves
could alternatively be used to meter the standard gas volume.
10.4.3 Each sorbent tube should be left connected to the flow of
gas for 2 minutes after standard introduction. As soon as each
spiked tube is removed from the injection unit, seal it with
long-term storage caps and place it in an appropriate tube
storage/transportation container if it is not to be analyzed within
24 hours.
10.5 Preparation of calibration standard tubes from liquid
standards.
10.5.1 Suitable standards are described in Section 7.3.
10.5.2 Introduce precise 0.5 to 2 µl aliquots of liquid
standards to the sampling end of sorbent tubes in a flow (50-100
mL/min) of carrier gas using a precision syringe and an unheated
injector (Section 6.5). The flow of gas should be sufficient to
completely vaporize the liquid standard.
Note:
If the analytes of interest are higher boiling than n-decane,
reproducible analyte transfer to the sorbent bed is optimized by
allowing the tip of the syringe to gently touch the sorbent
retaining gauze at the sampling end of the tube.
10.5.3 Each sorbent tube is left connected to the flow of gas
for 5 minutes after liquid standard introduction.
10.5.3.1 As soon as each spiked tube is removed from the
injection unit, seal it with long-term storage caps and place it in
an appropriate tube storage container if it is not to be analyzed
within 24 hours.
Note:
In cases where it is possible to selectively purge the solvent
from the tube while all target analytes are quantitatively
retained, a larger 2 µL injection may be made for optimum accuracy.
However, if the solvent cannot be selectively purged and will be
present during analysis, the injection volume should be as small as
possible (e.g., 0.5 µL) to minimize solvent
interference.
Note:
This standard preparation technique requires the entire liquid
plug including the tip volume be brought into the syringe barrel.
The volume in the barrel is recorded, the syringe is inserted into
the septum of the spiking apparatus. The liquid is then quickly
injected. Any remaining liquid in the syringe tip is brought back
into the syringe barrel. The volume in the barrel is recorded and
the amount spiked onto the tube is the difference between the
before spiking volume and the after spiking volume. A bias occurs
with this method when sample is drawn continuously up into the
syringe to the specified volume and the calibration solution in the
syringe tip is ignored.
10.6 Preparation of calibration standard tubes from multiple
standards.
10.6.1 If it is not possible to prepare one standard containing
all the compounds of interest (e.g., because of chemical
reactivity or the breadth of the volatility range), standard tubes
can be prepared from multiple gas or liquid standards.
10.6.2 Follow the procedures described in Sections 10.4 and
10.5, respectively, for introducing each gas and/or liquid standard
to the tube and load those containing the highest boiling compounds
of interest first and the lightest species last.
10.7 Additional requirements for preparation of calibration
tubes.
10.7.1 Storage of Calibration Standard Tubes
10.7.1.1 Seal tubes with long-term storage caps immediately
after they have been disconnected from the standard loading
manifold or injection apparatus.
10.7.1.2 Calibration standard tubes may be stored for no longer
than 30 days and should be refrigerated if there is any risk of
chemical interaction or degradation. Audit standards (see section
9.11) are exempt from this criteria and may be stored for the
shelf-life specified on their certificates.
10.8 Keep records for calibration standard tubes to include the
following:
10.8.1 The stock number of any commercial liquid or gas
standards used.
10.8.2 A chromatogram of the most recent blank for each tube
used as a calibration standard together with the associated
analytical conditions and date of cleaning.
10.8.3 Date of standard loading.
10.8.4 List of standard components, approximate masses and
associated confidence levels.
10.8.5 Example analysis of an identical standard with associated
analytical conditions.
10.8.6 A brief description of the method used for standard
preparation.
10.8.7 The standard's expiration date.
10.9 TD/GC/MS using standard tubes to calibrate system
response.
10.9.1 Verify that the TD/GC/MS analytical system meets the
instrument performance criteria given in Section 9.1.
10.9.2 The prepared calibration standard tubes must be analyzed
using the analytical conditions applied to field samples (see
Section 11.0) and must be selected to ensure quantitative transfer
and adequate chromatographic resolution of target compounds,
surrogates, and internal standards in order to enable reliable
identification and quantitation of compounds of interest. The
analytical conditions should also be sufficiently stringent to
prevent buildup of higher boiling, non-target contaminants that may
be collected on the tubes during field monitoring.
10.9.3 Calibration range. Each TD/GC/MS system must be
calibrated at five concentrations that span the monitoring range of
interest before being used for sample analysis. This initial
multi-level calibration determines instrument sensitivity under the
analytical conditions selected and the linearity of GC/MS response
for the target compounds. One of the calibration points must be
within a factor of five of the detection limit for the compounds of
interest.
10.9.4 One of the calibration points from the initial
calibration curve must be at the same concentration as the daily
CCV standard (e.g., the mass collected when sampling air at
typical concentrations).
10.9.5 Calibration frequency. Each GC/MS system must be
recalibrated with a full 5-point calibration curve following
corrective action (e.g., ion source cleaning or repair,
column replacement) or if the instrument fails the daily
calibration acceptance criteria.
10.9.5.1 CCV checks must be carried out on a regular routine
basis as described in Section 9.14.
10.9.5.2 Quantitation ions for the target compounds are shown in
Table 10.1. Use the primary ion unless interferences are present,
in which case you should use a secondary ion.
Table 10.1 - Clean Air Act Volatile Organic
Compounds for Passive Sorbent Sampling
Compound |
CAS No. |
BP
( °C) |
Vapor
pressure
(mmHg) a |
MW
b |
Characteristic
ion(s) |
Primary |
Secondary |
1,1-Dichloroethene |
75-35-4 |
32 |
500 |
96.9 |
61 |
96 |
3-Chloropropene |
107-05-1 |
44.5 |
340 |
76.5 |
76 |
41, 39, 78 |
1,1,2-Trichloro-1,2,2-trifluoroethane-1,1-Dichloroethane |
75-34-3 |
57.0 |
230 |
99 |
63 |
65, 83, 85, 98, 100 |
1,2-Dichloroethane |
107-06-2 |
83.5 |
61.5 |
99 |
62 |
98 |
1,1,1-Trichloroethane |
71-55-6 |
74.1 |
100 |
133.4 |
97 |
99, 61 |
Benzene |
71-43-2 |
80.1 |
76.0 |
78 |
78 |
|
Carbon
tetrachloride |
56-23-5 |
76.7 |
90.0 |
153.8 |
117 |
119 |
1,2-Dichloropropane |
78-87-5 |
97.0 |
42.0 |
113 |
63 |
112 |
Trichloroethene |
79-01-6 |
87.0 |
20.0 |
131.4 |
95 |
97, 130, 132 |
1,1,2-Trichloroethane |
79-00-5 |
114 |
19.0 |
133.4 |
83 |
97, 85 |
Toluene |
108-88-3 |
111 |
22.0 |
92 |
92 |
91 |
Tetrachloroethene |
127-18-4 |
121 |
14.0 |
165.8 |
164 |
129, 131, 166 |
Chlorobenzene |
108-90-7 |
132 |
8.8 |
112.6 |
112 |
77, 114 |
Ethylbenzene |
100-41-4 |
136 |
7.0 |
106 |
91 |
106 |
m,p-Xylene |
108-38-3, 106-42-3 |
138 |
6.5 |
106.2 |
106 |
91 |
Styrene |
100-42-5 |
145 |
6.6 |
104 |
104 |
78 |
o-Xylene |
95-47-6 |
144 |
5.0 |
106.2 |
106 |
91 |
p-Dichlorobenzene |
106-46-7 |
173 |
0.60 |
147 |
146 |
111, 148 |
11.0 Analytical Procedure 11.1 Preparation for Sample Analysis
11.1.1 Each sequence of analyses must be ordered as follows:
11.1.1.1 CCV.
11.1.1.2 A laboratory blank.
11.1.1.3 Field blank.
11.1.1.4 Sample(s).
11.1.1.5 Field blank.
11.1.1.6 CCV after 10 field samples.
11.1.1.7 CCV at the end of the sample batch.
11.2 Pre-desorption System Checks and Procedures
11.2.1 Ensure all sample tubes and field blanks are at ambient
temperature before removing them from the storage container.
11.2.2 If using an automated TD/GC/MS analyzer, remove the
long-term storage caps from the tubes, replace them with
appropriate analytical caps, and load them into the system in the
sequence described in Section 11.1. Alternatively, if using a
manual system, uncap and analyze each tube, one at a time, in the
sequence described in Section 11.1.
11.2.3 The following thermal desorption system integrity checks
and procedures are required before each tube is analyzed.
Note:
Commercial thermal desorbers should implement these steps
automatically.
11.2.3.1 Tube leak test: Each tube must be leak tested as soon
as it is loaded into the carrier gas flow path before analysis to
ensure data integrity.
11.2.3.2 Conduct the leak test at the GC carrier gas pressure,
without heat or gas flow applied. Tubes that fail the leak test
should not be analyzed, but should be resealed and stored intact.
On automated systems, the instrument should continue to leak test
and analyze subsequent tubes after a given tube has failed.
Automated systems must also store and record which tubes in a
sequence have failed the leak test. Information on failed tubes
should be downloaded with the batch of sequence information from
the analytical system.
11.2.3.3 Leak test the sample flow path. Leak check the sample
flow path of the thermal desorber before each analysis without heat
or gas flow applied to the sample tube. Stop the automatic sequence
of tube desorption and GC analysis if any leak is detected in the
main sample flow path. This process may be carried out as a
separate step or as part of Section 11.2.3.2.
11.2.4 Optional Dry Purge
11.2.4.1 Tubes may be dry purged with a flow of pure dry gas
passing into the tube from the sampling end, to remove water vapor
and other very volatile interferents if required.
11.2.5 Internal Standard (IS) Addition
11.2.5.1 Use the internal standard addition function of the
automated thermal desorber (if available) to introduce a precise
aliquot of the internal standard to the sampling end of each tube
after the leak test and shortly before primary (tube)
desorption).
Note:
This step can be combined with dry purging the tube (Section
11.2.4) if required.
11.2.5.2 If the analyzer does not have a facility for automatic
IS addition, gas or liquid internal standard can be manually
introduced to the sampling end of tubes in a flow of carrier gas
using the types of procedure described in Sections 10.3 and 10.4,
respectively.
11.2.6 Pre-purge. Each tube should be purged to vent with
carrier gas flowing in the desorption direction (i.e.,
flowing into the tube from the non-sampling end) to remove oxygen
before heat is applied. This is to prevent analyte and sorbent
oxidation and to prevent deterioration of key analyzer components
such as the GC column and mass spectrometer (if applicable). A
series of schematics illustrating these steps is presented in
Figures 17.2 and 17.3.
11.3 Analytical Procedure 11.3.1 Steps Required for Thermal
Desorption
11.3.1.1 Ensure that the pressure and purity of purge and
carrier gases supplying the TD/GC/MS system, meet manufacturer
specifications and the requirements of this method.
11.3.1.2 Ensure also that the analytical method selected meets
the QC requirements of this method (Section 9) and that all the
analytical parameters are at set point.
11.3.1.3 Conduct predesorption system checks (see Section
11.2).
11.3.1.4 Desorb the sorbent tube under conditions demonstrated
to achieve >95 percent recovery of target compounds (see Section
9.5.2).
Note:
Typical tube desorption conditions range from 280-350 °C for
5-15 minutes with a carrier gas flow of 30-100 mL/min passing
through the tube from the non-sampling end such that analytes are
flushed out of the tube from the sampling end. Desorbed VOCs are
concentrated (refocused) on a secondary, cooled sorbent trap
integrated into the analytical equipment (see Figure 17.4). The
focusing trap is typically maintained at a temperature between −30
and +30 °C during focusing. Selection of hydrophobic sorbents for
focusing and setting a trapping temperature of +25 to 27 °C aid
analysis of humid samples because these settings allow selective
elimination of any residual water from the system, prior to GC/MS
analysis.
Note:
The transfer of analytes from the tube to the focusing trap
during primary (tube) desorption can be carried out splitless or
under controlled split conditions (see Figure 17.4) depending on
the masses of target compounds sampled and the requirements of the
system - sensitivity, required calibration range, column overload
limitations, etc. Instrument controlled sample splits must be
demonstrated by showing the reproducibility using calibration
standards. Field and laboratory blank samples must be analyzed at
the same split as the lowest calibration standard. During secondary
(trap) desorption the focusing trap is heated rapidly (typically at
rates >40 °C/s) with inert (carrier) gas flowing through the
trap (3-100 mL/min) in the reverse direction to that used during
focusing.
11.3.1.5 The split conditions selected for optimum field sample
analysis must also be demonstrated on representative standards.
Note:
Typical trap desorption temperatures are in the range 250-360
°C, with a “hold” time of 1-3 minutes at the highest temperature.
Trap desorption automatically triggers the start of GC analysis.
The trap desorption can also be carried out under splitless
conditions (i.e., with everything desorbed from the trap
being transferred to the analytical column and GC detector) or,
more commonly, under controlled split conditions (see Figure 17.4).
The selected split ratio depends on the masses of target compounds
sampled and the requirements of the system - sensitivity, required
calibration range, column overload limitations, etc. If a split is
selected during both primary (trap) desorption and secondary (trap)
desorption, the overall split ratio is the product of the two. Such
`double' split capability gives optimum flexibility for
accommodating concentrated samples as well as trace-level samples
on the TD/GC/MS analytical system. High resolution capillary
columns and most GC/MS detectors tend to work best with
approximately 20-200 ng per compound per tube to avoid saturation.
The overall split ratio must be adjusted such that, when it is
applied to the sample mass that is expected to be collected during
field monitoring, the amount reaching the column will be attenuated
to fall within this range. As a rule of thumb this means that ∼20
ng samples will require splitless or very low split analysis, ∼2 µg
samples will require a split ratio in the order of ∼50:1 and 200 µg
samples will require a double split method with an overall split
ratio in the order of 2,000:1.
11.3.1.6 Analyzed tubes must be resealed with long-term storage
caps immediately after analysis (manual systems) or after
completion of a sequence (automated systems). This prevents
contamination, minimizing the extent of tube reconditioning
required before subsequent reuse.
11.3.2 GC/MS Analytical Procedure
11.3.2.1 Heat/cool the GC oven to its starting set point.
11.3.2.2 If using a GC/MS system, it can be operated in either
MS-Scan or MS-SIM mode (depending on required sensitivity levels
and the type of mass spectrometer selected). As soon as trap
desorption and transfer of analytes into the GC column triggers the
start of the GC/MS analysis, collect mass spectral data over a
range of masses from 35 to 300 amu. Collect at least 10 data points
per eluting chromatographic peak in order to adequately integrate
and quantify target compounds.
11.3.2.3 Use secondary ion quantitation only when there are
sample matrix interferences with the primary ion. If secondary ion
quantitation is performed, flag the data and document the reasons
for the alternative quantitation procedure.
11.3.2.4 Data reduction is performed by the instruments post
processing program that is automatically accessed after data
acquisition is completed at the end of the GC run. The
concentration of each target compound is calculated using the
previously established response factors for the CCV analyzed in
Section 11.1.1.6.
11.3.2.5 Whenever the thermal desorption - GC/MS analytical
method is changed or major equipment maintenance is performed, you
must conduct a new five-level calibration (see section 10.0).
System calibration remains valid as long as results from subsequent
CCV are within 30 percent of the most recent 5-point calibration
(see section 9.13). Include relevant CCV data in the supporting
information in the data report for each set of samples.
11.3.2.6 Document, flag and explain all sample results that
exceed the calibration range. Report flags and provide
documentation in the analytical results for the affected
sample(s).
12.0 Data Analysis, Calculations, and Reporting 12.1 Recordkeeping
Procedures for Sorbent Tubes
12.1.1 Label sample tubes with a unique identification number as
described in Section 6.3.
12.1.2 Keep records of the tube numbers and sorbent lots used
for each sampling period.
12.1.3 Keep records of sorbent tube packing if tubes are
manually prepared in the laboratory and not supplied commercially.
These records must include the masses and/or bed lengths of
sorbent(s) contained in each tube, the maximum allowable
temperature for that tube and the date each tube was packed. If a
tube is repacked at any stage, record the date of tube repacking
and any other relevant information required in Section 12.1.
12.1.4 Keep records of the conditioning and blanking of tubes.
These records must include, but are not limited to, the unique
identification number and measured background resulting from the
tube conditioning.
12.1.5 Record the location, dates, tube identification and times
associated with each sample collection. Record this information on
a Chain of Custody form that is sent to the analytical
laboratory.
12.1.6 Field sampling personnel must complete and send a Chain
of Custody to the analysis laboratory (see Section 8.6.4 of Method
325A for what information to include and Section 17.0 of this
method for an example form). Duplicate copies of the Chain of
Custody must be included with the sample report and stored with the
field test data archive.
12.1.7 Field sampling personnel must also keep records of the
unit vector wind direction, sigma theta, temperature and barometric
pressure averages for the sampling period. See Section 8.3.4 of
Method 325A.
12.1.8 Laboratory personnel must record the sample receipt date,
and analysis date.
12.1.9 Laboratory personnel must maintain records of the
analytical method and sample results in electronic or hardcopy in
sufficient detail to reconstruct the calibration, sample, and
quality control results from each sampling period.
12.2 Calculations
12.2.1 Complete the calculations in this section to determine
compliance with calibration quality control criteria (see also
Table 17.1).
12.2.1.1 Response factor (RF). Calculate the RF using Equation
12.1:

Where: As
= Peak area for the characteristic ion of the analyte. Ais = Peak
area for the characteristic ion of the internal standard. Ms = Mass
of the analyte. Mis = Mass of the internal standard.
12.2.1.2 Standard deviation of the response factors (SDRF).
Calculate the SDRF using Equation 12.2:

Where:
RFi = RF for each of the calibration compounds. RF = Mean RF for
each compound from the initial calibration. n = Number of
calibration standards.
12.2.1.3 Percent deviation (%DEV). Calculate the %DEV using
Equation 12.3:

Where:
SDRF = Standard deviation. RF = Mean RF for each compound from the
initial calibration.
12.2.1.4 Relative percent difference (RPD). Calculate the RPD
using Equation 12.4:

Where:
R1, R2 = Values that are being compared (
i.e., response
factors in CCV).
12.2.2 Determine the equivalent concentrations of compounds in
atmospheres as follows. Correct target compound concentrations
determined at the sampling site temperature and atmospheric
pressure to standard conditions (25 °C and 760 mm mercury) using
Equation 12.5.

Where:
mmeas = The mass of the compound as measured in the sorbent tube
(µg). t = The exposure time (minutes). tss = The average
temperature during the collection period at the sampling site (K).
UNTP = The method defined diffusive uptake rate (sampling rate)
(mL/min).
Note: Diffusive uptake rates (UNTP) for common VOCs, using
carbon sorbents packed into sorbent tubes of the dimensions
specified in section 6.1, are listed in Table 12.1. Adjust
analytical conditions to keep expected sampled masses within range
(see sections 11.3.1.3 to 11.3.1.5). Best possible method detection
limits are typically in the order of 0.1 ppb for 1,3-butadiene and
0.05 ppb for volatile aromatics such as benzene for 14-day
monitoring. However, actual detection limits will depend upon the
analytical conditions selected.
Table 12.1 - Validated Sorbents and Uptake
Rates (mL/min) for Selected Clean Air Act Compounds
Compound |
Carbopack TM
X a |
Carbograph TM
1
TD |
Carbopack TM
B |
1,1-Dichloroethene |
0.57 ±0.14 |
not available |
not available. |
3-Chloropropene |
0.51 ±0.3 |
not available |
not available. |
1,1-Dichloroethane |
0.57 ±0.1 |
not available |
not available. |
1,2-Dichloroethane |
0.57 ±0.08 |
not available |
not available. |
1,1,1-Trichloroethane |
0.51 ±0.1 |
not available |
not available. |
Benzene |
0.67 ±0.06 |
0.63 ±0.07 b |
0.63 ±0.07 b. |
Carbon
tetrachloride |
0.51 ±0.06 |
not available |
not available. |
1,2-Dichloropropane |
0.52 ±0.1 |
not available |
not available. |
Trichloroethene |
0.5 ±0.05 |
not available |
not available. |
1,1,2-Trichloroethane |
0.49 ±0.13 |
not available |
not available. |
Toluene |
0.52 ±0.14 |
0.56 ±0.06 c |
0.56 ±0.06 c. |
Tetrachloroethene |
0.48 ±0.05 |
not available |
not available. |
Chlorobenzene |
0.51 ±0.06 |
not available |
not available. |
Ethylbenzene |
0.46 ±0.07 |
not available |
0.50 c. |
m,p-Xylene |
0.46 ±0.09 |
0.47 ±0.04 c |
0.47 ±0.04 c. |
Styrene |
0.5 ±0.14 |
not available |
not available. |
o-Xylene |
0.46 ±0.12 |
0.47 ±0.04 c |
0.47 ±0.04 c. |
p-Dichlorobenzene |
0.45 ±0.05 |
not available |
not available. |
13.0 Method Performance
The performance of this procedure for VOC not listed in Table
12.1 is determined using the procedure in Addendum A of this Method
or by one of the following national/international standard methods:
ISO 16017-2:2003(E), ASTM D6196-03 (Reapproved 2009), or BS EN
14662-4:2005 (all incorporated by reference - see § 63.14).
13.1 The valid range for measurement of VOC is approximately 0.5
µg/m 3 to 5 mg/m 3 in air, collected over a 14-day sampling period.
The upper limit of the useful range depends on the split ratio
selected (Section 11.3.1) and the dynamic range of the analytical
system. The lower limit of the useful range depends on the noise
from the analytical instrument detector and on the blank level of
target compounds or interfering compounds on the sorbent tube (see
Section 13.3).
13.2 Diffusive sorbent tubes compatible with passive sampling
and thermal desorption methods have been evaluated at relatively
high atmospheric concentrations (i.e., mid-ppb to ppm) and
published for use in workplace air and industrial/mobile source
emissions (References 15-16, 21-22).
13.3 Best possible detection limits and maximum quantifiable
concentrations of air pollutants range from sub-part-per-trillion
(sub-ppt) for halogenated species such as CCl4 and the freons using
an electron capture detector (ECD), SIM Mode GC/MS, triple quad MS
or GC/TOF MS to sub-ppb for volatile hydrocarbons collected over 72
hours followed by analysis using GC with quadrupole MS operated in
the full SCAN mode.
13.3.1 Actual detection limits for atmospheric monitoring vary
depending on several key factors. These factors are:
• Minimum artifact levels.
• GC detector selection.
• Time of exposure for passive sorbent tubes.
• Selected analytical conditions, particularly column resolution
and split ratio.
14.0 Pollution Prevention
This method involves the use of ambient concentrations of
gaseous compounds that post little or no danger of pollution to the
environment.
15.0 Waste Management
Dispose of expired calibration solutions as hazardous materials.
Exercise standard laboratory environmental practices to minimize
the use and disposal of laboratory solvents.
16.0 References 1. Winberry, W. T. Jr.,
et al.,
Determination of Volatile Organic Compounds in Ambient Air Using
Active Sampling onto Sorbent Tubes: Method TO-17r, Second Edition,
U.S. Environmental Protection Agency, Research Triangle Park, NC
27711, January 1999.
http://www.epa.gov/ttnamti1/airtox.html#compendium 2.
Ciccioli, P., Brancaleoni, E., Cecinato, A., Sparapini, R., and
Frattoni, M., “Identification and Determination of Biogenic and
Anthropogenic VOCs in Forest Areas of Northern and Southern Europe
and a Remote Site of the Himalaya Region by High-resolution GC-MS,”
J. of Chrom., 643, pp 55-69, 1993. 3. McClenny, W.A., K.D. Oliver,
H.H. Jacumin, Jr., E.H. Daughtrey, Jr., D.A. Whitaker. 2005. 24 h
diffusive sampling of toxic VOCs in air onto Carbopack TM X solid
adsorbent followed by thermal desorption/GC/MS analysis -
laboratory studies. J. Environ. Monit. 7:248-256. 4. Markes
International (
www.markes.com/publications): Thermal
desorption Technical Support Note 2: Prediction of uptake rates for
diffusive tubes. 5. Ciccioli, P., Brancaleoni, E., Cecinato, A.,
DiPalo, C., Brachetti, A., and Liberti, A., “GC Evaluation of the
Organic Components Present in the Atmosphere at Trace Levels with
the Aid of CarbopackTM B for Preconcentration of the Sample,” J. of
Chrom., 351, pp 433-449, 1986. 6. Broadway, G. M., and Trewern, T.,
“Design Considerations for the Optimization of a Packed Thermal
Desorption Cold Trap for Capillary Gas Chromatography,” Proc. 13th
Int'l Symposium on Capil. Chrom., Baltimore, MD, pp 310-320, 1991.
7. Broadway, G. M., “An Automated System for use Without Liquid
Cryogen for the Determination of VOC's in Ambient Air,” Proc. 14th
Int'l. Symposium on Capil. Chrom., Baltimore, MD, 1992. 8. Gibitch,
J., Ogle, L., and Radenheimer, P., “Analysis of Ozone Precursor
Compounds in Houston, Texas Using Automated Continuous GCs,” in
Proceedings of the Air and Waste Management Association Conference:
Measurement of Toxic and Related Air Pollutants, Air and Waste
Management Association, Pittsburgh, PA, May 1995. 9.
Vandendriessche, S., and Griepink, B., “The Certification of
Benzene, Toluene and m-Xylene Sorbed on Tenax® TA in Tubes,”
CRM-112 CEC, BCR, EUR12308 EN, 1989. 10. MDHS 2 (Acrylonitrile in
Air), “Laboratory Method Using Porous Polymer Adsorption Tubes, and
Thermal Desorption with Gas Chromatographic Analysis,” Methods for
the Determination of Hazardous Substances (MDHS), UK Health and
Safety Executive, Sheffield, UK. 11. MDHS 22 (Benzene in Air),
“Laboratory Method Using Porous Polymer Adsorbent Tubes, Thermal
Desorption and Gas Chromatography,” Method for the Determination of
Hazardous Substances (MDHS), UK Health and Safety Executive,
Sheffield, UK. 12. MDHS 23 (Glycol Ether and Glycol Acetate Vapors
in Air), “Laboratory Method Using Tenax® Sorbent Tubes, Thermal
Desorption and Gas Chromatography,” Method for the Determination of
Hazardous Substances (MDHS), UK Health and Safety Executive,
Sheffield, UK. 13. MDHS 40 (Toluene in air), “Laboratory Method
Using Pumped Porous Polymer Adsorbent Tubes, Thermal Desorption and
Gas Chromatography,” Method for the Determination of Hazardous
Substances (MDHS), UK Health and Safety Executive, Sheffield, UK.
14. MDHS 60 (Mixed Hydrocarbons (C to C) in Air), “Laboratory
Method Using Pumped Porous Polymer 3 10 and Carbon Sorbent Tubes,
Thermal Desorption and Gas Chromatography,” Method for the
Determination of Hazardous Substances (MDHS), UK Health and Safety
Executive, Sheffield, UK. 15. Price, J. A., and Saunders, K. J.,
“Determination of Airborne Methyl tert-Butyl Ether in Gasoline
Atmospheres,” Analyst, Vol. 109, pp. 829-834, July 1984. 16. Coker,
D. T., van den Hoed, N., Saunders, K. J., and Tindle, P. E., “A
Monitoring Method for Gasoline Vapour Giving Detailed Composition,”
Ann. Occup, Hyg., Vol 33, No. 11, pp 15-26, 1989. 17. DFG,
“Analytische Methoden zur prufing gesundheitsschadlicher
Arbeistsstoffe,” Deutsche Forschungsgemeinschaft, Verlag Chemie,
Weinheim FRG, 1985. 18. NNI, “Methods in NVN Series
(Luchtkwaliteit; Werkplekatmasfeer),” Nederlands Normailsatie -
Institut, Delft, The Netherlands, 1986-88. 19. “Sampling by Solid
Adsorption Techniques,” Standards Association of Australia Organic
Vapours, Australian Standard 2976, 1987. 20. Woolfenden, E. A.,
“Monitoring VOCs in Air Using Pumped Sampling onto Sorbent Tubes
Followed by Thermal Desorption-capillary GC Analysis: Summary of
Reported Data and Practical Guidelines for Successful Application,”
J. Air & Waste Manage. Assoc., Vol. 47, 1997, pp. 20-36. 21.
Validation Guidelines for Air Sampling Methods Utilizing
Chromatographic Analysis, OSHA T-005, Version 3.0, May 2010,
http://www.osha.gov/dts/sltc/methods/chromguide/chromguide.pdf.
22. ASTM D4597-10, Standard Practice for Sampling Workplace
Atmospheres to collect Gases or Vapors with Solid Sorbent Diffusive
Samplers. 23. Martin,
http://www.hsl.gov.uk/media/1619/issue14.pdf. 24. BS EN
14662-4:2005, Ambient air quality - Standard method for the
measurement of benzene concentrations - Part 4: Diffusive sampling
followed by thermal desorption and gas chromatography. 25. ISO
16017-2:2003(E): Indoor, ambient and workplace air - Sampling and
analysis of volatile organic compounds by sorbent tube/thermal
desorption/capillary gas chromatography - Part 2: Diffusive
sampling. 17.0 Tables, Diagrams, Flowcharts and Validation Data
>
Table 17.1 - Summary of GC/MS Analysis
Quality Control Procedures
Parameter |
Frequency |
Acceptance criteria |
Corrective action |
Bromofluorobenzene
Instrument Tune Performance Check |
Daily a prior to
sample analysis |
Evaluation criteria presented
in Section 9.5 and Table 9.2 |
(1) Retune and or
(2) Perform Maintenance. |
Five point
calibration bracketing the expected sample concentration |
Following any major change,
repair or maintenance or if daily CCV does not meet method
requirements. Recalibration not to exceed three months |
(1) Percent Deviation (%DEV)
of response factors ±30%
(2) Relative Retention Times (RRTs) for target peaks ±0.06 units
from mean RRT |
(1) Repeat calibration sample
analysis.
(2) Repeat linearity check.
(3) Prepare new calibration standards as necessary and repeat
analysis. |
Calibration
Verification (CCV Second source calibration verification
check) |
Following the calibration
curve |
The response factor ±30% DEV
from calibration curve average response factor |
(1) Repeat calibration
check.
(2) Repeat calibration curve. |
Laboratory Blank
Analysis |
Daily a following
bromofluoro benzene and calibration check; prior to sample
analysis |
(1) ≤0.2 ppbv per analyte or
≤3 times the LOD, whichever is greater
(2) Internal Standard (IS) area response ±40% and IS Retention Time
(RT) ±0.33 min. of most recent calibration check |
(1) Repeat analysis with new
blank tube.
(2) Check system for leaks, contamination.
(3) Analyze additional blank. |
Blank Sorbent Tube
Certification |
One tube analyzed for each
batch of tubes cleaned or 10 percent of tubes whichever is
greater |
<0.2 ppbv per VOC targeted
compound or 3 times the LOD, whichever is greater |
Re-clean all tubes in batch
and reanalyze. |
Samples - Internal
Standards |
All samples |
IS area response ±40% and IS
RT ±0.33 min. of most recent calibration validation |
Flag Data for possible
invalidation. |
Field Blanks |
Two per sampling period |
No greater than one-third of
the measured target analyte or compliance limit |
Flag Data for possible
invalidation due to high blank bias. |
ADDENDUM A to Method 325B - Method 325 Performance
Evaluation
A.1 Scope and Application
A.1.1 To be measured by Methods 325A and 325B, each new target
volatile organic compound (VOC) or sorbent that is not listed in
Table 12.1 must be evaluated by exposing the selected sorbent tube
to a known concentration of the target compound(s) in an exposure
chamber following the procedure in this Addendum or by following
the procedures in the national/international standard methods: ISO
16017-2:2003(E), ASTM D6196-03 (Reapproved 2009), or BS EN
14662-4:2005 (all incorporated by reference - see § 63.14), or
reported in peer-reviewed open literature.
A.1.2 You must determine the uptake rate and the relative
standard deviation compared to the theoretical concentration of
volatile material in the exposure chamber for each of the tests
required in this method. If data that meet the requirement of this
Addendum are available in the peer reviewed open literature for
VOCs of interest collected on your passive sorbent tube
configuration, then such data may be submitted in lieu of the
testing required in this Addendum.
A.1.3 You must expose sorbent tubes in a test chamber to parts
per trillion by volume (pptv) and low parts per billion by volume
(ppbv) concentrations of VOCs in humid atmospheres to determine the
sorbent tube uptake rate and to confirm compound capture and
recovery.
A.2 Summary of Method Note:
The technique described here is one approach for determining
uptake rates for new sorbent/sorbate pairs. It is equally valid to
follow the techniques described in any one of the following
national/international standards methods: ISO 16017-2:2003(E), ASTM
D6196-03 (Reapproved 2009), or BS EN 14662-4:2005 (all incorporated
by reference - see § 63.14).
A.2.1 Known concentrations of VOC are metered into an exposure
chamber containing sorbent tubes filled with media selected to
capture the volatile organic compounds of interest (see Figure A.1
and A.2 for an example of the exposure chamber and sorbent tube
retaining rack). VOC are diluted with humid air and the chamber is
allowed to equilibrate for 6 hours. Clean passive sampling devices
are placed into the chamber and exposed for a measured period of
time. The passive uptake rate of the passive sampling devices is
determined using the standard and dilution gas flow rates. Chamber
concentrations are confirmed with whole gas sample collection and
analysis or direct interface volatile organic compound measurement
methods.
A.2.2 An exposure chamber and known gas concentrations must be
used to challenge and evaluate the collection and recovery of
target compounds from the sorbent and tube selected to perform
passive measurements of VOC in atmospheres.
A.3 Definitions
A.3.1 cc is cubic centimeter.
A.3.2 ECD is electron capture detector.
A.3.3 FID is flame ionization detector.
A.3.4 LED is light-emitting diode.
A.3.5 MFC is mass flow controller.
A.3.6 MFM is mass flow meter.
A.3.7 min is minute.
A.3.8 ppbv is parts per billion by volume.
A.3.9 ppmv is parts per million by volume.
A.3.10 PSD is passive sampling device.
A.3.11 psig is pounds per square inch gauge.
A.3.12 RH is relative humidity.
A.3.13 VOC is volatile organic compound.
A.4 Interferences
A.4.1 VOC contaminants in water can contribute interference or
bias results high. Use only distilled, organic-free water for
dilution gas humidification.
A.4.2 Solvents and other VOC-containing liquids can contaminate
the exposure chamber. Store and use solvents and other
VOC-containing liquids in the exhaust hood when exposure
experiments are in progress to prevent the possibility of
contamination of VOCs into the chamber through the chamber's
exhaust vent.
Note:
Whenever possible, passive sorbent evaluation should be
performed in a VOC free laboratory.
A.4.3 PSDs should be handled by personnel wearing only clean,
white cotton or powder free nitrile gloves to prevent contamination
of the PSDs with oils from the hands.
A.4.4 This performance evaluation procedure is applicable to
only volatile materials that can be measured accurately with direct
interface gas chromatography or whole gas sample collection,
concentration and analysis. Alternative methods to confirm the
concentration of volatile materials in exposure chambers are
subject to Administrator approval.
A.5 Safety
A.5.1 This procedure does not address all of the safety concerns
associated with its use. It is the responsibility of the user of
this standard to establish appropriate field and laboratory safety
and health practices and determine the applicability of regulatory
limitations prior to use.
A.5.2 Laboratory analysts must exercise appropriate care in
working with high-pressure gas cylinders.
A.6 Equipment and Supplies
A.6.1 You must use an exposure chamber of sufficient size to
simultaneously expose a minimum of eight sorbent tubes.
A.6.2 Your exposure chamber must not contain VOC that interfere
with the compound under evaluation. Chambers made of glass and/or
stainless steel have been used successfully for measurement of
known concentration of selected VOC compounds.
A.6.3 The following equipment and supplies are needed:
• Clean, white cotton or nitrile gloves;
• Conditioned passive sampling device tubes and diffusion caps;
and
• NIST traceable high resolution digital gas mass flow meters
(MFMs) or flow controllers (MFCs).
A.7 Reagents and Standards
A.7.1 You must generate an exposure gas that contains between 35
and 75 percent relative humidity and a concentration of target
compound(s) within 2 to 5 times the concentration to be measured in
the field.
A.7.2 Target gas concentrations must be generated with certified
gas standards and diluted with humid clean air. Dilution to reach
the desired concentration must be done with zero grade air or
better.
A.7.3 The following reagents and standards are needed:
• Distilled water for the humidification;
• VOC standards mixtures in high-pressure cylinder certified by
the supplier (Note: The accuracy of the certified standards has a
direct bearing on the accuracy of the measurement results. Typical
vendor accuracy is ±5 percent accuracy but some VOC may only be
available at lower accuracy (e.g., acrolein at 10 percent));
and
• Purified dilution air containing less than 0.2 ppbv of the
target VOC.
A.8 Sample Collection, Preservation and Storage
A.8.1 You must use certified gas standards diluted with humid
air. Generate humidified air by adding distilled organic free water
to purified or zero grade air. Humidification may be accomplished
by quantitative addition of water to the air dilution gas stream in
a heated chamber or by passing purified air through a humidifying
bubbler. You must control the relative humidity in the test gas
throughout the period of passive sampler exposure.
Note:
The RH in the exposure chamber is directly proportional to the
fraction of the purified air that passes through the water in the
bubbler before entering the exposure chamber. Achieving uniform
humidification in the proper range is a trial-and-error process
with a humidifying bubbler. You may need to heat the bubbler to
achieve sufficient humidity. An equilibration period of
approximately 15 minutes is required following each adjustment of
the air flow through the humidifier. Several adjustments or
equilibration cycles may be required to achieve the desired RH
level.
Note:
You will need to determine both the dilution rate and the
humidification rate for your design of the exposure chamber by
trial and error before performing method evaluation tests.
A.8.2 Prepare and condition sorbent tubes following the
procedures in Method 325B Section 7.0.
A.8.3 You must verify that the exposure chamber does not
leak.
A.8.4 You must complete two evaluation tests using a minimum of
eight passive sampling tubes in each test with less than 5-percent
depletion of test analyte by the samplers.
A.8.4.1 Perform at least one evaluation at two to five times the
estimated analytical detection limit or less.
A.8.4.2 Perform second evaluation at a concentration equivalent
to the middle of the analysis calibration range.
A.8.5 You must evaluate the samplers in the test chamber
operating between 35 percent and 75 percent RH, and at 25 ±5 °C.
Allow the exposure chamber to equilibrate for 6 hours before
starting an evaluation.
A.8.6 The flow rate through the chamber must be ≤0.5 meter per
second face velocity across the sampler face.
A.8.7 Place clean, ready to use sorbent tubes into the exposure
chamber for predetermined amounts of time to evaluate collection
and recovery from the tubes. The exposure time depends on the
concentration of volatile test material in the chamber and the
detection limit required for the sorbent tube sampling application.
Exposure time should match sample collection time. The sorbent tube
exposure chamber time may not be less than 24 hours and should not
be longer than 2 weeks.
A.8.7.1 To start the exposure, place the clean PSDs equipped
with diffusion caps on the tube inlet into a retaining rack.
A.8.7.2 Place the entire retaining rack inside the exposure
chamber with the diffusive sampling end of the tubes facing into
the chamber flow. Seal the chamber and record the exposure start
time, chamber RH, chamber temperature, PSD types and numbers,
orientation of PSDs, and volatile material mixture composition (see
Figure A.2).
A.8.7.3 Diluted, humidified target gas must be continuously fed
into the exposure chamber during cartridge exposure. Measure the
flow rate of target compound standard gas and dilution air to an
accuracy of 5 percent.
A.8.7.4 Record the time, temperature, and RH at the beginning,
middle, and end of the exposure time.
A.8.7.5 At the end of the exposure time, remove the PSDs from
the exposure chamber. Record the exposure end time, chamber RH, and
temperature.

A.9 Quality
Control
A.9.1 Monitor and record the exposure chamber temperature and RH
during PSD exposures.
A.9.2 Measure the flow rates of standards and purified humified
air immediately following PSD exposures.
A.10 Calibration and Standardization
A.10.1 Follow the procedures described in Method 325B Section
10.0 for calibration.
A.10.2 Verify chamber concentration by direct injection into a
gas chromatograph calibrated for the target compound(s) or by
collection of an integrated SUMMA canister followed by analysis
using a preconcentration gas chromatographic method such as EPA
Compendium Method TO-15, Determination of VOCs in Air Collected in
Specially-Prepared Canisters and Analyzed By GC/MS.
A.10.2.1 To use direct injection gas chromatography to verify
the exposure chamber concentration, follow the procedures in Method
18 of 40 CFR part 60, Appendix A-6. The method ASTM D6420-99
(Reapproved 2010) (incorporated by reference - see § 63.14) is an
acceptable alternative to EPA Method 18 of 40 CFR part 60).
Note:
Direct injection gas chromatography may not be sufficiently
sensitive for all compounds. Therefore, the whole gas
preconcentration sample and analysis method may be required to
measure at low concentrations.
A.10.2.2 To verify exposure chamber concentrations using SUMMA
canisters, prepare clean canister(s) and measure the concentration
of VOC collected in an integrated SUMMA canister over the period
used for the evaluation (minimum 24 hours). Analyze the TO-15
canister sample following EPA Compendium Method TO-15.
A.10.2.3 Compare the theoretical concentration of volatile
material added to the test chamber to the measured concentration to
confirm the chamber operation. Theoretical concentration must agree
with the measured concentration within 30 percent.
A.11 Analysis Procedure
Analyze the sorbent tubes following the procedures described in
Section 11.0 of Method 325B.
A.12 Recordkeeping Procedures for Sorbent Tube Evaluation
Keep records for the sorbent tube evaluation to include at a
minimum the following information:
A.12.1 Sorbent tube description and specifications.
A.12.2 Sorbent material description and specifications.
A.12.3 Volatile analytes used in the sampler test.
A.12.4 Chamber conditions including flow rate, temperature, and
relative humidity.
A.12.5 Relative standard deviation of the sampler results at the
conditions tested.
A.12.6 95 percent confidence limit on the sampler overall
accuracy.
A.12.7 The relative accuracy of the sorbent tube results
compared to the direct chamber measurement by direct gas
chromatography or SUMMA canister analysis.
A.13 Method Performance
A.13.1 Sorbent tube performance is acceptable if the relative
accuracy of the passive sorbent sampler agrees with the active
measurement method by ±10 percent at the 95 percent confidence
limit and the uptake ratio is equal to greater than 0.5 mL/min (1
ng/ppm-min).
Note:
For example, there is a maximum deviation comparing Perkin-Elmer
passive type sorbent tubes packed with Carbopack TM X of 1.3 to 10
percent compared to active sampling using the following uptake
rates.
|
1,3-butadiene
uptake rate
mL/min |
Estimated
detection limit
(2 week) |
Benzene
uptake rates
mL/min |
Estimated
detection limit
(2 week) |
Carbopack
TM X (2 week) |
0.61 ±0.11 a |
0.1 ppbv |
0.67 a |
0.05 ppbv |
A13.2 Data Analysis and Calculations for Method Evaluation
A.13.2.1 Calculate the theoretical concentration of VOC
standards using Equation A.1.

Where: Cf
= The final concentration of standard in the exposure chamber
(ppbv). FRi = The flow rate of the target compound I (mL/min). FRt
= The flow rate of all target compounds from separate if multiple
cylinders are used (mL/min). FRa = The flow rate of dilution air
plus moisture (mL/min). Cs = The concentration of target compound
in the standard cylinder (parts per million by volume).
A.13.2.3 Determine the uptake rate of the target gas being
evaluated using Equation A.2.

Where: MX
= The mass of analyte measured on the sampling tube (ηg). Ce = The
theoretical exposure chamber concentration (ηg/mL). Tt = The
exposure time (minutes).
A.13.2.4 Estimate the variance (relative standard deviation
(RSD)) of the inter-sampler results at each condition tested using
Equation A.3. RSD for the sampler is estimated by pooling the
variance estimates from each test run.

Where: Xi
= The measured mass of analyte found on sorbent tube
i. Xi =
The mean value of all Xi. n = The number of measurements of the
analyte.
A.13.2.4 Determine the percent relative standard deviation of
the inter-sampler results using Equation A.4.
A.13.2.5 Determine the 95 percent confidence interval for the
sampler results using Equation A.5. The confidence interval is
determined based on the number of test runs performed to evaluate
the sorbent tube and sorbent combination. For the minimum test
requirement of eight samplers tested at two concentrations, the
number of tests is 16 and the degrees of freedom are 15.

Where:
Δ95% = 95 percent confidence interval. %RSD = percent relative
standard deviation. t0.95 = The Students t statistic for f degrees
of freedom at 95 percent confidence. f = The number of degrees of
freedom. n = Number of samples.
A.13.2.6 Determine the relative accuracy of the sorbent tube
combination compared to the active sampling results using Equation
A.6.

Where: RA
= Relative accuracy. Xi = The mean value of all Xi. Xi = The
average concentration of analyte measured by the active measurement
method. Δ95% = 95 percent confidence interval. A.14 Pollution
Prevention
This method involves the use of ambient concentrations of
gaseous compounds that post little or no pollution to the
environment.
A.15 Waste Management
Expired calibration solutions should be disposed of as hazardous
materials.
A.16 References
1. ISO TC 146/SC 02 N 361 Workplace atmospheres - Protocol for
evaluating the performance of diffusive samplers.
Method 326 - Method for Determination of Isocyanates in Stationary
Source Emissions 1.0
Scope and Application
This method is applicable to the collection and analysis of
isocyanate compounds from the emissions associated with
manufacturing processes. This method is not inclusive with respect
to specifications (e.g., equipment and supplies) and
sampling procedures essential to its performance. Some material is
incorporated by reference from other EPA methods. Therefore, to
obtain reliable results, persons using this method should have a
thorough knowledge of at least Method 1, Method 2, Method 3, and
Method 5 found in Appendices A-1, A-2, and A-3 in Part 60 of this
title.
1.1 Analytes. This method is designed to determine the mass
emission of isocyanates being emitted from manufacturing processes.
The following is a table (Table 1-1) of the isocyanates and the
manufacturing process at which the method has been evaluated:
Compound's name |
CAS No. |
Detection limit (ng/m
3) a |
Manufacturing process |
2,4-Toluene
Diisocyanate (TDI) |
584-84-9 |
106 |
Flexible Foam Production. |
1,6-Hexamethylene
Diisocyanate (HDI) |
822-06-0 |
396 |
Paint Spray Booth. |
Methylene Diphenyl
Diisocyanate (MDI) |
101-68-8 |
112 |
Pressed Board Production. |
Methyl Isocyanate
(MI) |
624-83-0 |
228 |
Not used in production. |
1.2 Applicability. Method 326 is a method designed for
determining compliance with National Emission Standards for
Hazardous Air Pollutants (NESHAP). Method 326 may also be specified
by New Source Performance Standards (NSPS), State Implementation
Plans (SIPs), and operating permits that require measurement of
isocyanates in stationary source emissions, to determine compliance
with an applicable emission standard or limit.
1.3 Data Quality Objectives (DQO). The principal objective is to
ensure the accuracy of the data at the actual emissions levels and
in the actual emissions matrix encountered. To meet this objective,
method performance tests are required and NIST-traceable
calibration standards must be used.
2.0 Summary of Method
2.1 Gaseous and/or aerosol isocyanates are withdrawn from an
emission source at an isokinetic sampling rate and are collected in
a multicomponent sampling train. The primary components of the
train include a heated probe, three impingers containing
derivatizing reagent in toluene, an empty impinger, an impinger
containing charcoal, and an impinger containing silica gel.
2.2 The liquid impinger contents are recovered, concentrated to
dryness under vacuum, brought to volume with acetonitrile (ACN) and
analyzed with a high pressure liquid chromatograph (HPLC).
3.0 Definitions [Reserved] 4.0 Interferences
4.1 The greatest potential for interference comes from an
impurity in the derivatizing reagent, 1-(2-pyridyl)piperazine
(1,2-PP). This compound may interfere with the resolution of MI
from the peak attributed to unreacted 1,2-PP.
4.2 Other interferences that could result in positive or
negative bias are (1) alcohols that could compete with the 1,2-PP
for reaction with an isocyanate and (2) other compounds that may
co-elute with one or more of the derivatized isocyanates.
4.3 Method interferences may be caused by contaminants in
solvents, reagents, glassware, and other sample processing
hardware. All these materials must be routinely shown to be free
from interferences under conditions of the analysis by preparing
and analyzing laboratory method (or reagent) blanks.
4.3.1 Glassware must be cleaned thoroughly before using. The
glassware should be washed with laboratory detergent in hot water
followed by rinsing with tap water and distilled water. The
glassware may be dried by baking in a glassware oven at 400 °C for
at least one hour. After the glassware has cooled, it should be
rinsed three times with methylene chloride and three times with
acetonitrile. Volumetric glassware should not be heated to 400 °C.
Instead, after washing and rinsing, volumetric glassware may be
rinsed with acetonitrile followed by methylene chloride and allowed
to dry in air.
4.3.2 The use of high purity reagents and solvents helps to
reduce interference problems in sample analysis.
5.0 Safety
5.1 Organizations performing this method are responsible for
maintaining a current awareness file of Occupational Safety and
Health Administration (OSHA) regulations regarding safe handling of
the chemicals specified in this method. A reference file of
material safety data sheets should also be made available to all
personnel involved in performing the method. Additional references
to laboratory safety are available.
6.0 Equipment and Supplies
6.1 Sample Collection. A schematic of the sampling train used in
this method is shown in Figure 207-1. This sampling train
configuration is adapted from Method 5 procedures, and, as such,
most of the required equipment is identical to that used in Method
5 determinations. The only new component required is a
condenser.
6.1.1 Probe Nozzle. Borosilicate or quartz glass; constructed
and calibrated according to Method 5, sections 6.1.1.1 and 10.1,
and coupled to the probe liner using a Teflon union; a stainless
steel nut is recommended for this union. When the stack temperature
exceeds 210 °C (410 °F), a one-piece glass nozzle/liner assembly
must be used.
6.1.2 Probe Liner. Same as Method 5, section 6.1.1.2, except
metal liners shall not be used. Water-cooling of the stainless
steel sheath is recommended at temperatures exceeding 500 °C (932
°F). Teflon may be used in limited applications where the minimum
stack temperature exceeds 120 °C (250 °F) but never exceeds the
temperature where Teflon is estimated to become unstable
[approximately 210 °C (410 °F)].
6.1.3 Pitot Tube, Differential Pressure Gauge, Filter Heating
System, Metering System, Barometer, Gas Density Determination
Equipment. Same as Method 5, sections 6.1.1.3, 6.1.1.4, 6.1.1.6,
6.1.1.9, 6.1.2, and 6.1.3.
6.1.4 Impinger Train. Glass impingers are connected in series
with leak-free ground-glass joints following immediately after the
heated probe. The first impinger shall be of the Greenburg-Smith
design with the standard tip. The remaining five impingers shall be
of the modified Greenburg-Smith design, modified by replacing the
tip with a 1.3-cm ( 1/2-in.) I.D. glass tube extending about 1.3 cm
( 1/2 in.) from the bottom of the outer cylinder. A water-jacketed
condenser is placed between the outlet of the first impinger and
the inlet to the second impinger to reduce the evaporation of
toluene from the first impinger.
6.1.5 Moisture Measurement. For the purpose of calculating
volumetric flow rate and isokinetic sampling, you must also collect
either Method 4 in Appendix A-3 to this part or other moisture
measurement methods approved by the Administrator concurrent with
each Method 326 test run.
6.2 Sample Recovery
6.2.1 Probe and Nozzle Brushes; Polytetrafluoroethylene (PTFE)
bristle brushes with stainless steel wire or PTFE handles are
required. The probe brush shall have extensions constructed of
stainless steel, PTFE, or inert material at least as long as the
probe. The brushes shall be properly sized and shaped to brush out
the probe liner and the probe nozzle.
6.2.2 Wash Bottles. Three. PTFE or glass wash bottles are
recommended; polyethylene wash bottles must not be used because
organic contaminants may be extracted by exposure to organic
solvents used for sample recovery.
6.2.3 Glass Sample Storage Containers. Chemically resistant,
borosilicate amber glass bottles, 500-mL or 1,000-mL. Bottles
should be tinted to prevent the action of light on the sample.
Screw-cap liners shall be either PTFE or constructed to be
leak-free and resistant to chemical attack by organic recovery
solvents. Narrow-mouth glass bottles have been found to leak less
frequently.
6.2.4 Graduated Cylinder. To measure impinger contents to the
nearest 1 ml or 1 g. Graduated cylinders shall have subdivisions
not >2 mL.
6.2.5 Plastic Storage Containers. Screw-cap polypropylene or
polyethylene containers to store silica gel and charcoal.
6.2.6 Funnel and Rubber Policeman. To aid in transfer of silica
gel or charcoal to container (not necessary if silica gel is
weighed in field).
6.2.7 Funnels. Glass, to aid in sample recovery.
6.3 Sample Preparation and Analysis.
The following items are required for sample analysis.
6.3.1 Rotary Evaporator. Buchii Model EL-130 or equivalent.
6.3.2 1000 ml Round Bottom Flask for use with a rotary
evaporator.
6.3.3 Separatory Funnel. 500-ml or larger, with PTFE
stopcock.
6.3.4 Glass Funnel. Short-stemmed or equivalent.
6.3.5 Vials. 15-ml capacity with PTFE lined caps.
6.3.6 Class A Volumetric Flasks. 10-ml for bringing samples to
volume after concentration.
6.3.7 Filter Paper. Qualitative grade or equivalent.
6.3.8 Buchner Funnel. Porcelain with 100 mm ID or
equivalent.
6.3.9 Erlenmeyer Flask. 500-ml with side arm and vacuum
source.
6.3.10 HPLC with at least a binary pumping system capable of a
programmed gradient.
6.3.11 Column Systems Column systems used to measure isocyanates
must be capable of achieving separation of the target compounds
from the nearest eluting compound or interferents with no more than
10 percent peak overlap.
6.3.12 Detector. UV detector at 254 nm. A fluorescence detector
(FD) with an excitation of 240 nm and an emission at 370 nm may be
also used to allow the detection of low concentrations of
isocyanates in samples.
6.3.13 Data system for measuring peak areas and retention
times.
7.0 Reagents and Standards
7.1 Sample Collection Reagents.
7.1.1 Charcoal. Activated, 6-16 mesh. Used to absorb toluene
vapors and prevent them from entering the metering device. Use once
with each train and discard.
7.1.2 Silica Gel and Crushed Ice. Same as Method 5, sections
7.1.2 and 7.1.4 respectively
7.1.3 Impinger Solution. The impinger solution is prepared by
mixing a known amount of 1-(2-pyridyl) piperazine (purity 99.5+%)
in toluene (HPLC grade or equivalent). The actual concentration of
1,2-PP should be approximately four times the amount needed to
ensure that the capacity of the derivatizing solution is not
exceeded. This amount shall be calculated from the stoichiometric
relationship between 1,2-PP and the isocyanate of interest and
preliminary information about the concentration of the isocyanate
in the stack emissions. A concentration of 130 µg/ml of 1,2-PP in
toluene can be used as a reference point. This solution shall be
prepared, stored in a refrigerated area away from light, and used
within ten days of preparation.
7.2 Sample Recovery Reagents.
7.2.1 Toluene. HPLC grade is required for sample recovery and
cleanup (see Note to 7.2.2 below).
7.2.2 Acetonitrile. HPLC grade is required for sample recovery
and cleanup. Note: Organic solvents stored in metal containers may
have a high residue blank and should not be used. Sometimes
suppliers transfer solvents from metal to glass bottles; thus
blanks shall be run before field use and only solvents with a low
blank value should be used.
7.3 Analysis Reagents. Reagent grade chemicals should be used in
all tests. All reagents shall conform to the specifications of the
Committee on Analytical Reagents of the American Chemical Society,
where such specifications are available.
7.3.1 Toluene, C6H5CH3. HPLC Grade or equivalent.
7.3.2 Acetonitrile, CH3CN (ACN). HPLC Grade or equivalent.
7.3.3 Methylene Chloride, CH2Cl2. HPLC Grade or equivalent.
7.3.4 Hexane, C6H14. HPLC Grade or equivalent.
7.3.5 Water, H2O. HPLC Grade or equivalent.
7.3.6 Ammonium Acetate, CH3CO2NH4.
7.3.7 Acetic Acid (glacial), CH3CO2H.
7.3.8 1-(2-Pyridyl)piperazine, (1,2-PP), ≥99.5% or
equivalent.
7.3.9 Absorption Solution. Prepare a solution of
1-(2-pyridyl)piperazine in toluene at a concentration of 40 mg/300
ml. This solution is used for method blanks and method spikes.
7.3.10 Ammonium Acetate Buffer Solution (AAB). Prepare a
solution of ammonium acetate in water at a concentration of 0.1 M
by transferring 7.705 g of ammonium acetate to a 1,000 ml
volumetric flask and diluting to volume with HPLC Grade water.
Adjust pH to 6.2 with glacial acetic acid.
8.0 Sample Collection, Storage and Transport Note:
Because of the complexity of this method, field personnel should
be trained in and experienced with the test procedures in order to
obtain reliable results.
8.1 Sampling
8.1.1 Preliminary Field Determinations. Same as Method 5,
section 8.2.
8.1.2 Preparation of Sampling Train. Follow the general
procedure given in Method 5, section 8.3.1, except for the
following variations: Place 300 ml of the impinger absorbing
solution in the first impinger and 200 ml each in the second and
third impingers. The fourth impinger shall remain empty. The fifth
and sixth impingers shall have 400 g of charcoal and 200-300 g of
silica gel, respectively. Alternatively, the charcoal and silica
gel may be combined in the fifth impinger. Set-up the train as in
Figure 326-1. During assembly, do not use any silicone grease on
ground-glass joints.
Note:
During preparation and assembly of the sampling train, keep all
openings where contamination can occur covered with PTFE film or
aluminum foil until just before assembly or until sampling is about
to begin.
8.1.3 Leak-Check Procedures. Follow the leak-check procedures
given in Method 5, sections 8.4.2 (Pretest Leak-Check), 8.4.3
(Leak-Checks During the Sample Run), and 8.4.4 (Post-Test
Leak-Check), with the exception that the pre-test leak-check is
mandatory
8.1.4 Sampling Train Operation. Follow the general procedures
given in Method 5, section 8.5. Turn on the condenser coil coolant
recirculating pump and monitor the gas entry temperature. Ensure
proper gas entry temperature before proceeding and again before any
sampling is initiated. It is important that the gas entry
temperature not exceed 50 °C (122 °F), thus reducing the loss of
toluene from the first impinger. For each run, record the data
required on a data sheet such as the one shown in Method 5, Figure
5-3.
8.2 Sample Recovery. Allow the probe to cool. When the probe can
be handled safely, wipe off all external particulate matter near
the tip of the probe nozzle and place a cap over the tip to prevent
losing or gaining particulate matter. Do not cap the probe tip
tightly while the sampling train is cooling down because this will
create a vacuum in the train. Before moving the sample train to the
cleanup site, remove the probe from the sample train and cap the
opening to the probe, being careful not to lose any condensate that
might be present. Cap the impingers and transfer the probe and the
impinger/condenser assembly to the cleanup area. This area should
be clean and protected from the weather to reduce sample
contamination or loss. Inspect the train prior to and during
disassembly and record any abnormal conditions. It is not necessary
to measure the volume of the impingers for the purpose of moisture
determination as the method is not validated for moisture
determination. Treat samples as follows:
8.2.1 Container No. 1, Probe and Impinger Numbers 1 and 2. Rinse
and brush the probe/nozzle first with toluene twice and then twice
again with acetonitrile and place the wash into a glass container
labeled with the test run identification and “Container No. 1.”
When using these solvents ensure that proper ventilation is
available. Quantitatively transfer the liquid from the first two
impingers and the condenser into Container No. 1. Rinse the
impingers and all connecting glassware twice with toluene and then
twice again with acetonitrile and transfer the rinses into
Container No. 1. After all components have been collected in the
container, seal the container, and mark the liquid level on the
bottle.
8.2.2 Container No. 2, Impingers 3 and 4. Quantitatively
transfer the liquid from each impinger into a glass container
labeled with the test run identification and “Container No. 2.”
Rinse each impinger and all connecting glassware twice with toluene
and twice again with acetonitrile and transfer the rinses into
Container No. 2. After all components have been collected in the
container, seal the container, and mark the liquid level on the
bottle.
Note:
The contents of the fifth and sixth impinger (silica gel) can be
discarded.
8.2.3 Container No. 3, Reagent Blank. Save a portion of both
washing solutions (toluene/acetonitrile) used for the cleanup as a
blank. Transfer 200 ml of each solution directly from the wash
bottle being used and combine in a glass sample container with the
test identification and “Container No. 3.” Seal the container, and
mark the liquid level on the bottle and add the proper label.
8.2.4 Field Train Proof Blanks. To demonstrate the cleanliness
of sampling train glassware, you must prepare a full sampling train
to serve as a field train proof blank just as it would be prepared
for sampling. At a minimum, one complete sampling train will be
assembled in the field staging area, taken to the sampling area,
and leak-checked. The probe of the blank train shall be heated
during and the train will be recovered as if it were an actual test
sample. No gaseous sample will be passed through the sampling
train. Field blanks are recovered in the same manner as described
in sections 8.2.1 and 8.2.2 and must be submitted with the field
samples collected at each sampling site.
8.2.5 Field Train Spike. To demonstrate the effectiveness of the
sampling train, field handling, and recovery procedures you must
prepare a full sampling train to serve as a field train spike just
as it would be prepared for sampling. The field spike is performed
in the same manner as the field train proof blank with the
additional step of adding the Field Spike Solution to the first
impinger after the initial leak check. The train will be recovered
as if it were an actual test sample. No gaseous sample will be
passed through the sampling train. Field train spikes are recovered
in the same manner as described in sections 8.2.1 and 8.2.2 and
must be submitted with the samples collected for each test
program.
8.3 Sample Transport Procedures. Containers must remain in an
upright position at all times during shipment. Samples must also be
stored at <4 °C between the time of sampling and concentration.
Each sample should be extracted and concentrated within 30 days
after collection and analyzed within 30 days after extraction. The
extracted sample must be stored at 4 °C.
8.4 Sample Custody. Proper procedures and documentation for
sample chain of custody are critical to ensuring data integrity.
The chain of custody procedures in ASTM D4840-99 (Reapproved 2018)
e “Standard Guide for Sampling Chain-of-Custody Procedures”
(incorporated by reference, see § 63.14) shall be followed for all
samples (including field samples and blanks).
9.0 Quality Control
9.1 Sampling. Sampling Operations. The sampling quality control
procedures and acceptance criteria are listed in Table 326-2 below;
see also section 9.0 of Method 5.
9.2 Analysis. The analytical quality control procedures required
for this method includes the analysis of the field train proof
blank, field train spike, and reagent and method blanks. Analytical
quality control procedures and acceptance criteria are listed in
Table 326-3 below.
9.2.1 Check for Breakthrough. Recover and determine the
isocyanate(s) concentration of the last two impingers separately
from the first two impingers.
9.2.2 Field Train Proof Blank. Field blanks must be submitted
with the samples collected at each sampling site.
9.2.3 Reagent Blank and Field Train Spike. At least one reagent
blank and a field train spike must be submitted with the samples
collected for each test program.
9.2.4 Determination of Method Detection Limit. Based on your
instrument's sensitivity and linearity, determine the calibration
concentrations or masses that make up a representative low level
calibration range. The MDL must be determined at least annually for
the analytical system using an MDL study such as that found in
section 15.0 to Method 301 of appendix A to part 63 of this
chapter.
Table 326-2 - Sampling Quality Assurance
and Quality Control
QA/QC criteria |
Acceptance criteria |
Frequency |
Consequence if not met |
Sampling Equipment
Leak Checks |
≤0.00057 m3/min (0.020 cfm) or
4% of sampling rate, whichever is less |
Prior to, during (optional)
and at the completion to sampling |
Prior to: Repair and repeat
calibration. During/Completion: None, testing should be considered
invalid. |
Dry Gas Meter
Calibration - Pre-Test (individual correction factor - Yi) |
within ±2% of average factor
(individual) |
Pre-test |
Repeat calibration point. |
Dry Gas Meter
Calibration - Pre-Test (average correction factor - Yc) |
1.00 ±1% |
Pre-test |
Adjust the dry gas meter and
recalibrate. |
Dry Gas Meter
Calibration - Post-test |
Average dry gas meter
calibration factor agrees with ±5% Yc |
Each Test |
Adjust sample volumes using
the factor that gives the smallest volume. |
Temperature sensor
calibration |
Absolute temperature measures
by sensor within ±1.5% of a reference sensor |
Prior to initial use and
before each test thereafter |
Recalibrate; sensor may not be
used until specification is met. |
Barometer
calibration |
Absolute pressure measured by
instrument within ±10 mm Hg of reading with a mercury barometer or
NIST traceable barometer |
Prior to initial use and
before each test thereafter |
Recalibrate; instrument may
not be used until specification is met. |
Table 326-3 - Analytical Quality Assurance
and Quality Control
QA/QC criteria |
Acceptance criteria |
Frequency |
Consequence if not met |
Calibration -
Method Blanks |
<5% level of expected
analyte |
Each analytical method
blank |
Locate source of
contamination; reanalyze. |
Calibration -
Calibration Points |
At least six calibration point
bracketing the expected range of analysis |
Each analytical batch |
Incorporate additional
calibration points to meet criteria. |
Calibration -
Linearity |
Correlation coefficient
>0.995 |
Each analytical batch |
Verify integration,
reintegrate. If necessary, recalibrate. |
Calibration -
secondary standard verification |
Within ±10% of true value |
After each calibration |
Repeat secondary standard
verification, recalibrate if necessary. |
Calibration -
continual calibration verification |
Within ±10% of true value |
Daily and after every ten
samples |
Invalidate previous ten sample
analysis, recalibrate and repeat calibration, reanalyze samples
until successful. |
Sample
Analysis |
Within the valid calibration
range |
Each sample |
Invalidate the sample if
greater than the calibration range and dilute the sample so that it
is within the calibration range. Appropriately flag any value below
the calibration range. |
Replicate
Samples |
Within ±10% of RPD |
Each sample |
Evaluate integrations and
repeat sample analysis as necessary. |
Field Train Proof
Blank |
≤10% level of expected
analyte |
Each test program |
Evaluate source of
contamination. |
Field Train
Spike |
Within ±30% of true value |
Each test program |
Evaluate performance of the
method and consider invalidating results. |
Breakthrough |
Final two impingers Mass
collected is >5% of the total mass or >20% of the total mass
when the measured results are 20% of the applicable standard.
Alternatively, there is no breakthrough requirement when the
measured results are 10% of the applicable standard |
Each test run |
Invalidate test run. |
10.0 Calibration and Standardization Note:
Maintain a laboratory log of all calibrations.
10.1 Probe Nozzle, Pitot Tube Assembly, Dry Gas Metering System,
Probe Heater, Temperature Sensors, Leak-Check of Metering System,
and Barometer. Same as Method 5, sections 10.1, 10.2, 10.3, 10.4,
10.5, 8.4.1, and 10.6, respectively.
10.2 High Performance Liquid Chromatograph. Establish the
retention times for the isocyanates of interest; retention times
will depend on the chromatographic conditions. The retention times
provided in Table 10-1 are provided as a guide to relative
retention times when using a C18, 250 mm x 4.6 mm ID, 5µm particle
size column, a 2 ml/min flow rate of a 1:9 to 6:4
Acetonitrile/Ammonium Acetate Buffer, a 50 µl sample loop, and a UV
detector set at 254 nm.
Table 326-4 - Example Retention Times
Retention
times |
Compound |
Retention
time
(minutes) |
MI |
10.0 |
1,6-HDI |
19.9 |
2,4-TDI |
27.1 |
MDI |
27.3 |
10.3 Preparation of Isocyanate Derivatives.
10.3.1 HDI, TDI, MDI. Dissolve 500 mg of each isocyanate in
individual 100 ml aliquots of methylene chloride (MeCl2), except
MDI which requires 250 ml of MeCl2. Transfer a 5-ml aliquot of
1,2-PP (see section 7.3.8) to each solution, stir and allow to
stand overnight at room temperature. Transfer 150 ml aliquots of
hexane to each solution to precipitate the isocyanate-urea
derivative. Using a Buchner funnel, vacuum filter the
solid-isocyanate-urea derivative and rinse with 50 ml of hexane.
Dissolve the precipitate in a minimum aliquot of MeCl2. Repeat the
hexane precipitation and filtration twice. After the third
filtration, dry the crystals at 50 °C and transfer to bottles for
storage. The crystals are stable for at least 21 months when stored
at room temperature in a closed container.
10.3.2 MI. Prepare a 200 µg/ml stock solution of methyl
isocyanate-urea, transfer 60 mg of 1,2-PP to a 100-ml volumetric
flask containing 50 ml of MeCl2. Carefully transfer 20 mg of methyl
isocyanate to the volumetric flask and shake for 2 minutes. Dilute
the solution to volume with MeCl2 and transfer to a bottle for
storage. Methyl isocyanate does not produce a solid derivative and
standards must be prepared from this stock solution.
10.4 Preparation of calibration standards. Prepare a 100 µg/ml
stock solution of the isocyanates of interest from the individual
isocyanate-urea derivative as prepared in sections 10.3.1 and
10.3.2. This is accomplished by dissolving 1 mg of each
isocyanate-urea derivative in 10 ml of Acetonitrile. Calibration
standards are prepared from this stock solution by making
appropriate dilutions of aliquots of the stock into
Acetonitrile.
10.5 Preparation of Method Blanks. Prepare a method blank for
each test program (up to twenty samples) by transferring 300 ml of
the absorption solution to a 1,000-ml round bottom flask and
concentrate as outlined in section 11.2.
10.6 Preparation of Field Spike Solution. Prepare a field spike
solution for every test program in the same manner as calibration
standards (see Section 10.4). The mass of the target isocyanate in
the volume of the spike solution for the field spike train shall be
equivalent to that estimated to be captured from the source
concentration for each compound; alternatively, you may also
prepare a solution that represents half the applicable
standard.
10.7 HPLC Calibrations. See Section 11.1.
11.0 Analytical Procedure
11.1 Analytical Calibration. Perform a multipoint calibration of
the instrument at six or more upscale points over the desired
quantitative range (multiple calibration ranges shall be
calibrated, if necessary). The field samples analyzed must fall
within at least one of the calibrated quantitative ranges and meet
the performance criteria specified below. The lowest point in your
calibration curve must be at least 5, and preferably 10, times the
MDL. For each calibration curve, the value of the square of the
linear correlation coefficient, i.e., r 2, must be ≥0.995,
and the analyzer response must be within ±10 percent of the
reference value at each upscale calibration point. Calibrations
must be performed on each day of the analysis, before analyzing any
of the samples. Following calibration, a secondary standard shall
be analyzed. A continual calibration verification (CCV) must also
be performed prior to any sample and after every ten samples. The
measured value of this independently prepared standard must be
within ±10 percent of the expected value. Report the results for
each calibration standard secondary standard, and CCV as well as
the conditions of the HPLC. The reports should include at least the
peak area, height, and retention time for each isocyanate compound
measured as well as a chromatogram for each standard.
11.2 Concentration of Samples. Transfer each sample to a
1,000-ml round bottom flask. Attach the flask to a rotary
evaporator and gently evaporate to dryness under vacuum in a 65 °C
water bath. Rinse the round bottom flask three times each with 2 ml
of acetonitrile and transfer the rinse to a 10-ml volumetric flask.
Dilute the sample to volume with acetonitrile and transfer to a
15-ml vial and seal with a PTFE lined lid. Store the vial ≤4 °C
until analysis.
11.3 Analysis. Analyze replicative samples by HPLC, using the
appropriate conditions established in section 10.2. The width of
the retention time window used to make identifications should be
based upon measurements of actual retention time variations of
standards over the course of a day. Three times the standard
deviation of a retention time for a compound can be used to
calculate a suggested window size; however, the experience of the
analyst should weigh heavily in the interpretation of the
chromatograms. If the peak area exceeds the linear range of the
calibration curve, the sample must be diluted with acetonitrile and
reanalyzed. Average the replicate results for each run. For each
sample you must report the same information required for analytical
calibrations (Section 11.1). For non-detect or values below the
detection limit of the method, you shall report the value as “<”
numerical detection limit.
12.0 Data Analysis and Calculations
Nomenclature and calculations, same as in Method 5, section 6,
with the following additions below.
12.1 Nomenclature.
AS = Response of the sample, area counts. b = Y-intercept of the
linear regression line, area counts. BR = Percent Breakthrough CA =
Concentration of a specific isocyanate compound in the initial
sample, µg/ml. CB = Concentration of a specific isocyanate compound
in the replicate sample, µg/ml. CI = Concentration of a specific
isocyanate compound in the sample, µg/ml. Crec = Concentration
recovered from spike train, µg/ml. CS = Concentration of isocyanate
compound in the stack gas, µg/dscm CT = Concentration of a specific
isocyanate compound (Impingers 1-4), µg/dscm Cspike = Concentration
spiked, µg/ml. C4 = Concentration of a specific isocyanate compound
(Impingers 14), µg/dscm FIm = Mass of Free Isocyanate FTSrec =
Field Train Spike Recovery Im = Mass of the Isocyanate Imw = MW of
the Isocyanate IUm = Mass of Isocyanate-urea derivative IUmw = MW
of the isocyanate-urea M = Slope of the linear regression line,
area counts-ml/µg. mI = Mass of isocyanate in the total sample MW =
Molecular weight RPD = Relative Percent Difference VF = Final
volume of concentrated sample, typically 10 ml. Vmstd = Volume of
gas sample measured by the dry-gas meter, corrected to standard
conditions, dscm (dscf).
12.2 Conversion from Isocyanate to the Isocyanate-urea
derivative. The equation for converting the amount of free
isocyanate to the corresponding amount of isocyanate-urea
derivative is as follows:
12.2 Conversion from Isocyanate to the Isocyanate-urea
derivative. The equation for converting the amount of free
isocyante to the corresponding amount of isocyante-urea derivative
is as follows:

The
equation for converting the amount of IU derivative to the
corresponding amount of FLm is as follows:
12.3 Calculate the correlation coefficient, slope, and
intercepts for the calibration data using the least squares method
for linear regression. Concentrations are expressed as the
x-variable and response is expressed as the y-variable.
12.4 Calculate the concentration of isocyanate in the
sample:
12.5 Calculate the total amount collected in the sample by
multiplying the concentration (µg/ml) times the final volume of
acetonitrile (10 ml).
12.6 Calculate the concentration of isocyanate (µg/dscm) in the
stack gas.
12.7 Calculate Relative Percent Difference (RPD) for each
replicative sample
12.8 Calculate Field Train Spike Recovery
12.9 Calculate Percent Breakthrough

Where: K
= 35.314 ft 3/m 3 if Vm(std) is expressed in English units. = 1.00
m 3/m 3 if Vm(std) is expressed in metric units. 13.0 Method
Performance
Evaluation of sampling and analytical procedures for a selected
series of compounds must meet the quality control criteria (See
Section 9) for each associated analytical determination. The
sampling and analytical procedures must be challenged by the test
compounds spiked at appropriate levels and carried through the
procedures.
14.0 Pollution Prevention [Reserved] 15.0 Waste Management
[
Reserved] 16.0 Alternative Procedures [Reserved] 17.0
References 1. Martin, R.M., Construction Details of Isokinetic
Source-Sampling Equipment, Research Triangle Park, NC, U.S.
Environmental Protection Agency, April 1971, PB-203 060/BE,
APTD-0581, 35 pp. 2. Rom, J.J., Maintenance, Calibration, and
Operation of Isokinetic Source Sampling Equipment, Research
Triangle Park, NC, U.S. Environmental Protection Agency, March
1972, PB-209 022/BE, APTD-0576, 39 pp. 3. Schlickenrieder, L.M.,
Adams, J.W., and Thrun, K.E., Modified Method 5 Train and Source
Assessment Sampling System: Operator's Manual, U.S. Environmental
Protection Agency, EPA/600/8-85/003/1985). 4. Shigehara, R.T.,
Adjustments in the EPA Nomograph for Different Pitot Tube
Coefficients and Dry Molecular Weights, Stack Sampling News, 2:4-11
(October 1974). 5. U.S. Environmental Protection Agency, 40 CFR
part 60, Appendices A-1, A-2, and A-3, Methods 1-5. 6. Vollaro,
R.F., A Survey of Commercially Available Instrumentation for the
Measurement of Low-Range Gas Velocities, Research Triangle Park,
NC, U.S. Environmental Protection Agency, Emissions Measurement
Branch, November 1976 (unpublished paper). 18.0 Diagrams

[57 FR 61992, Dec.
29, 1992] Editorial Note:For Federal Register citations affecting
appendix A to part 63, see the List of CFR Sections Affected, which
appears in the Finding Aids section of the printed volume and at
www.govinfo.gov.