12.2.3 For passive sorbent tube samples, calculate the
concentration of the target compound(s) in the sampled air, in
[mu]g/m\3\ by using Equation 12.5 (Reference 21).
[GRAPHIC] [TIFF OMITTED] TP30JN14.042

Where:

Cm = The concentration of target compound in the air
sampled ([mu]g/m\3\).
mmeas = The mass of the compound as measured in the
sorbent tube ([mu]g).
U = The diffusive uptake rate (sampling rate) (mL/min).
t = The exposure time (minutes).
    Note: Diffusive uptake rates 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 <IP_ADDRESS>
to <IP_ADDRESS>). Best possible limits of detection 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 for Selected Clean Air
                              Act Compounds
------------------------------------------------------------------------
                                                            Carbopack X
                        Compound                            uptake rate
                                                           (ml/min) \a\
------------------------------------------------------------------------
1,1-Dichloroethene......................................      0.570.14
3-Chloropropene.........................................      0.510.3
1,1-Dichloroethane......................................      0.570.1
1,2-Dichloroethane......................................      0.570.08
1,1,1-Trichloroethane...................................      0.510.1
Benzene.................................................      0.660.06
Carbon tetrachloride....................................      0.510.06
1,2-Dichloropropane.....................................      0.520.1
Trichloroethene.........................................       0.50.05
1,1,2-Trichloroethane...................................      0.490.13
Toluene.................................................      0.520.14
Tetrachloroethene.......................................      0.480.05
Chlorobenzene...........................................      0.510.06
Ethylbenzene............................................      0.460.07
m,p-Xylene..............................................      0.460.09
Styrene.................................................       0.50.14
o-Xylene................................................      0.460.12

p-Dichlorobenzene.......................................      0.450.05
------------------------------------------------------------------------
\a\ Reference 3, McClenny, J. Environ. Monit. 7:248-256.

    12.2.4 Correct target concentrations determined at the sampling
site temperature and atmospheric pressure to standard conditions (25
[deg]C and 760 mm mercury) using Equation 12.6 (Reference 22).
[GRAPHIC] [TIFF OMITTED] TP30JN14.043

Where:

tss = The temperature at the sampling site (K).
Pss = The pressure at the sampling site (mm Hg).

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.
    13.1 The valid range for measurement of VOC is approximately 0.5
[mu]g/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 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. ASTM D4597-10, Standard Practice for Sampling Workplace
Atmospheres to collect Gases or Vapors with Solid Sorbent Diffusive
Samplers.
22. 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.
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: 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      Daily \a\ prior to sample  Evaluation criteria       1) Retune and or
 Tune Performance Check.            analysis.                  presented in Section     2) Perform Maintenance.
                                                               9.5 and Table 9.2.
Five point calibration bracketing  Following any major        1) Percent Deviation      1) Repeat calibration
 the expected sample                change, repair or          (%DEV) of response        sample analysis.
 concentration.                     maintenance or if daily    factors 30%.
                                    CCV does not meet method
                                    requirements.
                                    Recalibration not to
                                    exceed three months.
                                                              2) Relative Retention     2) Repeat linearity
                                                               Times (RRTs) for target   check
                                                               peaks 0.06
                                                               units from mean RRT.
                                                                                3) Prepare new
                                                                                calibration standards
                                                                                as necessary and repeat
                                                                                analysis.
Calibration Verification (CCV      Following the calibration  The response factor       1) Repeat calibration
 Second source calibration          curve.                     30% DEV       check
 verification check).                                          from calibration curve
                                                               average response factor.
                                                                                2) Repeat calibration
                                                                                curve.
System Blank Analysis............  Daily \a\ following        1) <=0.2 ppbv per         1) Repeat analysis with
                                    bromofluorobenzene and     analyte or <=3 times      new blank tube.
                                    calibration check; prior   the LOD, whichever is
                                    to sample analysis.        greater.
                                                              2) Internal Standard      2) Check system for
                                                               (IS) area response        leaks, contamination.
                                                               40% and IS
                                                               Retention Time (RT)
                                                               0.33 min.
                                                               of most recent
                                                               calibration check.
                                                                                3) Analyze additional
                                                                                blank.
Blank Sorbent Tube Certification.  One tube analyzed for      <0.2 ppbv per VOC         Reclean all tubes in
                                    each batch of tubes        targeted compound or 3    batch and reanalyze.
                                    cleaned or 10 percent of   times the LOD,
                                    tubes whichever is         whichever is greater.
                                    greater.
Samples--Internal Standards......  All samples..............  IS area response 40% and IS RT       invalidation.
                                                               0.33 min.
                                                               of most recent
                                                               calibration validation.
----------------------------------------------------------------------------------------------------------------
\a\ Every 24 hours.

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[GRAPHIC] [TIFF OMITTED] TP30JN14.045

BILLING CODE 6560-50-P

[GRAPHIC] [TIFF OMITTED] TP30JN14.046

[GRAPHIC] [TIFF OMITTED] TP30JN14.047

BILLING CODE 6560-50-C

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, unless the
compound or

sorbent has already been validated and reported in one of the
following national/international standard methods: ISO 16017-2:2003
(incorporated by reference--see Sec.  63.14), ASTM D6196-03(2009)
(incorporated by reference--see Sec.  63.14), or BS EN 14662-4:2005
(incorporated by reference--see Sec.  63.14), or 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

    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
for an example exposure chamber). 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 active SUMMA
canister sampling.
    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 SUMMA
canisters. 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 generate a minimum of four exposed 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 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 measure the relative humidity in the test gas as
part of the record of the passive sorbent sampler evaluation.
    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 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 50 percent RH, and at 25 5 [deg]C. Allow the exposure chamber to equilibrate for 6
hours before starting an evaluation.
    A.8.6 The flow rate through the chamber must equal 100 percent
of the volume of the chamber per minute (i.e., one chamber air
change per minute) and 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 hourly intervals
or at the beginning, middle, and end of the exposure time, whichever
is greater.
    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.
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[GRAPHIC] [TIFF OMITTED] TP30JN14.049

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 house 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.
    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 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 X of
1.3 to 10 percent compared to active sampling using the following
uptake rates.

----------------------------------------------------------------------------------------------------------------
                                        1,3-butadiene        Estimated                             Estimated
                                       uptake rate mL/    detection  limit   Benzene  uptake    detection  limit
                                             min              (2 week)         rates mL/min         (2 week)
----------------------------------------------------------------------------------------------------------------
Carbopack X (2 week)................  0.61           0.1 ppbv           0.67 \a\          0.05 ppbv
                                              0.11 \a\
----------------------------------------------------------------------------------------------------------------
\a\ 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 X solid adsorbent followed by thermal desorption/GC/MS analysis--
  laboratory studies. J. Environ. Monit. 7:248-256.

    A.13.2 Data Analysis and Calculations for Method Evaluation
    A.13.2.1 Calculate the theoretical concentration of VOC
standards using Equation A.1.
[GRAPHIC] [TIFF OMITTED] TP30JN14.050

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.
[GRAPHIC] [TIFF OMITTED] TP30JN14.051

Where:

Mx = The mass of analyte measured on the sampling tube
([eta]g).
Ce = The theoretical exposure chamber concentration
([eta]g/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.
[GRAPHIC] [TIFF OMITTED] TP30JN14.052

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.
[GRAPHIC] [TIFF OMITTED] TP30JN14.053

    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.
[GRAPHIC] [TIFF OMITTED] TP30JN14.054

Where:

[Delta]95[percnt] = 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.
[GRAPHIC] [TIFF OMITTED] TP30JN14.055

Where:

RA = Relative accuracy.
Xi = The mean value of all Xi.
XA = The average concentration of analyte measured by the
active measurement method.
[Delta]95[percnt] = 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.

[FR Doc. 2014-12167 Filed 6-26-14; 8:45 am]
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