Reporting.                                      with notification of
                                                                                compliance status due 150
                                                                                days after the compliance
                                                                                date, and Sec.
                                                                                63.7(g)(2) is Reserved and
                                                                                does not apply.
Sec.   63.7(h).....................  Waiver of Tests.......  Yes
Sec.   63.8(a)(1)..................  Monitoring              Yes
                                      Requirements--Applica
                                      bility.
Sec.   63.8(a)(2)..................  Performance             Yes
                                      Specifications.
Sec.   63.8(a)(3)..................  [Reserved]............  Not applicable
Sec.   63.8(a)(4)..................  Monitoring with Flares  Yes...................  Except that for a flare
                                                                                complying with Sec.
                                                                                63.670, the cross-
                                                                                reference to Sec.   63.11
                                                                                in this paragraph does not
                                                                                include Sec.   63.11(b).
Sec.   63.8(b)(1)..................  Conduct of Monitoring.  Yes
Sec.   63.8(b)(2)-(3)..............  Multiple Effluents and  Yes...................  Subpart UUU specifies the
                                      Multiple Monitoring                             required monitoring
                                      Systems.                                        locations.
Sec.   63.8(c)(1)..................  Monitoring System       Yes
                                      Operation and
                                      Maintenance.
Sec.   63.8(c)(1)(i)...............  General Duty to         No....................  See Sec.   63.1570(c).
                                      Minimize Emissions
                                      and CMS Operation.
Sec.   63.8(c)(1)(ii)..............  Keep Necessary Parts    Yes
                                      for CMS.
Sec.   63.8(c)(1)(iii).............  Requirement to Develop  No
                                      SSM Plan for CMS.
Sec.   63.8(c)(2)-(3)..............  Monitoring System       Yes...................  Except that subpart UUU
                                      Installation.                                   specifies that for
                                                                                continuous parameter
                                                                                monitoring systems,
                                                                                operational status
                                                                                verification includes
                                                                                completion of manufacturer
                                                                                written specifications or
                                                                                installation, operation,
                                                                                and calibration of the
                                                                                system or other written
                                                                                procedures that provide
                                                                                adequate assurance that
                                                                                the equipment will monitor
                                                                                accurately.
Sec.   63.8(c)(4)..................  Continuous Monitoring   Yes
                                      System Requirements.
Sec.   63.8(c)(5)..................  COMS Minimum            Yes
                                      Procedures.
Sec.   63.8(c)(6)..................  CMS Requirements......  Yes
Sec.   63.8(c)(7)-(8)..............  CMS Requirements......  Yes
Sec.   63.8(d)(1)-(2)..............  Quality Control         Yes
                                      Program for CMS.
Sec.   63.8(d)(3)..................  Written Procedures for  No
                                      CMS.
Sec.   63.8(e).....................  CMS Performance         Yes...................  Except that results are to
                                      Evaluation.                                     be submitted as part of
                                                                                the Notification
                                                                                Compliance Status due 150
                                                                                days after the compliance
                                                                                date.
Sec.   63.8(f)(1)-(5)..............  Alternative Monitoring  Yes...................  Except that subpart UUU
                                      Methods.                                        specifies procedures for
                                                                                requesting alternative
                                                                                monitoring systems and
                                                                                alternative parameters.
Sec.   63.8(f)(6)..................  Alternative to          Yes...................  Applicable to continuous
                                      Relative Accuracy                               emission monitoring
                                      Test.                                           systems if performance
                                                                                specification requires a
                                                                                relative accuracy test
                                                                                audit.
Sec.   63.8(g)(1)-(4)..............  Reduction of            Yes...................  Applies to continuous
                                      Monitoring Data.                                opacity monitoring system
                                                                                or continuous emission
                                                                                monitoring system.

Sec.   63.8(g)(5)..................  Data Reduction........  No....................  Subpart UUU specifies
                                                                                requirements.
Sec.   63.9(a).....................  Notification            Yes...................  Duplicate Notification of
                                      Requirements--Applica                           Compliance Status report
                                      bility.                                         to the Regional
                                                                                Administrator may be
                                                                                required.
Sec.   63.9(b)(1)-(2)..............  Initial Notifications.  Yes...................  Except that notification of
                                                                                construction or
                                                                                reconstruction is to be
                                                                                submitted as soon as
                                                                                practicable before startup
                                                                                but no later than 30 days
                                                                                after the effective date
                                                                                if construction or
                                                                                reconstruction had
                                                                                commenced but startup had
                                                                                not occurred before the
                                                                                effective date.
Sec.   63.9(b)(3)..................  [Reserved]............  Not applicable
Sec.   63.9(b)(4)-(5)..............  Initial Notification    Yes...................  Except Sec.
                                      Information.                                    63.9(b)(4)(ii)-(iv), which
                                                                                are Reserved and do not
                                                                                apply.
Sec.   63.9(c).....................  Request for Extension   Yes
                                      of Compliance.
Sec.   63.9(d).....................  New Source              Yes
                                      Notification for
                                      Special Compliance
                                      Requirements.
Sec.   63.9(e).....................  Notification of         Yes...................  Except that notification is
                                      Performance Test.                               required at least 30 days
                                                                                before test.
Sec.   63.9(f).....................  Notification of VE/     Yes
                                      Opacity Test.
Sec.   63.9(g).....................  Additional              Yes
                                      Notification
                                      Requirements for
                                      Sources with
                                      Continuous Monitoring
                                      Systems.
Sec.   63.9(h).....................  Notification of         Yes...................  Except that subpart UUU
                                      Compliance Status.                              specifies the notification
                                                                                is due no later than 150
                                                                                days after compliance
                                                                                date, and except that the
                                                                                reference to Sec.
                                                                                63.5(d)(1)(ii)(H) in Sec.
                                                                                63.9(h)(5) does not
                                                                                apply.
Sec.   63.9(i).....................  Adjustment of           Yes
                                      Deadlines.
Sec.   63.9(j).....................  Change in Previous      Yes
                                      Information.
63.10(a)...........................  Recordkeeping and       Yes
                                      Reporting
                                      Applicability.
Sec.   63.10(b)(1).................  General Recordkeeping   Yes
                                      Requirements.
Sec.   63.10(b)(2)(i)..............  Recordkeeping of        No
                                      Occurrence and
                                      Duration of Startups
                                      and Shutdowns.
Sec.   63.10(b)(2)(ii).............  Recordkeeping of        No....................  See Sec.   63.1576(a)(2)
                                      Malfunctions.                                   for recordkeeping of (1)
                                                                                date, time and duration;
                                                                                (2) listing of affected
                                                                                source or equipment, and
                                                                                an estimate of the volume
                                                                                of each regulated
                                                                                pollutant emitted over the
                                                                                standard; and (3) actions
                                                                                taken to minimize
                                                                                emissions and correct the
                                                                                failure.
Sec.   63.10(b)(2)(iii)............  Maintenance Records...  Yes
Sec.   63.10(b)(2)(iv)-(v).........  Actions Taken to        No
                                      Minimize Emissions
                                      During SSM.
Sec.   63.10(b)(2)(vi).............  Recordkeeping for CMS   Yes
                                      Malfunctions.
Sec.   63.10(b)(2)(vii)-(xiv)......  Other CMS Requirements  Yes
Sec.   63.10(b)(3).................  Recordkeeping for       Yes
                                      Applicability
                                      Determinations..
Sec.   63.10(c)(1)-(6).............  Additional Records for  Yes...................  Except Sec.   63.10(c)(2)-
                                      Continuous Monitoring                           (4), which are Reserved
                                      Systems.                                        and do not apply.
Sec.   63.10(c)(7)-(8).............  Additional              Yes
                                      Recordkeeping
                                      Requirements for CMS--
                                      Identifying
                                      Exceedances and
                                      Excess Emissions.
Sec.   63.10(c)(9).................  [Reserved]............  Not applicable
Sec.   63.10(c)(10)................  Recording Nature and    No....................  See Sec.   63.1576(a)(2)
                                      Cause of Malfunctions.                          for malfunctions
                                                                                recordkeeping
                                                                                requirements.
Sec.   63.10(c)(11)................  Recording Corrective    No....................  See Sec.   63.1576(a)(2)
                                      Actions.                                        for malfunctions
                                                                                recordkeeping
                                                                                requirements.
Sec.   63.10(c)(12)-(14)...........  Additional CMS          Yes
                                      Recordkeeping
                                      Requirements.
Sec.   63.10(c)(15)................  Use of SSM Plan.......  No
Sec.   63.10(d)(1).................  General Reporting       Yes
                                      Requirements.

Sec.   63.10(d)(2).................  Performance Test        No....................  Subpart UUU requires
                                      Results.                                        performance test results
                                                                                to be reported as part of
                                                                                the Notification of
                                                                                Compliance Status due 150
                                                                                days after the compliance
                                                                                date.
Sec.   63.10(d)(3).................  Opacity or VE           Yes
                                      Observations.
Sec.   63.10(d)(4).................  Progress Reports......  Yes
Sec.   63.10(d)(5).................  SSM Reports...........  No....................  See Sec.   63.1575(d) for
                                                                                CPMS malfunction reporting
                                                                                and Sec.   63.1575(e) for
                                                                                COMS and CEMS malfunction
                                                                                reporting.
Sec.   63.10(e)(1)-(2).............  Additional CMS Reports  Yes...................  Except that reports of
                                                                                performance evaluations
                                                                                must be submitted in
                                                                                Notification of Compliance
                                                                                Status.
Sec.   63.10(e)(3).................  Excess Emissions/CMS    No....................  Subpart UUU specifies the
                                      Performance Reports.                            applicable requirements.
Sec.   63.10(e)(4).................  COMS Data Reports.....  Yes
Sec.   63.10(f)....................  Recordkeeping/          Yes
                                      Reporting Waiver.
Sec.   63.11(a)....................  Control Device and      Yes
                                      Work Practice
                                      Requirements--Applica
                                      bility.
Sec.   63.11(b)....................  Flares................  Yes...................  Except that flares
                                                                                complying with Sec.
                                                                                63.670 are not subject to
                                                                                the requirements of Sec.
                                                                                63.11(b).
Sec.   63.11(c)-(e)................  Alternative Work        Yes
                                      Practice for
                                      Monitoring Equipment
                                      for Leaks.
Sec.   63.12.......................  State Authority and     Yes
                                      Delegations.
Sec.   63.13.......................  Addresses.............  Yes
Sec.   63.14.......................  Incorporation by        Yes
                                      Reference.
Sec.   63.15.......................  Availability of         Yes
                                      Information and
                                      Confidentiality.
Sec.   63.16.......................  Performance Track       Yes
                                      Provisions.
----------------------------------------------------------------------------------------------------------------

0
88. Appendix A to subpart UUU of part 63 is amended by:
0
a. Revising the first sentence of section 2.1; and
0
b. Revising section 7.1.3.
    The revisions read as follows:

Appendix A to Subpart UUU of Part 63--Determination of Metal
Concentration on Catalyst Particles (Instrumental Analyzer Procedure)

* * * * *
    2.1 A representative sample of catalyst particles is collected,
prepared, and analyzed for analyte concentration using either energy
or wavelength dispersive X-ray fluorescent (XRF) spectrometry
instrumental analyzers. * * *
* * * * *
    7.1.3 Low-Range Calibration Standard. Concentration equivalent
to 1 to 20 percent of the span. The concentration of the low-range
calibration standard should be selected so that it is less than
either one-fourth of the applicable concentration limit or of the
lowest concentration anticipated in the catalyst samples.
* * * * *

Appendix A to Part 63--[AMENDED]

0
89. Appendix A to part 63 is amended by adding Method 325A and Method
325B to read as follows:

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 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 and 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 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 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 ([micro]g/m\3\) to at least 500 [micro]g/
m\3\ when industry standard (3.5 inch long x 0.25 inch outside
diameter (o.d.) x 5 mm inner diameter (i.d.)) stainless steel
sorbent tubes packed with Carbograph 1 TD\TM\, Carbopack B\TM\, or
Carbopack X[supreg] 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 over an extended
period of time using multiple sampling episodes (e.g., 26 x 14-day
sampling episodes). The duration of each sampling period must be 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 the fenceline
or facility 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 the facility fenceline or property boundaries and collection of
local meteorological data. It may be used to determine average
concentration of VOC at a facility fenceline or property boundaries
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.
    <IP_ADDRESS> 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.
    <IP_ADDRESS> 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.
    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 Retention volume is the maximum mass of VOC that can be
collected before the capacity of the sorbent is exceeded and back
diffusion of the VOC from the tube occurs.
    3.8 Sampling episode is the length of time each passive sampler
is exposed during field monitoring. The sampling episode for this
method is 14 days.
    3.9 Sorbent tube (Also referred to as tube, PS tube, sorbent
tube, and sampling tube) is a stainless steel or inert coated
stainless steel tube. Standard PS tube dimensions for this method
are 3.5-inch (89 mm) long x 0.25-inch (6.4 mm) o.d. stainless steel
tubes 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 x 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. General guidance
for siting can be found in EPA-454/B-13-003, Quality Assurance
Handbook for Air Pollution Measurement Systems, Volume II: Ambient
Air Quality Monitoring Program, May 2013 (Reference 3) (incorporated
by reference--see Sec.  63.14). 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 excludes 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 [deg]C (References 6,7). Note that most
published passive uptake rate data for sorbent tubes is quoted at 20
[deg]C. Note also that, as a rough guide, an increase in temperature
of 10 [deg]C will reduce the retention

volume (i.e., 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 fenceline
or 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
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 that 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 (2009) (Reference 14) (incorporated by reference--see
Sec.  63.14) and ISO 16017-2:2003 (Reference 13) (incorporated by
reference--see Sec.  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).
[GRAPHIC] [TIFF OMITTED] TP30JN14.026

    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 (Reference 13)
(incorporated by reference--see Sec.  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, Quality Assurance Handbook for Air Pollution Measurement
Systems, Volume IV: Meteorological Measurements, Version 2.0
(Final), March 2008 (Reference 11) (incorporated by reference--see
Sec.  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 boundary. You will place passive samplers on the
facility property boundary at different angles circling the
geometric center of the facility based on the size of the area (or
subarea) or at different distances based on the size and boundary
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.
    8.2.2 Option 1 for Determining Sampling Locations.
    <IP_ADDRESS> For facilities with a regular (circular, triangular,
rectangular, or square) shape, determine the geographic center of
the facility.
    <IP_ADDRESS>.1 For regularly shaped facilities with an area of less
than or equal to 750 acres, measure angles around the center point
of 30 degrees for a total of twelve 30 degree measurements.
    <IP_ADDRESS>.2 For regularly shaped facilities covering an area
greater than 750 acres but less than or equal to 1,500 acres,
measure from the center point angles of 20 degrees for a total of
eighteen 20 degree measurements. 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.
    <IP_ADDRESS>.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.
    <IP_ADDRESS>.4 Place samplers securely on a pole or supporting
structure at 1.5 to 3 meters above ground level at each point just
beyond the intersection where the measured angle intersects the
property boundary.
    <IP_ADDRESS>.5 Extra samplers must be placed near known sources of
VOCs at the test facility. In the case that a potential emission
source is within 50 meters of the property boundary and the source
location is between two monitors, measure the distance (x) between
the two monitors and place another monitor halfway between (x/2) the
two monitors. For example, in Figure 8.1 the facility added three
additional monitors (i.e., light shaded sampler locations) to
provide sufficient coverage of all area sources.
[GRAPHIC] [TIFF OMITTED] TP30JN14.027

    <IP_ADDRESS> 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.
    <IP_ADDRESS>.1 If a subarea is less than or equal to 750 acres (e.g.,
Figure 8.2), measure angles of 30 degrees from the center point for
a total of twelve 30 degree measurements.
[GRAPHIC] [TIFF OMITTED] TP30JN14.028

    <IP_ADDRESS>.2 If a subarea is greater than 750 acres but less than
or equal to 1,500 acres (e.g., Figure 8.3), measure angles of 20
degrees from the center point for a total of eighteen 20 degree
measurements.
    <IP_ADDRESS>.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.
    <IP_ADDRESS> Locate each sampling point just beyond the intersection
of the measured angle and the outer property boundary.
    <IP_ADDRESS> 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 more than one point
along the subarea's outer boundary.

[GRAPHIC] [TIFF OMITTED] TP30JN14.029

    8.2.3 Option 2 for Determining Sampling Locations.
    <IP_ADDRESS> For facilities with a boundary length of less than
24,000 feet, a minimum of twelve sampling locations evenly spaced
 10 percent of the location interval is required.
    <IP_ADDRESS> For facilities with a boundary length greater than
24,000 feet, sampling locations are spaced 2,000 250
feet apart.
    <IP_ADDRESS> Place samplers securely on a pole or supporting
structure at 1.5 to 3 meters above ground level.
    <IP_ADDRESS> Extra samplers must be placed near known sources of VOCs
at the test facility. In the case that a potential emission source
is within 50 meters of the property boundary and the source location
is between two monitors, measure the distance (x) between the two
monitors and place another monitor halfway between (x/2) the two
monitors. For example, in Figure 8.4, the facility added three
additional monitors (i.e., light shaded sampler locations) to
provide sufficient coverage of all area sources.

[GRAPHIC] [TIFF OMITTED] TP30JN14.030

    8.3 Siting a Meteorological Station. A dedicated 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, Meteorological Monitoring Guidance for Regulatory
Modeling Applications, February 2000 (Reference 11) (incorporated by
reference--see Sec.  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. 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 from large paved areas.
    8.3.4 Collect and record meteorological data, including wind
speed, wind direction, and temperature and average data on an hourly
basis. Collect daily unit vector wind direction data plus average
temperature and barometric pressure measurements of the sampled air
to enable calculation of concentrations at standard conditions.
    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 from 48
hours 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. The sampling tubes must be changed at
approximately the same time of day at each of the monitoring sites.
    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 at a height of 1.5 to 2 meters
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 at at least
one monitoring location during each field monitoring exercise.
    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 14-day sampling period.
    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. One field blank tube is
required for every 10 sampled tubes on a monitoring exercise. No

less than two field blanks should be collected, regardless of the
size of the monitoring study. Record the tube number(s) for the
field blank(s) on the field sample data sheet.
    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.
    8.6.6 Collect daily unit vector wind direction data plus average
temperature and barometric pressure measurements to enable
calculation of concentrations at standard conditions. You must
supply this information to the laboratory with the samples.

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
[deg] and 270 [deg]) 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, Quality Assurance
Handbook for Air Pollution Measurement Systems, Volume IV:
Meteorological Measurements, Version 2.0 (Final), March 2008
(Reference 11) (incorporated by reference--see Sec.  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) can be calculated for
any specified period at each PS location using Equation 12.1.
[GRAPHIC] [TIFF OMITTED] TP30JN14.031

Where:

PSi = Annual average for location i.
PSip = Sampling period specific concentration from Method
325B.
i = Location of passive sampler (0 to 360 [deg]).
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 episodes 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 episode
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 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.

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 Measurement 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, 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(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

[GRAPHIC] [TIFF OMITTED] TP30JN14.032

[GRAPHIC] [TIFF OMITTED] TP30JN14.033

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 Carbopack X or equivalent 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 a given compound or set of the compounds listed in 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 Appendix A to this method 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 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 desorping the sampling tube, refocusing on a focusing
trap, desorping 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 back diffusion
becomes significant--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 Calibration verification sample. 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 [mu]m or less
and with a stationary phase film thickness of 5 [mu]m 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 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.
    3.10 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.
    3.11 o.d. is outer diameter.
    3.12 ppbv is parts per billion by volume.
    3.13 Retention volume is the volume of gas required to move an
analyte vapor plug through the sorbent tube at a given temperature
during active (pumped) sampling. Note that retention volume provides
another measure of the strength of sorbent:sorbate (analyte)
affinity and is closely related to breakthrough volume--See
discussion in Section 3.2 above.
    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 means 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 polymer
Tenax[supreg] 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.
[GRAPHIC] [TIFF OMITTED] TP30JN14.034

    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 only be used for tube conditioning only
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 [deg]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[supreg]-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 [deg]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 [eta]g 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 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 (incorporated by reference--see Sec.  63.14) or
ASTM D6196-03(2009) (incorporated by reference--see Sec.  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 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 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.
    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 yearly 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 [micro]l 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 [deg]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
----------------------------------------------------------------------------------------------------------------
                                                              Maximum          Conditioning
                    Sampling sorbent                        temperature        temperature      Carrier gas flow
                                                              ([deg]C)           ([deg]C)             rate
----------------------------------------------------------------------------------------------------------------
Carbotrap C[supreg]....................................               >400                350        100 mL/min.
Carbopack C[supreg]
Anasorb[supreg] GCB2
Carbograph 1 TD
Carbotrap[supreg]
Carbopack B[supreg]
Anasorb[supreg] GCB1
Tenax[supreg] TA.......................................                350                330        100 mL/min.
Carbopack[supreg] X
----------------------------------------------------------------------------------------------------------------

    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 samplers will also be required:
Laboratory blanks as specified in Section 9.3.2 (two per sampling
episode minimum), field blanks as specified in Section 9.3.4 (two
per sampling episode minimum), calibration verification tubes as
specified in Section 10.9.4. (at least one per analysis sequence or
every 24 hours), and paired (duplicate) samples as specified in
Section 9.4 (at least one pair of duplicate samples 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 [deg]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 Analytical System Blank. The analytical system must be
demonstrated to be contaminant free by carrying out an analysis
without a sorbent tube--i.e., by desorbing an empty tube or by
desorbing the focusing trap alone. Since no internal standards can
be added directly to the empty tube, the system blank must have less
than or equal to 0.2 ppbv or three times the detection limit for
each target compound, whichever is larger based on the response
factors for the continuing calibration verification sample. Perform
a system 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. Flag all sample
data from analytical sequences that fail the system blank check and
provide a narrative on how the failure affects the data use.
    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 (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 and Laboratory Blanks.
    9.3.1 Field and laboratory 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 At least two laboratory blanks are required per monitoring
episode. These laboratory blanks must be stored in the laboratory
under clean controlled ambient temperature conditions throughout the
monitoring period. Analyze one laboratory blank at the beginning and
one at the end of the associated field sample runs.
    9.3.3 Laboratory blank/artifact levels must meet the
requirements of Section 9.2.2 (see also Table 17.1). Flag all data
that do not meet this criterion with a note that associated results
are estimated, and likely to be biased high due to laboratory blank
background.

    9.3.4 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 (see Method 325B). The long-term
storage caps must be in place and must be stored outside the
shipping container at the sampling location (see Method 325B). The
field blanks are then shipped back to the laboratory in the same
container as the sampled tubes. One field blank tube is required for
every 10 sampled tubes on a monitoring exercise and no less than two
field blanks should be collected, regardless of the size of the
monitoring study.
    9.3.5 Field blanks must contain no greater than one-third of the
measured target analyte or compliance limit for field samples (see
Table 17.1). 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 (collocated) 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 Limit of Detection. Determine the limit of detection under
the analytical conditions selected (see Section 11.3) using the
procedure in Section 15 of Method 301. The limit of detection 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 measure
analytes such as benzene at concentrations as low as 10 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 routine, single-level calibration verification 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.
[GRAPHIC] [TIFF OMITTED] TP30JN14.035

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 daily single-level calibration
verification checks may also be applied for this purpose.
[GRAPHIC] [TIFF OMITTED] TP30JN14.036

Where:

A1 = A measurement value taken from one spiked tube.
A2 = A measurement value taken from a second spiked tube.
[Amacr] = 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.
[GRAPHIC] [TIFF OMITTED] TP30JN14.037

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 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 [eta]g 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
----------------------------------------------------------------------------------------------------------------
\1\ All ion abundances must be normalized to m/z 95, the nominal base peak, even though the ion abundance of m/z
  174 may be up to 120 percent that of m/z 95.

    9.13 Routine Calibrations Checks at the Start of a Sequence. Run
single-level calibration checks before each sequence of analyses and
after every tenth sample to ensure that the previous multi-level
calibration (see Section 10.6.3) is still valid.
    9.13.1 The sample concentration used for the routine calibration
check 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 daily calibration standard. The percent
deviation between the initial calibration and the daily calibration
check for all compounds must be within 30 percent.
    9.14 Calibration Verification at the End of a Sequence. Run
another single level standard after running each sequence of
samples. The initial calibration check for a subsequent set of
samples may be used as the final calibration check 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 calibration verification.
    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.
    <IP_ADDRESS> 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.
    <IP_ADDRESS> 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.
    <IP_ADDRESS> 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[emsp14][deg]F.
    <IP_ADDRESS> 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 5.0 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 [micro]l aliquots of liquid
standards to the sampling end of sorbent tubes in a flow of carrier
gas using a precision syringe and an unheated injector (Section
6.6). 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.
    <IP_ADDRESS> 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 [micro]L 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 [micro]L) 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 and allowed to
warm to the temperature of the injection body. The liquid is then
quickly injected. The result is the cool liquid contacts the hot
syringe tip and the sample is completely forced into the injector
and onto the sorbent cartridge. 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.
    <IP_ADDRESS> Seal tubes with long-term storage caps immediately
after they have been disconnected from the standard loading manifold
or injection apparatus.
    <IP_ADDRESS> 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.
    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 and relevant
parts of Section 9.5.
    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
single-level calibration verification 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.
    <IP_ADDRESS> Single-level calibrations checks must be carried out on
a regular routine basis as described in Section 9.6.
    <IP_ADDRESS> 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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Characteristic ion(s)
                   Compound                         CAS No.       BP ([deg]C)     Vapor  pressure       MW \b\     -------------------------------------
                                                                                (mmHg)\a\                           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-            138                6.5             106.2                106                 91
                                                          42-3
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
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Pressure in millimeters of mercury.
\b\ Molecular weight.

11.0 Analytical Procedure

    11.1 Preparation for Sample Analysis.
    11.1.1 Each sequence of analyses must be ordered as follows:
    <IP_ADDRESS> A calibration verification.
    <IP_ADDRESS> A laboratory blank.
    <IP_ADDRESS> Field blank.
    <IP_ADDRESS> Sample(s).
    <IP_ADDRESS> Field blank.
    <IP_ADDRESS> A single-level calibration verification standard tube
after 10 field samples.
    <IP_ADDRESS> A single-level calibration verification standard tube
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.
    <IP_ADDRESS> 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.
    <IP_ADDRESS> 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.
    <IP_ADDRESS> 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
<IP_ADDRESS>.
    11.2.4 Optional dry purge.
    <IP_ADDRESS> 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.
    <IP_ADDRESS> 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.
    <IP_ADDRESS> 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.
    <IP_ADDRESS> 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.
    <IP_ADDRESS> 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.
    <IP_ADDRESS> Conduct predesorption system checks (see Section 11.2).
    <IP_ADDRESS> 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
[deg]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 [deg]C during focusing. Selection of hydrophobic sorbents
for focusing and setting a trapping temperature of +25 to 27 [deg]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 [deg]C/s) with inert (carrier) gas flowing through the
trap (3-100 mL/min) in the reverse direction to that used during
focusing.
    <IP_ADDRESS> 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 [deg]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 [micro]g samples
will require a split ratio in the order of ~50:1 and 200 [micro]g
samples will require a double split method with an overall split
ratio in the order of 2,000:1.
    <IP_ADDRESS> 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.
    <IP_ADDRESS> Heat/cool the GC oven to its starting set point.
    <IP_ADDRESS> 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.
    <IP_ADDRESS> 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.
    <IP_ADDRESS> 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 10.6.3).
System calibration remains valid as long as results from subsequent
routine, single-level calibration verification standards are within
30 percent of the most recent 5-point calibration (see Section
10.9.5). Include relevant routine, single-level calibration data in
the supporting information in the data report for each set of
samples.
    <IP_ADDRESS> 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 episode.
    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
daily unit vector wind direction, daily average temperature, and
daily average barometric pressure for the sample collection period.
See Section 8.6.5 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 episode.
    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).
    <IP_ADDRESS> Response factor (RF). Calculate the RF using Equation
12.1:
[GRAPHIC] [TIFF OMITTED] TP30JN14.038

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.

    <IP_ADDRESS> Standard deviation of the response factors
(SDRF). Calculate the SDRF using Equation
12.2:
[GRAPHIC] [TIFF OMITTED] TP30JN14.039

Where:

RFi = RF for each of the calibration compounds.
RF = Mean RF for each compound from the initial calibration.
n = Number of calibration standards.

    <IP_ADDRESS> Percent deviation (%DEV). Calculate the %DEV using
Equation 12.3:
[GRAPHIC] [TIFF OMITTED] TP30JN14.040

Where:

SDRF = Standard deviation.
RF = Mean RF for each compound from the initial calibration.

    <IP_ADDRESS> Relative percent difference (RPD). Calculate the RPD
using Equation 12.4:
[GRAPHIC] [TIFF OMITTED] TP30JN14.041

Where:

R1, R2 = Values that are being compared (i.e., response factors in
calibration verification).
    12.2.2 Determine the equivalent concentration of compounds in
atmospheres as follows.