Monitoring Methods Adaptable to Vapor Intrusion Monitoring - USEPA Compendium
Methods TO-15, TO-15 Supplement (Draft), and TO-17
William A. McClenny, U.S. EPA, Research Triangle Park, NC, USA, Karen D. Oliver, H.
Herbert Jacumin, Jr., and E. Hunter Daughtrey, Jr., ManTech Environmental Technology,
Inc., Research Triangle Park, NC, USA
Abstract - USEPA ambient air monitoring methods for volatile organic compounds (VOCs)
using specially-prepared canisters and solid adsorbents are directly adaptable to monitoring for
vapors in the indoor environment. The draft Method TO-15 Supplement, an extension of the
USEPA Method TO-15, highlights the lowering of VOC detection limits to single digit parts-per-
trillion by volume (pptv) concentrations using canister-based sampling along with analysis by
benchtop GC/MS . Diffusive sampling onto adsorbent-filled sampling tubes similar to those
described in TO-17 is being evaluated for sampling periods of 24 hours and less. Initial results
indicate a linearity of response at the 2 parts-per-billion by volume (ppbv) level and excellent
duplicate runs.
Introduction
The Office of Research and Development (ORD), USEPA has recently provided guidance
on evaluating vapor intrusion into indoor air through an exposure pathway originating from
contaminated groundwater and soils.1 Part of this guidance involves screening indoor
environments for potential or actual vapor intrusion of toxic gases. Among other activities the
screening involves establishing the level of toxic VOCs in the soil gas directly below the indoor
space. A basic premise of the guidance is that atypically high soil gas concentrations warrant
remediation whether or not toxic soil gases are intruding into the indoor space. The key
determination to trigger remediation is whether the soil gases reach levels that are causing or can
potentially cause harmful exposures in the indoor environment. Indoor air monitoring by the
EPA Compendium Methods TO-152 and TO-173 provides VOC concentration data with a
method detection limit (MDL) at or near 0.5 ppbv in air. The TO-15 Method addresses canister-
based and other monitoring approaches in which air is sampled into specially-prepared canisters
for storage and transport prior to analysis by gas chromatography/mass spectrometry (GC/MS).
The TO-17 Method addresses solid adsorbent-based monitoring in which air is sampled by
pulling air through containers (tubes or badges) filled with carbon-based adsorbents such as
graphitic carbon or carbon molecular sieves or through porous polymer adsorbents such as
Tenax. After sampling, the adsorbent containers are stored and transported to a laboratory where
the VOCs are thermally desorbed at elevated temperatures and analyzed by GC/MS.
In this presentation, recent extensions to the methods TO-15 and TO-17 are discussed.
These extensions should enhance the usefulness of these methods in indoor monitoring
applications such as vapor intrusion. Possible applications to vapor intrusion monitoring include
answering the question of whether VOC concentrations are reduced as a result of remediation
and by how much. Also, if indoor air concentrations are determined to be low even though soil
gas concentrations are atypically high, remedial actions can be delayed in favor of higher priority
remediation.

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Recent Research Activities
Recent ORD research projects are enhancing VOC monitoring capabilities in response to
interest in vapor intrusion and to interest in exposure monitoring. One of these projects, the
development of the TO-15 Supplement, has established that the MDL for 1,1-dichloroethene
(1,1-DCE) can be improved to a concentration of 6 pptv. Because of the similarity of detection
approaches for other VOCs, improved MDLs for many other VOCs are also likely. A second
project is the investigation of the use of adsorbent-based sampling tubes of the type used in TO-
17 for diffusive sampling. The diffusive sampling approach requires no pumps or power sources
for sampling; however, typical sampling rates require several hours to accumulate VOCs in the
low picogram (pg) quantities required for accurate detection. Sampling times of up to 24 hours
under typical indoor monitoring conditions indicate sub-ppbv detection of representative toxic
VOCs.
Extensions of the EPA Compendium Method TO-15
Although still in draft form,4 Method TO-15 has recently been extended by demonstrating
the use of currently available benchtop GC/MS systems to achieve MDLs in the single digit pptv
range (a few pg) for 1,1-DCE. In the process of determining this in the EPA laboratories, the
capability to generate low-level sample blanks essentially devoid of 1,1-DCE and to generate
stable standards of 1,1-DCE at 30-60 pptv in humidified air have been demonstrated. Using
these capabilities, canister samples were prepared for analysis by three contract laboratories.
These samples contained 1,1-DCE at concentrations as low as 30 pptv. Comparison of their
results for what to them were unknown samples are shown in Table 1. There were four sample
matrices, including humidified zero air, ambient air plus 1,1-DCE, ambient air plus 1,1-DCE and
other chlorinated compounds, and a synthetic mixture of sixty hydrocarbons.
Based on the agreement among the laboratories at low-pptv levels, a reduction in the
MDL from the concentration of 0.5 ppbv stated in Method TO-15 seems warranted. Although
this experiment does not necessarily indicate by itself that the MDLs for other toxic VOCs could
be lowered, the likelihood of this is implied. The TO-15 Supplement also documents the use of
specially-prepared stainless steel canisters, canister cleaning apparatus, and compressed gas
standards from commercially available sources to provide stable low-level (<100 pptv)
concentrations of 1,1-DCE and, by implication, other toxic VOCs.
Extensions of the EPA Compendium Method TO-17
Adsorbent-based sampling has been evaluated and standardized over the years by a
number of scientists. Much of this development is restated and supplemented in EPA
Compendium Method TO-17 and in recently released documents published by the International
Standards Organization (ISO) for adsorbent-based sampling using air pumps (ISO-16017-1) and
for diffusive sampling with adsorbent-filled tubes (ISO-16017-2).5 A single standard covering
both active and passive sampling is scheduled to be published by the ASTM International in the
fall of 2003 with the designation ASTM-D 6196-03.6
Recent work at the EPA involves the use of diffusive sampling devices to estimate
exposure to various toxic VOCs. The samplers are the standard axial diffusive sampling tubes

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described in EPA Method TO-17 and elsewhere; i.e., stainless steel tubes 9 cm in length, 5 mm
inside diameter and 6 mm outside diameter, and which are available from a number of
companies. When used as diffusive samplers, the tubes are sealed at one end and an open cap
with a fine wire mesh diffusion barrier is placed on the opposite end. Gases diffuse into an empty
gap between the cap and a packing of solid adsorbent and onto the solid adsorbent.
Data is currently being generated by the EPA using an exposure chamber in which the
tubes can be exposed to known concentrations of toxic VOCs under different conditions of air
velocity, humidity, and temperature. The analytical system is a PerkinElmer TurboMatrix ATD
(automated thermal desorber) for desorbing the adsorbent-filled tubes. It is connected to a Perkin
Elmer AutoSystem XL GC/TurboMass Gold MS through a heated 1.5-m length of 0.32-mm-i.d.
DB-1 capillary column (Agilent Technologies, Wilmington, DE). A 60-m by 0.32-mm-i.d. by
1.0-(im DB-1 capillary column is used for separation of analytes.
Figure 1 shows an example of data indicating the linearity of response of pairs of tubes
packed with Carbopack X (Supelco, Bellefonte, PA) to 2 ppbv toluene and a mixture of VOCs in
humidified air at 35% RH and 22° C, and with a linear air speed of approximately 10 cm/sec
parallel to the tube axis. The performance of these tubes for specific gases depends on the
adsorbent material, the exposure time, and various parameters used in thermal desorption of the
tube into a GC/MS system. In one recent application two tubes were used to collect micro-
environmental samples in the basement of a single family home. Figure 2 shows the nearly
identical chromatographic results (total ion chromatograms using the MS scan mode of
operation) for this sampling event. Table 2 shows the results for those individual VOCs
corresponding to the largest peaks in Figure 2. The work presented here is part of studies in
progress to establish a capability for personal exposure and micro-environmental monitoring for
a wide range of VOCs.
Based on the preliminary results for diffusive sampling of VOCs, the use of the
assembled combination of adsorbent tubes and analytical equipment for applications in indoor air
monitoring related to vapor intrusion seems straightforward. For application in monitoring
specific gases, the appropriate adsorbent must be chosen. Guidance in doing this is provided in
TO-17 and the recent ISO 16017-1, ISO 16017-2 documents, and ASTM D6196 standards.
Disclaimer - This presentation has been subjected to the Agency's peer and administrative
review, and it has been approved for publication. Mention of trade names or commercial
products does not constitute endorsement of recommendation for use.
References
1.	U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response
(OSWER) Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from
Groundwater and Soils (Subsurface Vapor Intrusion Guidance) at
http://www.epa.gov/correctiveaction/eis/vapor.htm.
2.	U.S. Environmental Protection Agency, Compendium of Methods for the Determination of
Toxic Organic Compounds in Ambient Air, Second Edition, Compendium Method TO-15,
Determination of Volatile Organic Compounds (VOCs) in Air Collected in Specially-Prepared
Canisters and Analyzed by Gas Chromatography/Mass Spectrometry (GC/MS), Center for

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Environmental Research Information, Office of Research and Development, U.S. Environmental
Protection Agency, Cincinnati, OH 45268.
3.	U.S. Environmental Protection Agency, Compendium of Methods for the Determination of
Toxic Organic Compounds in Ambient Air, Second Edition, Compendium Methods TO-17,
Determination of Volatile Organic Compounds in Ambient Air Using Active Sampling Onto
Sorbent Tubes, Center for Environmental Research Information, Office of Research and
Development, U.S. Environmental Protection Agency, Cincinnati, OH 45268.
4.	U.S. Environmental Protection Agency, Method TO-15 Supplement - Analysis of 1,1-DCE at
pptv Concentrations, November 2002, EPA clearance pending as of June 20, 2003, National
Exposure Research Laboratory, Research Triangle Park, NC, 27711.
5.	International Standards Organization (ISO), International Standards 16017-1 and 16017-2,
Indoor, Ambient and Workplace Air - Sampling and Analysis of Volatile Organic Compounds by
Sorbent Tube/Thermal Desorption/Capillary Gas Chromatography - Part 1: Pumped Sampling
and Part 2: Diffusive Sampling, ISO, Geneva, Switzerland.
6.	ASTM International D 6196-03, Standard Practice for Selection of Sorbents, Sampling, and
Thermal Desorption Analysis Procedures for Volatile Organic Compounds in Air, Annual Book
of ASTM Standards, Vol. 11.03, American ASTM International, Wes Conshohoken, PA, 2003.

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Table 1. Comparison of Results Obtained at Three Contract Labs and the Originating Lab
for Canister Samples



Reference
Contract
Contract



System*
Lab
Lab
#
Canister
Sample
(pptv)
(pptv)
#
1
A-701
Ambient Air + 1,1-Dichloroethene
32
30
1
2
785
Ambient Air + 1,1-Dichloroethene
27
30
1
3
GA-B
Ambient Air + 1,1-Dichloroethene
30
30
1
4
120
Ambient Air + 1,1-Dichloroethene
30
28
2
5
01578
Ambient Air + 1,1-Dichloroethene
32
29
2
6
MTC-22
Ambient Air + 1,1-Dichloroethene
29
27
2
7
208
Ambient Air + 1,1-Dichloroethene
32
27
3
8
013
Ambient Air + 1,1-Dichloroethene
31
29
3
9
454
Ambient Air + 1,1-Dichloroethene
29
29
3
10
N-3
Ambient Air + Chlorinated Cmpds
69
59
1
11
726
Ambient Air + Chlorinated Cmpds
59
59
iillili
12
096
Ambient Air + Chlorinated Cmpds
60
60
2
13
727
Ambient Air + Chlorinated Cmpds
61
53
2
14
9682 B
Ambient Air + Chlorinated Cmpds
57
60
IlllllSlll:!
15
9677 B
Ambient Air + Chlorinated Cmpds
62
54
3
16
5226
Humidified Scientific Air (HSA)
ND**
ND
1
17
5962
Humidified Scientific Air (HSA)
ND
ND
1
18
1299
Humidified Scientific Air (HSA)
ND
ND
1
19
063240
Humidified Scientific Air (HSA)
ND
ND
2
20
0102
Humidified Scientific Air (HSA)
ND
ND
2
21
02303
Humidified Scientific Air (HSA)
ND
ND
2
22
JMTC 034
Humidified Scientific Air (HSA)
ND
ND
3
23
JMTC 027
Humidified Scientific Air (HSA)
ND
ND
3
24
JMTC 035
Humidified Scientific Air (HSA)
ND
ND
3
25
801
PAMS + Terpenes +1,1 -DCE
5200
5600
iiiiliii
26
465
PAMS + Terpenes + 1,1-DCE
5100
6000
llplli
27
321
PAMS + Terpenes + 1,1-DCE
5200
11700
3
* Reference System - In-house system independently calibrated.
ND = not detected, or detected amount below either MDL or RL.

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Table 2. Results of Duplicate Samples Taken in a Residential Basement - Diffusive
Sampling with Adsorbent-Filled Tubes

3a
Basement
4 a
Basement
Compound Name
RT
(Area Cts)
RT
(Area Cts)
Benzene
9.46
292637
9.46
321188
Toluene
13.71
2710089
13.71
2920344
Ethylbenzene
17.37
205572
17.37
225172
m,p-Xylene
17.67
688878
17.67
750365
o-Xylene
18.51
239221
18.51
261577
4-Ethyltoluene
20.98
66486
20.98
69732
1,3,5-Trimethylbenzene
21.15
65499
21.15
68992
1,2,4-Trimethvlbenzene
22.01
215635
22.00
222939

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Figure 2. Comparison of duplicate samples taken in a residential basement using diffusive
sampling tubes.
1QOi
ia7i	Tube3
%
9.46
1Q17
11.08
17.67
17.371

18.51

20.ee
22.01

10O1
ia7i
Ttiğ4

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TECHNICAL REPORT DATA
1. Report No. 2.
3. Recipient's Accession No.
4. Title and Subtitle/ /
Monitoring Methods Adaptable to Vapor Intrusion Monitoring -
USEPA Compendium Methods TO-15, TO-15 Supplement (Draft),
and TO-17
5.	Report Date - 27 June 2003
6.	Performing Organization Code
7. Author(s) - W.A. McCienny, USEPA; K.D. Oliver, H.H.
Jacumin, Jr., and E.H. Daughtrey, Jr., ManTech Environmental
Technology, Inc.
8. Performing Organization
Report No.
9.Performing Organization Name and Address
National Exposure Research Laboratory, U.S. Environmental
Protection Agency, Research Triangle Park, N.C. 27711
10.	Program Element No.
11.	Contract/Grant No.
12.Sponsoring Agency Name and Address
National Exposure Research Laboratory, U.S. Environmental
Protection Agency, Research Triangle Park, N.C. 27711
13.	Type of Report and Period
Covered - Symposium
Presentation - 1/1/03 - 6/30/03
14.	Sponsoring Agency Code
15. Supplementary Notes
16. Abstract - USEPA ambient air monitoring methods for volatile organic compounds using specially-
prepared canisters and solid adsorbents are directly adaptable to monitoring for vapors in the indoor
environment. The draft Method TO-15 Supplement, an extension of the USEPA Method TO-15, highlights the
lowering of VOC detection limits to single digit parts-per-trillion by volume (pptv) concentrations using
canister-based sampling along with analysis by benchtop GC/MS. Diffusive sampling onto adsorbent-filled
sampling tubes similar to those described in TO-17 is being evaluated for sampling periods of 24 hours and
less. Initial results indicate a linearity of response at the 2 parts-per-billion by volume (ppbv) level and
excellent duplicate runs.
17. KEY WORDS AND DOCUMENT ANALYSIS
A. Descriptors - volatile organic compounds,
vapor intrusion, diffusive sampling, monitoring
methods
B. Identifiers / Open Ended
Terms
C. COSATI

18. Distribution Statement - Available from the Air
and Waste Management Association, Pittsburgh,
PA, USA as part of Specialty Conference entitled
Indoor Air Quality Problems and Engineering
Solutions, July 21-23, 2003, Research Triangle
Park, NC, 27711
19. Security Class (This
Report)
21. No. of Pages - 8
20. Security Class (This
Page)
22. Price
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