96-RP128.03
EPA/600/A-96/071
Interpretation and Data Quality Evaluation of Hourly Measurement of
Target VOCs by AutoGC/MS at the New Hendersonville, TN,
Southern Oxidants Study Site, June 17-27, 1995
E. Hunter Daughtrey, Jr., Jeffrey R. Adams, Christopher R. Fortune,
Keith G. Kronmiller, Karen D. Oliver
ManTecb Environmental Technology, Inc.
P.O. Box 12313
Research Triangle Park, NC 27709
William A. McClenny
National Exposure Research Laboratory
U.S. Environmental Protection Agency
79 Alexander Drive
Research Triangle Park, NC 27711

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96-RP128.03
INTRODUCTION
The North American Research Strategy for Tropospheric Ozone (NARSTO) program has sponsored
the development and evaluation of monitoring methods for volatile organic compounds (VOCs) that
are associated with the formation of tropospheric ozone. Target VOC lists have been developed that
are designed to be reflective of the VOCs of concern in ozone formation. These lists are evolving
as understanding of the processes develops.1*2 Our samples were analyzed for a target list that
included 57 ozone precursor compounds, the 41-compound TO-14 list, and 10 selected aldehydes.
Two field autoGC systems were deployed at the New Hendersonville, TN, site which was one of the
intensive measurement sites for the 1995 Southern Oxidants Study (SOS). This site, approximately
15 mi northeast of Nashville, was selected to be a downwind site, although as data in a companion
paper demonstrated,3 this was rarely the case for the June 17-27 period that we made
measurements. In this paper, quality assurance issues related to the calibration, sampling integrity,
and artifacts are discussed, and quantitative measures of data quality are described. Canister and
sorbent tube samples were also taken concurrently with some of the hourly measurements, and the
concurrent measurements are compared in this paper.
EXPERIMENTAL
Two autoGC/MS systems for monitoring VOCs in air were field tested. Both systems were housed
in an environmentally controlled trailer and required no cryogenic liquids for sample collection or
chromatographic separation.
Trailer
The outside dimensions of the mobile laboratory are 8.5 ft wide by 25.5 ft long, including the
tongue, and the inside dimensions are 8 ft by 20 ft. The laboratory is furnished with two instrument
benches, which measure 10 and 11 ft long, two gas bays that will accommodate a total of 8
cylinders, a computer desk, a storage closet, a small refrigerator, and storage shelves and drawers.
Two heating/air conditioning units (20 A, 120 V) and two ceiling ventilation fans are available for
temperature control. The laboratory is equipped with two 50-A 240-V electrical boxes and a total of
64 outlets. A telescoping meteorological tower which came with the trailer malfunctioned and was
replaced with a demountable tower. Air was taken from the 30-m-high sampling manifold (erected
by Georgia Institute of Technology) by heated transfer line into a distribution manifold that was
inside the monitoring trailer.
XonTech/Saturn System
One autoGC system includes a prototype sample preconcentrator designed by XonTech, Inc. (Van
Nuys, CA), that is based on the Stirling refrigeration cycle. This preconcentrator is interfaced to a
Varian Saturn II GC/Ion Trap mass spectrometer (Walnut Creek, CA), The preconcentration system
consists of two multisorbent traps (Tenax-GR/Carbotrap B/Carbosieve S-HJ) for sample collection at
ambient temperatures. Once the air sample has been concentrated on the trap, the sample is
desorbed onto a second (unpacked) trap which has been cooled to -165 °C by the Stirling closed-
cycle cooler. The sample is effectively focused on this second trap so that upon desorption at
100 °C to the GC column, the analytes are well separated without using subambient GC oven
temperature programming. After separation on the Varian Star 3400 GC column, the analytes are
detected with the Saturn ion trap detector. The system has been evaluated with the TO-14
2

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96-RP128.03
compound mixture, a polar VOC mixture, and the ozone precursor mixture. Excellent results have
been achieved with regard to trapping efficiency and linearity of response.4
Perkin Elmer ATD 400/Q-Mass 910 System
The second benchtop GC/MS system to be evaluated was made available to EPA by the Perkin
Elmer corporation (Norwalk, CT) and it includes an ATD 400 Auto Thermal Desorption system, an
Autosystem gas chromatograph, and a Q-Mass 910 mass spectrometer. The ATD 400 is the sample
concentration and desorption device for the system, and it incorporates a multisorbent packed cold
trap that is cooled by a Peltier cooler. The ATD 400 is connected to the Autosystem GC through a
heated transfer line that is connected within the GC oven to a high-capacity, fused-silica capillary
column (50 m x 0.32 mm x 5.0 #tm dimethyl polysiloxane). The GC column is connected to the
Q-Mass 910 quadrupole mass selective detector through a direct interface. The overall design of
this system makes it feasible to collect and analyze VOCs without the requirement for a cryogen,
such as liquid nitrogen. This system was evaluated in two ways to determine its performance in
VOC sample analysis using a sorbent tube sampling method.
1.	Perkin Elmer sorbent tube collection—sorbent tube used to collect sample from the manifold or
directly in an outdoor setting is desorbed on ATD 400 by using the cold trap for concentration
2.	Summa-polished canister collection—sample transferred from canister onto a sorbent tube for
subsequent analysis using ATD 400 cold trap for concentration
RESULTS AND DISCUSSION
Quality Assurance Project Han
Before we went to the field, a Quality Assurance Project Plan was written and approved by
appropriate ManTech and EPA QA and management personnel. In the plan, we set out our
objectives for the study, schedules, responsibilities of each staff member, and our overall study
design, meeting all criteria for a Class HI Project.5 The approximate overall goal for each
quantitative QA objective is given in the following tabulation. Specific target objectives were set for
each compound, based on the previous performance history of each compound on each analytical
system.
XonTech	ATD 400/Q-Mass
QA Objectives	Saturn Manifold	Canisters Sorbent Tube
Method Detection Limit	0.1 ppbv 0.5 ppbv	0.5 ppbv	0.5 ppbv
Relative Percent Difference	10%	25%	25%	25%
Internal Audit Accuracy	20%	30%	30%	N/A
Completeness	75%	75%	75%	75%
Target Compounds
The target lists of compounds for which we calibrated the GC/MS systems are given in Table 1.
We made a concerted effort to coordinate with other NARSTO awl SOS researchers to seek
common target lists as much as we could. Although we understood that the standard target list of
the Photochemical Assessment Monitoring Station (PAMS) program was undergoing reevaluation,
we used the Alphagaz Ozone Precursor 57-compound standard, as we had it available and all
systems had been characterized with this standard. We calibrated for the TO-14 target list because
of our long history of using this standard and because we could use it as a benchmark for quick field
evaluation of system performance. Because of the expressed interest in oxygenated compounds, we
3

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96-RP128.03
added an aldehyde/ketone standard to our target list. It was prepared by injecting 100 fxL of dilute
aqueous solution of selected aldehydes and ketones into an evacuated canister and was used as a
semiquantitative calibration standard. Storage stability was only marginally evaluated because of the
press of time in preparing for the study. The limited evaluation showed that the very volatile and
the heavier compounds both demonstrated low recoveries. Further work is required to develop
methods for the preparation of adequate quantitative standards for these compounds.
Audit Standard Analysis
We conducted a blind analysis on both GC/MS systems. The audit canister was shipped to the field
site by the NERL Quality Assurance Branch. The results of these analyses are given in Table 2.
The QA laboratory analyzed the canister, using a Nutech preconcentrator with Nafion dryer. The
canister had been filled from a high-pressure cylinder containing one of the series of audit standards
used in the PAMS program. As a measure of precision, we computed the percent relative
difference between replicate analyses on each system. Excellent internal precision was found for all
measurements. After all results were validated and reported, the field analysis results were
compared to the QA lab results. Both the XonTech Saturn and Perkin Elmer results were within
acceptable limits and better than the QA lab analysis results, except for the instance where the
Perkin Elmer missed the identification of 2,3-dimethylbutane.
GC Retention Time Stability-
Retention time stability is a critical issue in measuring ozone precursor compounds, as similarity in
mass spectra of the prevalent hydrocarbon compounds may cause inaccurate identification of the
VOCs. Operating two heat-generating GC/MS systems in a trailer in the summer raises the question
of GC retention time drift with variations in the trailer temperature. We suffered periodic air
conditioner freeze-up during our 10-day study. This resulted in only one delayed start of the GC, as
the trailer ambient temperature was near the GC start temperature. We were particularly concerned
about retention time stability in the operation of our system, because we employ absolute rather than
relative retention times in our identification. Despite these worries, the retention time stability of
both systems was excellent, as illustrated in Figure 1.
Data Capture
Hourly measurements were taken continuously from June 17 through 27, with the only time lost for
daily calibration checks and two power interruptions during the course of the study; samples were
taken for 191 hours out of a scheduled 200. This represents 95% data capture for the
XonTech/Saturn system. Hie Perkin Elmer system was not operated in a continuous mode, so
calculation of completeness does not easily apply. The Perkin Elmer did demonstrate a greater
sensitivity to humidity as samples taken during rain events and in the early morning showed
depressed response because of the condensation of liquid water in the sampling tube and the
previously demonstrated limited pumping capacity of the Q-Mass mass spectrometer.
Potential Manifold and Transfer Line Artifacts
Prior to the study, concern was raised by study participants about the length of the sampling
manifold (30 m) and the successful transfer from the manifold into our sampling van. This concern
was raised because of the anticipated "stickiness" of some of the heavier (Cg-CJ0) aldehydes. A
cross-linked FEP/PTFE Teflon-coated manifold was especially constructed by University Research
Glass (Carrboro, NC) for the Georgia Tech researchers. We procured a 40-ft heated PFA Teflon
transfer line (Unique Products, Inc., Hazel Park, MI) and tested it prior to installation. The line
4

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96-RP128.03
was purged with humidified scientific-grade air and the output analyzed; do artifacts were seen
above background. We also challenged the line with standard gas from our calibration manifold; no
compounds showed diminished response from passing through the transfer line. Additional testing
for artifacts has continued since June.
CONCLUSIONS
Trailer-based near-real-time measurements of VOCs related to ozone formation can be made with
high and measurable data quality. Reasonable accuracy and excellent precision were demonstrated.
Greater than 95% data capture was achieved for the 10-day study.
ACKNOWLEDGEMENTS
Although the research described in this paper has been funded wholly or in part by the United States
Environmental Protection Agency through Contracts 68-DCW3106 and 68-D5-0049 to ManTech
Environmental Technology, Inc., it has not been subjected to Agency review and therefore does not
necessarily reflect the views of the Agency, and no official endorsement should be inferred.
Mention of trade names or commercial products does not constitute endorsement or recommendation
for use.
REFERENCES
1.	E.C. Apel, J.G. Calvert, R. Zika, M.O. Rodgers, V.P. Aneja, J.F. Meagher, and W.A.
Lonneman, "Hydrocarbon measurements during the 1992 Southern Oxidants Study Atlanta
Intensive: Protocol and quality assurance," J. Air Waste Manage. Assoc.. 45(7): 521 (1995).
2.	A. Bernardo-Bricker, C. Farmer, P. Milne, D. Riemer, R. Zika, and C. Stoneking, "Validation
of speciated nonmethane hydrocarbon compound data collected during the 1992 Atlanta Intensive
as part of the Southern Oxidants Study (SOS), "J. Air Waste Manage. Assoc.. 45(8): 591
(1995).
3.	W.A. McClenny, E.H. Daughtrey, Jr., K.G, Kronmiller, J.R. Adams, and K.D. Oliver,
"Hourly measurement of VOCs by AutoGC at the New Hendersonville, TN, Southern Oxidants
Study site, June 17-27, 1995," Paper A1004, 1996 A&WMA Annual Meeting, Nashville, TN.
4.	K.D. Oliver, J.R. Adams, E.H. Daughtrey, Jr., W.A. McClenny, M.J. Yoong, M.A. Pardee,
E.B. Almasi, and N.A. Kirshen, "Technique for monitoring toxic VOCs in air: Sorbent
preconcentration, closed cycle cooler ciyofocusing, and GC-MS analysis," Environ. Sci.
Technol.. in press.
5.	U.S. Environmental Protection Agency, Preparing Perfect Project Plans: A Pocket Guide for
the Preparation of Quality Assurance Project Plans. EPA/600/9-89/087, Available from Guy F.
Simes, Quality Assurance Manager, U.S. Environmental Protection Agency, Risk Reduction
Engineering Laboratory, Cincinnati, OH, 1989.
5

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96-RP128.03
D.A. Brymer, L.D. Ogle, C.J. Jones, and D.L. Lewis, "Viability of using Summa polished
canister for the collection and storage of parts per billion by volume level volatile organics,
Environ. Sci. Technol.. 30(1): 188 (1996).

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Table 1. Target Compounds for Nashville 1995 Summer Study.
Ozone Precursors (Alphagaz Standard)
Isobutane
I -Butene
n-Butane
frans-2-Butene
rij-2-Butene
3-Methyl-l-butenc
Isopentane
1 -Pentene
n-Pentane
Isoprene
mrnj-2-Pentene
ris-2-Pentene
2-Methyl-2-butene
2.2-Dimethylbutane
Cyclopcntenc
4-Methyl-l-pentene
2.3-DimethyIbutane
Cyclopentane
2-Methylpentane
3-Methylpentane
2-Me(hyI-1 -pentene
n-Hexane
franj-2-Hexene
a'j-2-Hcxcne
2-4-Dimethylpentant
Methylcyclopentane
Benzene
Cyclohexane
2-Methylhexane
2,3-Dimethylpentane
3-Methylhexane
2,2,4-Trimethylpentane
n-Heptane
Methylcyclohexane
2,3,4-T rimethylpentane
Toluene
2-Methylheptane
3-Methylheptane
n-Octane
Ethylbenzene
m,p-Xyfene
Styrene
©-Xylene
n-Nonane
Isopropylbenzene
cr-Pinene
n-Propylbenzcne
1,3,5-T rimethylbenzene
n-Decane
/3-Pinene
1,2,4-Trimethylbenzene
Undecane
TO-14 Standard (Alphagaz)
D ich lorod i fl uoromel h ane
Chloromelhane
1,2-Dichloro-1,1,2,2-tetrafluoroethane
Chloroethene
Bromomethane
Chloroelhane
Trichlorofluoromethane
1,1-Dichloroethene
Dichloromethane
3-ChIoropropene
1,1,2-Trichloro-1,2,2-trifluoroethane
1.1-Dichloroe»hane
as-1,2-DichIoroethene
Trichloromethane
1.2-Dichloroethane
1,1,1 -Trichloroethane
Benzene
Carbon tetrachloride
1,2-Dichloropropane
Trichloroethene
cis-1,3-DichIoropropene
trans-1,3-Dichloropropene
1,1,2-Trichloroethane
Toluene
1,2-Dibromoethane
Tetrachloroethene
Chlorobenzene
Ethylbenzene
m,p-Xylenc
Styrene
1,1,2,2-Tetrachloroethane
o-Xylene
4-Eihyltoluene
1,3,5-Trimethylbenzene
1,2,4-Trimethylbenzene
Benzyl Chloride
m-Dichlorobenzene
p-Dichlorobenzene
o-Dichlorobenzene
1,2,4-Trichlorobenzene
Hexachlorobutadiene
"Aldehyde Standard"
Methacrolein
Methyl vinyl ketone
Butanal
1,1,1 -Trichloroethane
2-Pentanone
Pentana!
Trichloroethene
Hexanal
Tetrachloroethene
Heptanal
Benzaldehyde
Octanal
Nonanal
Decanal
8
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U1

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Table 2. Precision and Accuracy of Analysis of Field Audit Canister 01628.*
Analysis Results	Replicate Average
Compound
QA Standard



Target
Lab Found
X/S Found
PE Found
1-Butene
8.90
10.50
9.34
5.01
rranj-2-Butene
8.75
10.30
9.94
11.43
3-Methyl-l-butene
11.00
13.10
9.10
10.38
1-Pentene
10.25
11.50
10.75
11.00
Isoprene
9.55
12.00
8.55
9.84
cw-2-Pentenc
9.80
11.50
10,28
12.78
2,2-Dimethylbutane
14.45
17.90
14.85
17.44
4-Methyl-1 -pentene
13.05
14.90
13.77
15.63
2,3-Dimethylbutane
13.85
16.20
14.82
0.00
3-Methylpentane
14.05
16.60
14.94
15.46
it-Hexane
13.85
15.50
14.94
15.91
cw-2-Hexene
13.10
14.70
14.13
15.40
2,4-Dimethylpentane
16.75
18.20
16.52
17.94
Cyclohexane
14.45
16.70
15.96
14.14
2,3-Dimethylpentane
17.40
20.30
18.34
20.05
2,2,4-T rimethylpentane
20.30
23.50
20.84
22.69
Methylcyclohexane
18.80
20.20
19.01
20.35
2,3,4-Trimethylpentane
18.80
21.50
20.12
20.13
2-Methylheptane
19.95
22.80
21.68
23.57
Ethylbenzene
18.65
17.80
17.36
17.34
m.p-Xylene
18.70
17.80
17.60
16.75
o-Xylene
18.15
18.50
18.16
17,97
Isopropylbenzene
19.95
20.50
20.16
20.27
1,3,5-T rimethy lbenzene
18.75
19.20
20.30
18.34
•Abbreviations: X/S * XonTech Saturn, PE = Perkin Elmer, ~~Precision = (a - b) x 2/(a + b)
Precision (%)**	Accuracy (%)***
X/S
PE
QA Lab
X/S
PE
2.68
-41.79
117
104
56
1.11
-1.50
117
113
130
-0.55
-3.32
119
82
94
0.70
-6.00
112
104
107
1.75
-2.59
125
89
103
-0.12
2.03
117
104
130
0.10
-2.16
123
102
120
-1.20
1.77
114
105
119
1.82
ERR
116
107
0
0.00
-1.19
118
106
110
0.60
1.19
111
107
114
0.74
-2.24
112
107
117
0.64
0.47
108
98
107
1.32
0.62
115
110
97
0.76
0.33
116
105
115
0.10
-0.46
115
102
111
-0.09
2.17
107
101
108
1.89
-0.93
114
107
107
1.29
-0.86
114
108
118
2.30
0.27
95
93
92
3.64
0.53
95
94
89
1.98
-0.06
101
100
99
1.56
0.55
102
101
101
2.99
0.09
102
108
97
~~~Accuracy = Found x 100%/"True\

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96-RP128.03
Oi tlier due to late: start
30.9	31	31.1
Decanal Retention Time, min
31.2
Figure 1. Typical Retention Time Stability for 10-Day Study.
9

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J TECHNICAL REPORT DATA
	
1. REPORT NO.
EPA/600/A-96/071
2.
3.REC3
4. TITLE WTO SUBTITLE
Interpretation of Data Quality Evaluation of Hourly-
Measurement of Target VOCs by AutoGC/MS at the New
Henedersonville, TN Southern Oxidants Study Site
S. REPORT DATE
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
W.A. McClenny; USEPA & E,H. Daughtrey, Jr., J.R. Adams
C.R. Fortune, K.G. Kronmiller, and K.D. Oliver;
Mantech
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Mantech Environmental
Research Triangle Park, NC
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-DO- 01OS
12. SPONSORING AGENCY NAME AND ADDRESS
US Environmental Protection Agency
Research Triangle Park, NC 27711
13.TYPE OF REPORT AND PERIOD COVERED
publication of proceedings
14 . SPONSORING AGENCY CODS
EPA/600/09
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The North American Research Strategy for Tropospheric Ozone (NARSTO) program has
sponsored the development and evaluation of monitoring methods for volatile organic
compounds (VOCs) that are associated with the formation of tropospheric ozone. Target
VOC lists have been developed that are designed to be reflective of the VOCs of concern
in ozone formation. These lists are evolving as understanding of the processes
develop. Our samples were analyzed for a target list that included the 57 ozone
precursor compounds, the 41- compound TO-14 list, and 10 selected aldehydes. Two field-
deployed autoGC systems were deployed at the New Hendersonville, TN, site which was one
of the intensive measurement sites of the 1995 Southern Oxidants study. This site
approximately 15 mi northeast of Nashville, was selected to be a downwind site,
although, ae data in a companion paper demonstrated, this was rarely the case for the
June 17-27 period that we made measurements. In this paper, quality assurance issues
related to the calibration, sampling integrity and artifacts are discussed, and
quantitative measures of data quality are described. Canister and sorbent tube samples
were also taken concurrently with some of the hourly measurements, and the concurrent
measurements are compared in this paper.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b.IDENTIFIERS/ OPEN ENDED
TERMS
c.COSATI



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