United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Las Vegas, NV 89193-3478
Research and Development
EPA/600/S4-90/008 May 1990
SEPA Project Summary
Field Demonstration for Mobile
FT-IR for Detection of Volatile
Organic Chemicals
William G. Fateley, Robert M. Hammaker, and Donald F. Gurka
A mobile laboratory is now
available to measure toxic
compounds in the atmosphere. The
mobility of this unit allows access to
many sites in the continental United
States. When this laboratory arrives
at a designated site, a high resolution
Fourier transform infrared (FT-IR)
instrument is used to measure the
toxic materials, or volatile organic
compounds, in the atmosphere. The
site could be a landfill, lagoon,
industrial site, chemical spill or any
area where atmospheric pollution
occurs. The FT-IR instrument is
capable of identifying and quantifying
atmospheric molecules at the parts
per billion (ppb) level. The path
observed by this instrument could be
as small as a few meters, or as large
as 600 meters in length, nearly 2,000
feet. Recently, the chemicals emitted
at an industrial site have been
identified at distances of up to 0.3
mile.
This Project Summary was
developed by EPA's Environmental
Monitoring Systems Laboratory, Las
Vegas, NV, to announce key findings
of the research project that is fully
documented in a separate report of
the same title (see Project Report
ordering information at back).
Discussion
The measurement of toxic compounds
in the atmosphere is simplified by the
fact that each compound has a specific
spectral "fingerprint." The identification
of the various "fingerprints," or com-
pounds, can be routine by FT-IR. The
measurement can be made on the site,
or, should the situation necessitate it, at a
reasonable distance downwind from the
site.
The sensitivity and selectivity of FT-IR
methods for volatile organics is excellent
for low resolution spectroscopy and is
fully expected to be so for high
resolution. However, the speed and
economics relative to conventional air-
toxic methods merits further scrutiny, and
Table 1 compares the analysis time of
the two techniques. In addition to the
advantage of producing near real-time
data, a major advantage of the long-path
FT-IR approach over point sample
collection/analysis techniques is the cost
effectiveness. Most air pathway analyses
(APA) at Superfund sites use the point
sampling approach in spite of the
dynamic nature of air masses. Many
samples are collected and analyzed to
compensate for this temporal variability
but not without a considerable expendi-
ture of time and money ($500-
1000/sample).
This study has demonstrated that this
FT-IR system can be used to detect toxic
compounds in the atmosphere over a
Superfund site. Within a matter of hours
after the van arrives on a site, qualitative
and quantitative information on toxic
atmospheric compounds can be
available. From this information one can
make recommendations for additional
monitoring studies, removal or remedial
action, and determine if pre-established
safety levels are being exceeded. This
mobile laboratory enhances the capability
of present and future site assessment.
Performance of the spectrometer is
presented in Table 2. The table provides
wave numbers of peaks used for
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Table 1. Comparison of Analysis Times per Canister and for Open-Path Infrared Methods3
Sample Collection Cryofocus Minimum-Maximum
Time, Desorption, Instrument Time, Time,
Hrs Mins Mins Wins
Canister
FT-IR
0-24*>
0
10-30
0
45
5-60°
25-80
5-60
0 Multiple canister analyses are required to profile a field site.
b To completely fill canister. Zero indicates almost instantaneous sample collection.
° Dependent on ambient pollutant concentrations, spectral complexity, and operator skill.
identification and quantitative determina-
tion of volatile organics, the spectral
resolution obtained in the transformed
spectra, and the detection limit for most
compounds at a path length of 100
meters. The compounds include a variety
of purgable halogen containing
compounds and purgable aromatics
measured by current EPA methods, as
well as non-purgables (e.g., n-butanol,
1,4-dioxane and ethyl acetate) not
amenable to standard methods.
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Table 2. Estimated Detection Limits (ppb) for Some Volatile Organic Compounds (VOCs) at
a Path Length of 100 Meters Using an Appropriate Absorption Band from the Mid-
Infrared Region
Compound
Chlorinated hydrocarbons
Allyl chloride
Carbon tetrachloride
Chlorobenzene
Chloroform
1 ,2-Dichloroethane
Methylene chloride
Tetrachloroethylene
1,1,1 -Trichloroethane
Trichloroethylene
.Arornatic hydrocarbons
Benzene
Ethylbenzene
Pyridine
Toluene
Alkane
Cyclopentane
Alcohols
n-Butanol
Ethanol
Isopropanol
Methanol
Ketones
Acetone
Methyl ethyl ketone
Methyl isobytyl ketone
Wavenumber
(cnr1)
756.9
795.2
741.2
772.6
731.3
749.5
916.3
726.3
849.4
673.9
2794.0
700.3
694.3
2966.0
2967.4
7068.8
7066.7
2982.7
956.5
7033.4
7033.4
7277.7
7774.2
2965.4
Resolution
(cm-1)
0.5
0.5
0.1
0.5
0.5
0.5
0.5
0.5
0.5
0.1
0.5
0.1
0.1
0.5
0.5
0.5
0.5
0.5
0.5
0.1
0.5
0.5
0.5
0.5
Detection Limit
(Ppb)a
67
6.3
26
b
34
20
19
8.1
18
c
37
c
c
7.2
22.4
35
37
79
76
78
8.7
36
40
78
£sfer
Ethyl acetate
Ethers
1241.4
0.5
5.0
Diethyl ether
1,4-Dioxane
Tetrahydrofuran
1142.9
2863.1
1138.3
2981.7
7084.4
0.5
0.5
0.5
0.5
0.5
9.3
77
9.9
77
26
a These detection limits, using concentration in parts per billion (ppb), are for P = 740 torr and
T = 298 K.
b These measurements are being repeated.
0 These bands fall in spectral regions containing sharp water vapor absorption bands, and the detection
limits are dependent on humidity.
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William G. Fateley and Robert M, Hammaker are with Kansas State University,
Manhattan, KS 66506. Donald F. Gurka (also the EPA Project Officer, see
below) is with Environmental Monitoring Systems Laboratory, Las Vegas,
NV 89193-3478.
Tha complete report, entitled "Field Demonstration for Mobile FT-IR for
Detection of Volatile Organic Chemicals," (Order No. PB 90-192 014/AS;
Cost: $23.00, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Las Vegas, NV 89193-3478
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S4-90/008
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