United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S7-86/045 Mar. 1987
SEPA Project Summary
Simplified Volatile
Organics Sampler
Ruby H. James, Martha L Bryant,
Robert E. Adams, and Herbert C. Miller
The volatile organic sampling train
(VOST) was originally designed to
sample very low levels of volatile
materials in incinerator effluents.
Sampling systems are needed to sup-
port hazardous-waste engineering pro-
jects that require many semiroutine
sampling tests. This study provided a
design for a simplified sampling system
for medium levels of volatile organic
compounds (VOCs).
Most of this study has involved the
evaluation of sorbents and mixed
sorbent sampling tubes for a rugged,
compact VOC collection system. This
report describes the evaluation of
sorbent materials, the development of
a sampling tube, and the laboratory
evaluation of the sampling system of a
single tandem-bed sorbent tube con-
taining Tenax GC and Spherocarb
sorbents. Direct thermal desorption into
a GC/FID or GC/MS provided a rugged
and simple sampling and analysis
system.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that Is fully docu-
mented in a separate report of the same
title (see Project Report ordering in-
formation at back).
Introduction
The results of trial burns of hazardous-
waste incinerators suggest that volatile
principal organic hazardous constituents
(POHCs) and volatile products of in-
complete combustion (PICs) may be im-
portant components in incinerator
effluents. The collection and determina-
tion of VOCs boiling at less than 100 °C
has been achieved by using bags, bulbs,
and the volatile organic sampling train
(VOST). A methods manual provides in-
formation on these methods. A protocol
for the VOST has been developed which
allows the sampling and analysis of
POHCs with sufficient sensitivity to cal-
culate a ORE of equal to or greater than
99.99% when the POHCs are present in
the waste feed at 100 micrograms/g or
higher. The VOST thus provides increased
sensitivity to low-level concentrations of
volatile POHCs because of its ability to
concentrate the gaseous effluent.
This study provides the foundation for
a simplified sampling-and-analysis sys-
tem for medium concentration levels of
VOCs. Sorbent systems were examined
that would reduce the number of sorbent
tubes and the complexity of the sampling
system. Also examined were desorption
methods that would eliminate the need
for purge-and-trap (PAT) desorption of
sorbent tubes. The objective was to pro-
vide sensitivity sufficient to permit cal-
culating a ORE equal to or greater than
99.99% when POHCs are present in the
waste feed at 1000 micrograms/g or
higher.
Experimental
Selection of Solid Sorbents
After reviewing the literature, five
sorbents were selected that had been
used successfully in sampling and were
prime candidates for use in semi-routine
sampling to support engineering projects.
Five sorbents were screened (Tenax-GC,
Spherocarb, Ambersorb XE-340 and
-347, and Carbosieve G) using 3.8 cm of
the sorbent material in 3- and 8-mm-OD
sampling tubes. In the final sorbent-tube
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design, tandem-bed sorbents were used
in the sampling tubes.
Evaluation of Solid Sorbents
The five sorbents were screened by
spiking prepared tubes with 4 microliters
of a working standard solution. This re-
sulted in the following amounts of each
compound on the tubes: tetrahydrofuran,
350 ng; toluene, 347 ng; and chloro-
benzene, 442 ng. Charcoal-filtered air
was pulled through the tubes at 0.28
L/min for 3-mm tubes and 0.5 L/min for
8-mm tubes to simulate sampling of
standard atmospheres. Each tube was
thermally desorbed and analyzed by
GC/FID to determine the recovery of
VOCs from the sorbent when compared
with direct injections of the standard
solution in a GC.
Prepared sorbent tubes were used to
collect VOCs from an audit cylinder pro-
vided by EPA. The cylinder contained low
concentrations of vinyl chloride, chloro-
form, carbon tetrachloride, benzene, and
perchloroethylene in nitrogen. From the
audit cylinder, 2.5, 5, and 10 L were
sampled at 0.5 L/min. The sorbent tubes
were then thermally desorbed and
analyzed using GC/FID and GC/MS.
Concentrations were determined by com-
paring area responses of the audit
cylinder samples to area responses ob-
tained from calibration standards of
VOCs. Calibration curves were prepared
by spiking 2, 4, 6, and 8 microliters of a
standard solution (containing 294 micro-
liters/mL chloroform, 317 micrograms/
mL carbon tetrachloride, 175 micro-
grams/mL benzene, and 325 micro-
grams/mL perchloroethylene in carbon
disulfide) on sorbent tubes. The sorbent
tubes were thermally desorbed for
analysis.
Conclusions
The sampling system developed in this
study should be a useful addition to
existing protocols for sampling and
analyzing VOCs in incinerator effluents.
This sampler is not a replacement for
VOST but is intended to provide a simple
method of sampling for use when ex-
tremely low levels of detection for POHCs
are not required. It allows the sampling
and analysis of compounds boiling under
150 °C with adequate recoveries (45 to
102%) and detection capabilities (LOD 5
to 50 ng). The simplified sampling system
consists of a single tandem-bed sorbent
tube containing Tenax-GC and Spherocarb
sorbents. Direct thermal desorption into
a GC/FID or GC/MS provides a rugged
and simple sampling and analysis system.
R. James, M. Bryant, R. Adams, and H. Miller are with Southern Research
Institute, Birmingham. AL 35255-5305.
Larry D. Johnson is the EPA Project Officer (see below).
The complete report, entitled "Simplified Volatile Organics Sampler," (Order
No. PB 87-133 468/AS; Cost: $13.95, 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:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use S300
EPA/600/S7-86/045
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