United States
Environmental Protection
Agency
National Exposure
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-97/014
March 1997
Project Summary
Investigation of Selected
Detectors for Application on
Hydrocarbons Continuous
Emissions Monitoring Systems
Dave-Paul Dayton, Joan T. Bursey, and Stephanie B. Philipp
The development of a prototype emis-
sions monitoring instrument to provide
continuous or semi-continuous quanti-
tative measurement of total gaseous
nonmethane organic carbon (TGNMOC)
emissions from stationary sources will
provide better characterization and con-
trol of compounds listed in Title III of
the Clean Air Act Amendments of 1990.
To meet this goal a search was initi-
ated to identify detection systems for
TGNMOC that are both simple to use
and accurate for a wide range of or-
ganic compounds. The measurement
of oxygenated compounds is of par-
ticular interest since many emission
sources emit a considerable volume of
these compounds.
Detection systems were identified by
searching detector manufacturers' lit-
erature and talking with manufactur-
ers' technical personnel. Several de-
tector systems are marketed as capable
of measuring TGNMOC. In this report,
data are presented on the laboratory
evaluation of a Catalyzed Flame loniza-
tion Detector, a Thermionic lonization
Detector, an Oxygen-Flame lonization
Detector, and an Elemental Analyzer
for TGNMOC measurement. Fourier
Transform Infrared Spectroscopy was
also evaluated as a candidate detector.
The primary performance requirement
was that the detectors produce equal
response for all organic compounds in
a mixture, including oxygenated com-
pounds, based on the number of car-
bon atoms in the compound. None of
the detection systems evaluated met
the primary performance goal of uni-
formly measuring organic carbon re-
gardless of the chemical structure.
Some detectors were successful for
many classes of organic compounds,
but oxygenated compounds presented
a challenge that none of the detection
systems could master.
This Project Summary was developed
by EPA's National Exposure Research
Laboratory, Research Triangle Park, NC,
to announce key findings of the re-
search project that is fully documented
in a separate report of the same title
(see Project Report ordering informa-
tion at back).
Introduction
The objective of this project was to iden-
tify an appropriate detection system for
incorporation into a prototype total gas-
eous nonmethane organic carbon
(TGNMOC) emissions monitoring instru-
ment. The accurate measurement of
TGNMOC is critical to total VOC mea-
surement required at many industrial pro-
cesses. The measurement of oxygenated
compounds is of particular interest since
many emission sources emit a consider-
able volume of these compounds. The
primary performance requirement was that
the detectors produce equal response for
all organic compounds in a mixture, in-
cluding oxygenated compounds, based on
the number of carbon atoms in the com-
pound.
Although the flame ionization detector
(FID) has been used as a universal detec-
tor for complex mixtures of organic com-
pounds, compounds containing heteroat-
oms have been shown to yield lower re-
sponse than straight chain aliphatic hy-
drocarbons1, producing an underestimate
1 Skoog, D. A. Principles of Instrumental Analysis. Third
Edition, Saunders College Publishing, New York, 1985.
p. 767.
-------
of organic carbon. The following manufac-
turers of instruments indicated in their lit-
erature that they should be successful in
determining TGNMOC including oxygen-
ated organic compounds. These instru-
ments were evaluated in this study.
The Catalytic Flame lonization Detector
(CFID) manufactured by DETector Engi-
neering and Technology, Inc, (Walnut
Creek, CA) is marketed as a detection
system that provides enhanced responses
for organic compounds containing heteroa-
toms. The Thermionic Flame lonization
Detector (TID), also manufactured by
DETector Engineering and Technology, is
marketed as an oxygen-selective detector
when operated in a nitrogen (N2) environ-
ment. The Oxygen-Flame lonization De-
tector (O-FID) manufactured by Fisons In-
struments (Danvers, MA) is marketed as
the recommended detection system of the
European Economic Community and the
U.S. Environmental Protection Agency for
analysis of oxygenated compounds in
gasoline.
The Elemental Analyzer (EA) also manu-
factured by Fisons, is marketed as a de-
tection system for simultaneous carbon,
H2, N2, and O2 determinations from solid,
liquid, or gas samples. High detection lim-
its and detection of methane and carbon
dioxide interfere with the application of
this detection system to TGNMOC mea-
surement.
A Fourier Transform Infrared (FTIR) op-
tical detection system was investigated.
The FTIR technique allows the collection
of the entire IR spectrum from about 4000
to 200 wave numbers within a few sec-
onds. The molecular signature is obtained
over a broad spectral range; accurate iden-
tification of the species can be made from
this signature. The advantage of taking
the entire IR spectrum is that if interfering
species are present they will almost cer-
tainly not be present at all of the same
frequencies, and judicious selection of
analysis regions will produce interference-
free detection.
Laboratory Procedures
The FID, CFID and TID were evaluated
with liquid standards containing the oxy-
genated and non-oxygenated compounds.
The compounds were acetaldehyde,
methanol, acetone, 2-butanone, benzene,
butyl cellosolve®, benzaldehyde, hexane,
heptane, iso-octane, nonane, methylene
chloride, and triethylamine. The FTIR spec-
trometer was evaluated using a synthetic
mixture of standards prepared in SUMMA®
canisters.
Conclusions
None of the detectors evaluated met
the performance goal of universal, linear,
organic carbon response. While some suc-
cess was realized for many classes of
organic compounds, oxygenated com-
pounds presented the strongest challenge
to the detection systems evaluated. Within
an individual chemical class, a 1:1 linear
carbon response relationship was
achieved, but a linear carbon response
relationship was not achieved when com-
paring one chemical class to another.
These detectors are useful for selective
applications, but they do not meet the
needs of an universal detector for total
carbon in a sample containing a mixture
of compounds from various chemical
classes.
Information in this document has been
funded wholly by the U.S. Environmental
Protection Agency under Contract 68-D1-
0010 to Eastern Research Group. It has
been subjected to Agency review and ap-
proved for publication. Mention of trade
names or commercial products does not
constitute endorsement or recommenda-
tion for use.
-------
Dave-Paul Dayton, Joan T. Bursey, and Stephanie B. Philipp are with Eastern Research
Group, Inc., Morrisville, NC 27526.
Merrill D. Jackson is the EPA Project Officer (see below).
The complete report, entitled "Investigation of Selected Detectors for Application on
Hydrocarbons Continuous Emissions Monitoring Systems," (Order No. PB97-
143168; Cost: $21.50, 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:
National Exposure 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 $300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT NO. G-35
EPA/600/SR-97/014
------- |