United States
Environmental Protection
Agency
Environmental Research
Laboratory
Athens, GA 30613-7799
Research and Development
EPA/600/S4-90/002 May 1990
&EPA Project Summary
Muitispectral Identification and
Confirmation of Organic
Compounds in Wastewater
Extracts
John M. McGuire, Timothy W. Collette, Alfred D. Thruston, Jr.,
Susan D. Richardson, and William D. Payne
Application of multlspectral ident-
ification techniques to samples from
industrial and POTW wastewaters
revealed identities of 63 compounds
that had not been identified by
empirical matching of mass spectra
with spectral libraries. Twenty-five of
the compounds have not been found
in wastewaters previously. Multi-
spectral techniques used in the
identifications were GC/MS (low
resolution), high resolution mass
spectrometry (HRMS), positive
methane chemical ionization mass
spectrometry (CIMS), and gas
chromatography combined with
Fourier transform infrared spectros-
COpy (GC/FT-IR).
Some of the same techniques were
used to confirm (without obtaining a
pure sample of the tentatively
identified compound) identifications
made by reexamlnation of GC/MS
data tapes generated by contractor
laboratories. Eighty percent of the
Identifications were confirmed. Some
of the wrong identifications made by
reexamination of tapes were
attributed to poor chromatography
during the initial analysis.
This Project Summary was
developed by SPA's Environmental
Research Laboratory, Athens, GA, 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).
Background
Gas chromatography/mass spectro-
metry (GC/MS) was determined in the
early 1970s to be the method of choice
for analysis of organic pollutants in water.
In support of the 1976 Consent Decree
between the U.S. Environmental Pro-
tection Agency (EPA) -and the National
Resources Defense Council, magnetic
tapes of GC/MS analyses of samples
acquired by contract laboratories for the
Industrial Technology Division (ITD) of
EPA's Office of Water were processed
through a suite of computer programs
designed to Identify both priority and
non-priority pollutants. The programs
originally had been developed for
minicomputers and had been applied in
the late 1970s and early 1980s to data
acquired in the late 1970s. These
programs were converted in 1986 and
1987 to operate on the Athens
Environmental Research Laboratory's
VAX-785 computer and were applied to
data acquired by ITD contract
faboratories during the early 1980s,
Tentative identifications were made by
computerized spectra matching from the
input data, using historical GC relative
retention times and a collection of
110,000 reference mass spectra.
Few identifications of non-priority
pollutants or confirmations of tentative
computer identifications had been made
from the 1970s data. This was attributed
both to the use of packed GC columns
and to the limited size of the reference
database (34,000 mass spectra). In the
most recent tape study, the database was
nearly three times the size of the one
used earlier, and the GC/MSv data had
been collected using capillary GC column
and protocols similar to those of EPA
Methods 625 and 1625. As had been
anticipated, the number of sample
components recognized by the computer
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increased as a result of the use of
capillary columns. Not anticipated was
the fact that the programs designed to
select the best spectrum for packed GC
columns were less effective in selecting
the best spectrum from a capillary GC
column. In particular, it was determined
that when the peak recognition algorithm
was tuned to recognize trace level
chromatographic peaks, it was quite apt
to ignore high level peaks due to the
width of the GC peak.
Sample and Compound
Selection
To check the accuracy of the tentative
identifications, as well as to determine
the identity of compounds not identified
by the tape programs, compounds from~
GO/MS runs of 19 publicly owned
treatment works and of 13 organic
chemical plants were selected as
"targets" for our reanalysis.
The analytical targets were organized
by sample source into five groups. As a
result, it is possible that a given target
might occur in a publicly owned
treatment works sample, but be a
confirmation or identification target only
in a specific organic chemical plant
study. The majority of the peaks in most
chromatograms are due to the
isotopically enriched compounds that
were used for mass spectrometric
quantitation of specific analytes by
isotope dilution.
New GC/MS chromatograms and,
where appropriate, GC/Fourier Transform
Infrared Spectroscopy (GC/FT-IR)
chromatogram^ jwere obtained for
retained^e^tratts^arid were "cbrffparW
with one another and with the
corresponding chromatograms from the
contract laboratory data. Based on these
comparisons, , sample similarities were
recognized that permitted choosing 11
representative sample extracts for the
confirmations and identifications.
Multispectral analysis of these extracts,
consisting of GC separation followed by
appropriate combinations of low and high
resolution electron impact or chemical
ionization mass spectrometry and FT-IR,
resulted in 48 confirmations, 63
identifications, and recognition of 12
common compounds that should have
been identified in the tape study. The
number of compounds identified by the
tape study could have been increased by
the following: a strict adherence to the
1625 GC protocol, a reduction in the
number of internal standards added to
T the
peak recognition algorithm used by the
tape study.
John M. McGulre (also the EPA Project Officer, see below), Timothy W. Collette,
Alfred D. Thruston, Jr., and Susan D. Richardson, are with the
Environmental Research Laboratory, Athens, GA 30613-7799. William D.
Payne is with Technology Applications Inc., Athens, GA 30613-7799.
ThB complete report, entitled "Multispectral Identification and Confirmation of
Organic Compounds in Wastewater Extracts," (Order No. PB-90 160
995/AS; Cost: $31.00, 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 Research Laboratory
U.S. Environmental Protection Agency
Athens, GA 30613-7799
United States
Environmental Protection
Agoncy
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use S300
EPA/600/S4-90/002
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