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RECORD NUMBER: 36 OF 81

OLS Field Name OLS Field Data
Main Title Expert System for Estimates of Molecular Weights of Volatile Organic Compounds from Low-Resolution Mass Spectra.
Author Scott, D. R. ;
CORP Author Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab.
Publisher c1991
Year Published 1991
Report Number EPA/600/J-91/207;
Stock Number PB91-242990
Additional Subjects Mass spectroscopy ; Volatile organic compounds ; Molecular weight ; Spectrum analysis ; Pattern recognition ; Gas chromatography ; Toxic substances ; Molecular structure ; Performance evaluation ; Reprints ; Expert systems ; Reference spectra
Holdings
Library Call Number Additional Info Location Last
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Status
NTIS  PB91-242990 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. NTIS 11/26/1991
Collation 15p
Abstract
MAXMASS, the highest mass with an intensity of 5% of the base peak in a low resolution mass spectrum, has been found to be linearly correlated with the true molecular weights of 400 randomly selected spectra, yielding a family of parellel lines. A simple expert system using MAXMASS has been developed to estimate molecular weights of unknown volatile compounds from their mass spectra. This is an empirical rule-based system which will run on a personal computer. It consists of a classification module chained to separate molecular weight prediction modules for six classes. These are benzenes; chlorobenzenes; bromoalkenes/alkenes; mono- and dichloroalkanes/alkenes; tri-, tetra- and pentachloroalkanes/alkenes; and unknown (other) classes. The rules were derived from National Institute of Standards and Technology (NIST) reference spectra of 75 target toxic compounds from the first five classes and 32 from the unknown class. Performance tests of molecular weight predictions were made with the expert system and the Self Training interpretive and Retrieval System (STIRS) on NIST reference spectra of the 107 training compounds; on a set of 32 test NIST reference spectra of other compounds found in air samples; on a set of 100 randomly selected NIST reference spectra; and on 30 spectra taken from actual field gas chromatography/mass spectrometry samples. (Copyright (c) 1991 - Elsevier Science Publishers B.V.)