Record Display for the EPA National Library Catalog


Main Title Rapid and Accurate Method for Estimating Molecular Weights of 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 c1992
Year Published 1992
Report Number EPA/600/J-93/317;
Stock Number PB93-229383
Additional Subjects Molecular weight ; Volatile organic compounds ; Spectrum analysis ; Pattern recognition ; Expert systems ; Air pollution detection ; Computer aided analysis ; Mass spectroscopy ; Toxic substances ; Classification ; Chemical analysis ; Performance evaluation ; Halogen organic compounds ; Benzenes ;
Library Call Number Additional Info Location Last
NTIS  PB93-229383 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 12p
An improved method of estimating molecular weights of volatile organic compounds from their mass spectra has been developed and evaluated for accuracy. This technique can be implemented with a user friendly expert system on a personal computer. The method is based on a pattern recognition based classifier and empirically derived rules from a set of toxic and related organic compounds. The set of compounds consists of six classes: nonhalobenzenes; chlorobenzenes; bromo- and bromochloroalkanes/alkenes; mono- and dichloroalkanes/alkenes; tri, tetra- and pentachloroalkanes/alkenes; and unknowns. In the present study improvements for the unknown class, which is the largest class in actual samples, were made. For this latter class new rules were derived using a new feature of the mass spectrum. Extensive testing of the system was conducted with reference and field data. The probable errors in the estimated molecular weights were 0.5 daltons for training reference spectra and 5.0 and 1.3 daltons for randomly selected and field spectra, respectively. These errors are about one-half those of previous versions of the system. The test results show that the domain of validity of this present system greatly exceeds the original training domain.