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RAPID AND ACCURATE METHOD FOR ESTIMATING MOLECULAR WEIGHTS OF ORGANIC COMPOUNDS FROM LOW RESOLUTION MASS SPECTRA
Citation:
Scott, D. RAPID AND ACCURATE METHOD FOR ESTIMATING MOLECULAR WEIGHTS OF ORGANIC COMPOUNDS FROM LOW RESOLUTION MASS SPECTRA. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-93/317 (NTIS PB93229383).
Description:
An improved method of estimating molecular weights of volatile organic compounds from their mass spectra has been developed and evaluated for accuracy. his technique can be implemented with a user friendly expert system on a personal computer. he method is based on a pattern recognition based classifier and empirically derived rules from a set of toxic and related organic compounds. he set of compounds consists of six classes: nonhalobenzenes; chlorobenzenes; bromoand bromochloroalkanes/alkenes; mono- and dischloroalkanes/alkenes; tri, tetra- and pentachloroalkanes/alkenes; and unknowns. n the present study improvements for the unknown class, which is the largest class in actual samples, were made. or this latter class new rules were derived using a new feature of the mass spectrum. xtensive testing of the system was conducted with reference and field data. he probable errors in the estimated molecular weight were 0.5 daltons for training reference spectra and 5.0 and 1.3 daltons for randomly selected and field spectra, respectively. hese errors are about one-half those of previous versions of the system. he test results show that the domain of validity of this present system greatly exceeds the original training domain.