Record Display for the EPA National Library Catalog


Main Title Improved Method for Estimating 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-92/133;
Stock Number PB92-166685
Additional Subjects Volatile organic compounds ; Molecular weight ; Spectrum analysis ; Mass spectroscopy ; Pattern recognition ; Expert systems ; Performance evaluation ; Air pollution ; Error analysis ; Reprints ;
Library Call Number Additional Info Location Last
NTIS  PB92-166685 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 13p
An improved method of estimating molecular weights of volatile organic compounds from their mass spectra has been developed and implemented with an expert system. The method is based on the strong correlation of MAXMASS, the highest mass with an intensity of 5% of the base peak in a mass spectrum, with the true molecular weight. Linear corrections to MAXMASS, which yield molecular weight estimates, were derived empirically using the expert system. The system is based on a sequential modular design with a primary classifier linked to molecular weight estimators for the resulting six classes. These are non-halobenzenes; chlorobenzenes; bromoalkenes/alkenes; mono- and dichloroalkanes/alkenes; tri-, tetra- and pentachloro-alkanes/alkenes; and others. Performance tests were made with the old and improved expert systems 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 27 spectra taken from actual field gas chromatography/mass spectrometry samples.