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RECORD NUMBER: 2 OF 4

OLS Field Name OLS Field Data
Main Title Probabilities of Peak Occurrence and Information Content of the NBS/EPA/MSDC Mass-Spectral Data Base.
Author Scott, D. R. ;
CORP Author Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab.
Publisher c1989
Year Published 1989
Report Number EPA/600/J-89/314;
Stock Number PB90-200676
Additional Subjects Mass spectroscopy ; Chemical analysis ; Reference groups ; Chlorohydrocarbons ; Tables(Data) ; Bromohydrocarbons ; Molecular weight ; Probability theory ; Reprints ; Databases ; Volatile organic compounds
Holdings
Library Call Number Additional Info Location Last
Modified
Checkout
Status
NTIS  PB90-200676 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. 08/27/1990
Collation 18p
Abstract
The probabilities of peak occurrence and binary information contents were calculated for the 43990 mass spectra in the 1987 NBS/EPA/MSDC database. The median molecular weight of compounds in the database was 230. Compounds composed of combinations of C, H, N, and O comprised 64% of the spectra. The number of base peaks per mass channel was also tabulated. A 30480 spectra subset of compounds with low molecular weights was selected as a volatile compound database. The median molecular weight of the group was 189. The probabilities and information contents of the set of spectra and the volatile hydrocarbons, oxygenated hydrocarbons, chloro compounds, and bromohydrocarbons were calculated. The most common peak in the entire database and in the volatile set occurred at mass 41. All peaks in both of these sets of spectra with probabilities greater than 0.50 occurred below mass 78. The probabilities over the total and volatile database showed a general decrease with increasing mass channel with a division into odd and even mass curves which converged at high masses. Mass channels with 0.90 to 1.0 bit information content occurred below ca. mass 100. Information contents decreased with increasing mass and the two odd and even mass curves were superimposed on the general trend.