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Methane Negative Chemical Ionization Analysis of 1,3-Dihydro-5-Phenyl-1,4-Benzodiazepin-2-Ones
W. A. Garland and B. J. Miwa
Environmental Health Perspectives
Vol. 36 (Jun., 1980), pp. 69-76
Published by: The National Institute of Environmental Health Sciences
Stable URL: http://www.jstor.org/stable/3429334
Page Count: 8
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The methane negative chemical ionization (NCI) mass spectra of the medically important 1,3-dihydro-5-phenyl-1,4-benzodiazepin-2-ones generally consisted solely of M- and ( M- H)- ions. Attempts to find the location of the H lost in the generation of the ( M- H)- ion were unsuccessful, although many possibilities were eliminated. A Hammett correlation analysis of the relative sensitivities of a series of 7-substituted benzodiazepines suggested that the initial ionization takes place at the 4,5-imine bond. For certain benzodiazepines, the ( M- H)- ion generated by methane NCI was 20 times more intense than the MH+ ion generated by methane positive chemical ionization (PCI). By using NCI, a sensitive and simple GC-MS assay for nordiazepam was developed that can quantitate this important metabolite of many of the clinically used benzodiazepines in the blood and brain of rats.
Environmental Health Perspectives © 1980 The National Institute of Environmental Health Sciences