ISSN:
0306-042X
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A means of recognition of functional groups in organic molecules using chemical ionization mass spectrometry is described. Mass spectra of 34 C27-steroids using methane, isobutane and ammonia as reagent gases are recorded and correlations with structure proposed. Ammonia chemical ionization spectra are most instructive, generally yielding abundant ions of four types: an ammonium adduct [M+ NH4]+, an ammonia displacement ion [M + NH3 - X]+, a protonated molecular ion [M + H]+ and an elimination ion [M - X]+. Both the [M + H]+ and [M - X]+ ions appear to derive from the ammonium adduct [M + NH4]+, and the ion [M + NH3 - X]+ derives by a nucleophilic displacement of an elimination fragment X by neutral ammonia. Steroid ketones and olefins give predominantly [M + NH4]+ and [M + H]+ ions, whereas alcohols and esters give a three-component pattern of [M + NH4]+, [M + NH3 - X]+ and [M - X]+ ions. Spectra derived using methane or isobutane as reagent gas contain three major ion types: the protonated molecular ion [M + H]+, the hydride abstraction ion [M - H]+ and the elimination ion [M - X]+. Steroid ketones give the [M + H]+ion predominantly; the olefins give both [M + H]+ and [M - X]+ ions. Steroid alcohols give [M + H]+, [M - X]- ions. Recognition by these means of functionality in nonsteroid compounds appears also to be possible.
Additional Material:
3 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bms.1200051103
