Studies in chemical ionization mass spectrometry: 17‐hydroxy steroids

Abstract

The chemical ionization mass spectra of several hydroxy steroids were obtained using methane as the reactant gas. The spectra are much less complex than the electron ionization spectra and little fragmentation of the steroid nucleus is observed. The major fragment ions involve the loss of water from [M + HI+. A 3-keto group in the steroids was characterized by an abundant [M + C,H,]+ ion. 5a-and 5p-Dihydrotestosterone could be distinguished by their spectra, with H, as the reactant gas by marked differences in amounts of [M + HI+, [M + H -H,O]+ and [M + H -

Determination of the site of protonation of substituted benzenes in water chemical ionization mass spectrometry

“…experiments may be somewhat greater than thermal and include a significant number of ring protonated molecules. In any event, the observation that reaction (8) goes to completion shows only that the ring protonated structure is accessible in the i.c.r. experiment; it does not prove that ring protonation is energetically favored over oxygen protonation.…”

“…experiments suggest that anisole protonates on the ring, based on the observation of reaction (8), which proceeds to completion. The referee suggests that the benzene ring may (8) be the energetically favored site of protonation in anisole, but that the slight endothermicity of transferring the proton from the ring to the oxygen is more than offset by the formation of the strong hydrogen bond to water. The present experiments are not capable of unambiguously disproving this suggestion, and if correct, it would be an interesting example of 'solvation effects' shifting the favored site of protonation.…”

Strategy for structural elucidation of drugs and drug metabolites using (MS)n fragmentation in an electrospray ion trap

“…There is little systematic data available in the literature on the chemical structures of protonated drug molecules and their fragmentation in ESI‐MS. Proposals have been made regarding the fragmentation of simple molecules such as amines,8 ketones and ethers,9 monosubstituted cyclohexane derivatives,10 X‐Cn‐Y (X,Y: functional groups, Cn: Carbon skeleton)11–14 and xylene derivatives,15 often in the course of methane CI‐MS. In most cases these protonated molecules were studied using CI‐MS16 between 1970–1985, and thus before the appearance of ESI‐MS 17…”

Analysis of non-conjugated steroids in water using paper spray mass spectrometry

“…1A (iv) Most polar steroids can be readily protonated or deprotonated using PS-MS (in positive or negative ion mode). However, the degree of their protonation is also dependent on their proton affinity (with high proton affinity favoring formation of the protonated molecule) 61 . The addition of dopants can improve the analytical specificity and detection limits for certain analytes in complex mixtures 51 .…”