Detection and quantification of steroids produced by microbial fermentation of sterols by means of MIKE spectrometry and selected Metastable Ion Monitoring

Abstract

Several steroids generated by microbial fermentation of cholesterol were identified by the mass analysed ion kinetic energy (MIKE) spectra of their molecular ions generated under electron impact, and quantified by selected metastable ion monitoring. These analyses were performed on a crude solvent extract without any purification or molecular separation procedures. The detection limit was below the nanogram range. Identification and quantification of the major constituents, namely androst-4-ene-3,17-dione and androsta-1,4-diene-3,17-dione were fast and easy. Pregnenolone and progesterone which were present at a much lower level were identified with more difficulty by their MIKE spectra alone, because of the existence of isobaric interfering ions. Nevertheless, their quantification by single or dual metastable monitoring was possible.

Antineoplastic Agents from Higher Plants: Application of Tandem Mass Spectrometry to Xanthones from Psorospermum febrifugum

“…Compounds such as alkaloids in plant extracts (11) or carboxylic acids generated from oxidative degradation of coal ( 12) can be selectively ionized from mixtures, thus simplifying the task of characterization. Previous work on the application of ms/ ms to neutral constituents of natural products has revealed this to be more demanding than characterization of highly polar compounds (13,14).…”