NOVEL PERFLUOROACYL DERIVATIVES OF CORTICOSTEROIDS AND RELATED SUBSTANCES FOR POTENTIAL USE IN QUANTITATIVE GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

We investigated the potential of perfluoroacylation for gas chromatogr aphic mass spectro-metric determination of corticosteroids and related substances. Structure elucidation of the reaction products was perfor med with high and low resolution mass spectrometry and with proton and carbon nuclear magnetic resonance spectrometry. Besides the well know n S-enol ester formation, 17 beta-methyl-18-nor-13(14)-ene steroids we re formed via loss of the 17-alpha hydroxyl group followed by a Wagner -Meerwein rearrangement. Compounds that bear an 11 beta-hydroxy group formed additionally a 9(11) double bond when acetone was used as solve nt, whereas acetonitrile or cyclohexane led to formation of 11 beta-pe rfluoroacyl esters. In particular, perfluoroacylation of cortisol led to a clearly defined product instead of complex mixtures observed befo re, which thus makes it a valuable alternative to methoxime formation- silylation of cortisol for quantitative gas chromatographic mass spect rometric analyses.