Abstract: | It is shown that two configurational steroidal isomers, 14α-equilenin and 14β-isoequilenin, may be easily distinguished by the unimolecular mass analysed ion kinetic energy spectra of their corresponding molecular ions. Furthermore, many of the peaks in these spectra are found to be due to consecutive reactions, whereby product ions of an initial reaction are themselves reactive and can undergo further fragmentation. In each of these cases, the individual steps of the reaction sequence have been separated in the different field free regions of a reversed geometry, double focusing mass spectrometer. Isotopic labelling with 18O in the 17-position has also helped to clarify reaction sequences. |