Identification of individual steroids in biological matrices by mass-analyzed ion kinetic energy spectrometry

Individual steroids can be distinguished by their mass-analyzed ion kinetic energy (MIKE) spectra. These spectra are taken for the protonated compounds generated by chemical ionization and they yield characteristic fragmentation patterns for different steroids. Isomeric steroids can be differentiated by their MIKE spectra. In some cases this can also be achieved by examining a single ionic reaction rather than the entire spectrum. For example, protonated dehydroepiandrosterone undergoes spontaneous elimination of water while its isomer, testosterone undergoes this reaction with a lower cross-section and then only when excited by collision with target gas. Mixtures of steroids can be analyzed qualitatively. This is illustrated by the analysis of birth control pills (Ovral) for ethynylestradiol and norgestrol. Analysis of urine specimens for particular steroids without pretreatment or preconcentration is possible in some cases.