Studies in chemical ionization mass spectrometry:Steroidal ketones

The CH 4 chemical ionization (CI) spectra of several keto‐steroids are reported as well as the H 2 and C 3 H 8 CI spectra of a few keto‐steroids. [M + H  H 2 O] + is an abundant ion in the CH 4 CI spectrum of 5α‐androstane‐17‐one and the water loss from the [M + H] + ions does not involve the hydrogens on C‐18 and only involves the C‐16 hydrogens to about 10%. The major loss process has not been determined.3‐Keto and 17‐Keto steroids are readily distinguished by their CH 4 CI spectra. The effectiveness of substituents for directing attack by [CH 5 ] + and [C 2 H 5 ] + can be estimated:carboxyl > methoxy ≃ carbonyl > bromo ≃ chloro > hydroxy. Significant differences are observed in the H 2 CI spectra of two 5α‐vs. 5β‐steroids. Propane CI Spectra are similar to methane CI spectra, but show generally less fragmentation.