The secondary mass spectra formed by collisionally activated dissociation (CAD) of fragment ions in the mass spectra of steroids can provide specific information on molecular substructures and stereochemistry in addition to fragmentation pathways. For oxygenated steroids containing 3- and 17-substitutents, CAD reference spectra of 37 isomeric fragment ions of the compositions C2H5O, C5H8O, C5H10O, C11H15, C11H16, C11H18O, C15H21, C15H23O, C15H24O, C16F24O, and C16F26O were cataloged. For D-ring-substituted 3-hydroxy steroids, absolute assignment of the stereochemistry of both the hydroxyl group and A/B ring junction can be made from the CAD spectra of their C16H260+. ions. Applicability of tandem mass spectrometry (MS/MS) to unknown steroids is illustrated with the hypothetical structure determination of 30-hydroxy-5a-pregnan-2O-one.
ASJC Scopus subject areas
- Colloid and Surface Chemistry