Correlation of product ion profiles with molecular structures of androgenic and anabolic steroids in ESI MS/MS

Androgenic and anabolic steroids (AASs) are a class of chemical substances closely related to testosterone in molecular structure. They can be abused to enhance performances in human and equine athletes, and are banned by the sports authorities. To assist with method development for doping analyses of AASs, investigations were conducted to correlate their product ion profiles with the molecular structures. Although very similar in chemical structure, AASs generated noticeably different product ion profiles from collision-induced dissociation (CID). On the basis of both outlines of the product ion profiles and molecular structures, AASs studied were classified into six subclasses. In each subclass, the product ion profiles were identical or similar. However, the product ion profiles in one subclass were remarkably different from those in another. The classification reveals that the position and number of double bond(s) in conjugation with the 3-carbonyl group in the molecular structure of an AAS have significant effects on product ion profile. The presence or absence of the 19-methyl group in an AAS also has a remarkable influence on its product ion profile. A substitution in the A-, B- or D-ring of an AAS may cause a shift in mass value of the product ions. The correlation of product ion profiles with molecular structures of AASs has the implication that each AAS can be characterized by a combination of its [M + H](+) ion and product ion profile and as a result be identified with specificity. The classified product ion pattern may be useful in the identification of unknown AASs.