Electrospray collision-induced dissociation of testosterone and testosterone hydroxy analogs

Complications with the gas chromatographic analysis of steroids prompted th e use of alternative techniques for their identification. High-performance liquid chromatography/mass spectrometry with atmospheric pressure ionizatio n allowed the collection of data for structural identification of these com pounds. The objective of this study was to investigate the up-front collisi on-induced dissociation (UFCID) electrospray ionization (ESI) mass spectra of testosterone and monohydroxylated testosterones, The positive ion UFCID ESI mass spectrum of testosterone showed three significant ions at m/z 97, 109 and 123. The relative abundance of these ions in the UFCID ESI mass spe ctra of monohydroxylated testosterones varied with the position of the hydr oxy group. Statistical data allowed the prediction of hydroxy group positio n on testosterone by evaluation of the relative abundance of the m/z 97, 10 9, 121 and 123 ions. Data from the ESI mass spectral analysis of testostero ne in a deuterated solvent and from the analysis of cholestenone and 4-andr ostene3 beta,17 beta-diol indicated that the initial ionization of testoste rone occurred at the 3-one position, CID parent ion monitoring analyses of the m/z 97, 109 and 123 ions indicated that each resulted from different fr agmentation mechanisms and originated directly from the [M + H](+) parent i on. The elemental composition of these fragment ions is proposed based on e vidence gathered from the CID analysis of the pseudo-molecular ions of [1,2 (-2)H(2)]-, [2,2,4,6,6-H-2(5)]-, [6,7(-2)H(2)]-, [7-H-2]-, [19,19,19-H-2(3) ]- and [3,4-C-13(2)] testosterone. The structure and a possible mechanism o f formation of the mit 109 and 123 ions is presented. The results of this: study advance the understanding of the mechanisms of collision-induced frag mentation of ions. Copyright (C) 1999 John Wiley & Sons, Ltd.