Fig. 3.

Simultaneous quantitation of 11-deoxycorticosterone (11-DOC), testosterone, and 17-hydroxyprogesterone (17OH-Prog) by LC-MS/MS. a Chromatogram showing tracked MRMs for the three analytes. Note that 11-DOC and 17OH-Prog are isobaric and use identical MRMs; however, chromatography separation allows individual quantitation. In addition, T and 17OH-Prog overlap chromatographically, but the different MRMs allows individual quantitation. b Mass spectrum of 17OH-Prog, showing small molecular ion (331.0, [M + H]⁺) and fragments, with the 108.9 (109) amu fragment as base peak used for quantitation