Abstract
Polar derivatization method for electrospray ionization (ESI) was developed and applied to the sensitive analysis of nonpolar ketosteroid in plasma. 4-Androstene-3,17-dione (androstenedione) in human plasma was purified by solid-phase extraction with Bond Elut C18 and derivatized to the carboxymethyloxime form (androstenedioxime) as a polar derivative. Androstenedione-d6 as an internal standard was synthesized and its deuterium contents were satisfactory for the sensitive analysis of androstenedione. The LC/ESI-MS condition for androstenedioxime was performed and single peak was obtained without separation of four steric isomers. Sensitivity of androstenedioxime in this mehtod was enhanced 5 times higher than androstenedione. Calibration graphs were linear (r=0.999) from 2.5 to 100 ng/ml for androstenedione extracted from human plasma and inter-assay precision (RSD) was within 6%.
