Determination of the vitamin D analog EB 1089 (seocalcitol) in human and pig serum using liquid chromatography-tandem mass spectrometry

A liquid chromatographic-tandem mass spectrometric assay in human and pig s erum has been developed for quantitative analysis of EB 1089 (seocalcitol). EB 1089 is a novel vitamin D analog under development for the treatment of cancer. The analyte was extracted from serum after protein precipitation u sing an automated solid-phase extraction procedure involving both a reverse d-phase and normal-phase procedure on a single C-18 cartridge. The analytic al chromatography was performed using a Symmetri C-8 50X2.1 mm, 3.5 mu m co lumn. The mobile phase was a linear gradient from 75% to 99% methanol with a constant concentration of 2 mM ammonium acetate. EB 1089 and the internal standard [d(6)]-EB 1089 were detected by using MS-MS. The ion source was o perated in the positive electrospray ionisation (ESI) mode. The assay is sp ecific, sensitive, and has a capacity of more than 100 samples per day, wit h a limit of quantitation of 10 pg ml(-1) for a 1.0-ml sample aliquot. It i s now used for routine analysis in connection with pharmacokinetic studies in humans and toxicokinetic studies in pigs, (C) 2000 Published by Elsevier Science B.V. All rights reserved.