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 serum 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 using an automated solid-phase extraction procedure involving both a reversed-phase and normal-phase procedure on a single C-18 cartridge. The analytical chromatography was performed using a Symmetri C-8 50X2.1 mm, 3.5 mu m column. 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 operated in the positive electrospray ionisation (ESI) mode. The assay is specific, sensitive, and has a capacity of more than 100 samples per day, with a limit of quantitation of 10 pg ml(-1) for a 1.0-ml sample aliquot. It is 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.