Simultaneous determination of prostaglandin E1, prostaglandin E0 and 15-keto-prostaglandin E0 in human plasma by gas chromatography/negative-ion chemical-ionization tandem mass spectrometry

A sensitive and selective routine method for the simultaneous determination of prostaglandin E-1 (PGE(1)), prostaglandin E-0 (PGE(0)) and 15-keto-prostaglandin E-0 (15-keto-PGE(0)) in human plasma is described using deuterated internal standards. The analytes were isolated from acidified human plasma by solid-phase extraction by means of Bond Elut C-18 cartridges and derivatized to the pentafluorobenzyl (PFB) ester methoxime. The analytes were purified on Bond Elut Si cartridges and converted to the trimethylsilyl (TMS) ether. Quantitation was achieved by gas chromatography-negative-ion chemical-ionization tandem mass spectrometry. The precursor ion [M-PFB](-) = [P](-) carried more than 80% of the total ion current. Collision activated decomposition (CAD) of [P](-) resulted in characteristic product ions of which the [P-2(CH3)(3)SiOH](-) ion (PGE(1)) and the [P-(CH3)(3)SiOH](-) ion (PGE(0) and 15-keto-PGE(0)) were used for quantitation. The lower limit of quantitation (LLQ) was 2 pg/ml (PGE(1) and PGE(0)) and 10 pg/ml (15-keto-PGE(0)) extracted from 2 ml of human plasma. Linear calibration curves were obtained over the concentration range 2-100 pg/ml (PGE(1) and PGE(0)) and 10-500 pg/ml (15-keto-PGE(0)). In ail cases, the precision and accuracy were <17%. The present method has been applied successfully to pharmacokinetic and clinical studies in humans. (C) 1999 Elsevier Science BN. All rights reserved.