Solid- and Liquid-phase extraction for the gas chromatographic-tandem massspectrometric quantification of 2,3-dinor-thromboxane B-2 and 2,3-dinor-6-oxo-prostaglandin F-1 alpha in human urine

Whole body synthesis of thromboxane A(2) is best assessed by quantifying no n-invasively its major urinary metabolite, i.e., 2,3-dinor-thromboxane B-2 (2,3-dn-TxB(2)), by gas chromatography-mass spectrometry (GC-MS) or GC-tand em MS. Methods based on these techniques usually require a series of extrac tion and purification procedures including solid-phase extraction (SPE) and thin-layer chromatography (TLC) or liquid chromatographic separation of au thentic or derivatized 2,3-dn-TxB(2). Taking advantage of the inherent accu racy of GC-tandem MS and the high selectivity of the extraction of methoxim ated 2,3-dn-TxB(2) on phenylboronic acid SPE cartridges we developed a meth od that involves only SPE steps prior to quantification by GC-tandem MS. Th e method was validated by performing in Parallel an additional TLC step. Me thod mean accuracy and precision were of the order of 103% and 95%, respect ively. The method allows furthermore co-processing of the same urine sample to quantify accurately and rapidly the major urinary metabolite of prostac yclin, i.e., 2,3-dn-6-oxo-prostaglandin (PG) F-1 alpha, by GC-tandem MS. Th e limit of detection of the method was below each 5 pg of 2,3-dn-TxB(2) and 2,3-dn-6-oxo-PGF(1 alpha) per 5 ml of urine. Our study suggests that diner metabolites of isothromboxanes and isoprostacyclins are not abundantly pre sent in human urine. (C) 2000 Elsevier Science B.V. All rights reserved.