One-Step Solid-Phase Extraction Procedure for F2-Isoprostanes

Abstract

F2-isoprostanes (F2-iPs) are a group of prostaglandin-like isomers produced from peroxidized arachidonic acid (AA)-containing phospholipids (1). They are new and important markers of lipid peroxidation in vivo <(1). However, their introduction into clinical practice has been limited by the need to extract the compounds from their biologic matrices before analysis by immunologic methods or mass spectrometry. Morrow et al. (2) and others (3)(4) used multiple steps, including thin-layer chromatography and HPLC, in their purification methods. Apart from being time-consuming, these procedures also led to substantial losses of the target compound. In one study (5), the recovery of a urinary metabolite of iPF2α-III was only 20–30%. Recently, Nourooz-Zadeh et al. (3), using a reversed-phase C18 cartridge followed by a normal-phase NH2 cartridge, reported a recovery of 75% for F2-iPs (6). However, this procedure is still time-consuming. In this report, we present a simplified and rapid procedure for extracting F2-iPs from biologic samples using an Oasis HLB extraction cartridge (Waters Corporation). This cartridge contains a unique copolymer sorbent with hydrophilic and lipophilic groups in proportions that allow high and reproducible recoveries of acidic, basic, and neutral compounds, whether polar or nonpolar (7). To study the performance of the Oasis cartridge, we prepared two F2-iP samples. The first sample contained F2-iPs isomers generated …