Quantitative measurement of propofol and in main glucuroconjugate metabolites in human plasma using solid phase extraction–liquid chromatography–tandem mass spectrometry

A high-performance liquid chromatographic method coupled with tandem mass spectrometry detection has been developed for the determination of propofol and its main glucuroconjugate metabolites (propofol–glucuronide (PG), 1-quinol-glucuronide (1-QG) and 4-quinol-glucuronide (4-QG) in human plasma. All compounds were extracted with a single solid phase extraction procedure using Max Oasis© cartridges. Propofol and thymol (internal standard) were analyzed using a C8 reversed-phase column with a mobile phase consisting of methanol–water (75:25, v/v) containing 0.025% NH4OH. Chromatography of glucuroconjugate metabolites and phenyl-β-d-glucuronide (internal standard) was performed using a hydrophilic interaction liquid chromatography (HILIC) and a mixture of acetonitrile/water/ammonium acetate buffer (100 mM, pH 5, 87/1/12, v/v/v). Both chromatographic separations were achieved in isocratic mode allowing a rapid analysis without re-equilibration of the phase. The method is specific and sensitive with a range of 10–1500 ng mL−1 for propofol and 1-QG, 20–3000 ng mL−1 for PG and 25–3750 ng mL−1 for 4-QG. The regression curves were linear for all compounds. The method is accurate and precise with intra-assay and inter-assay precision <8% and bias ≤6% for all compounds. This assay has allowed the successful measurement of propofol and its main glucuroconjugate metabolites in human plasma from 24 patients undergoing anaesthesia for elective partial hepatectomy surgery.