Simultaneous quantification of F2-isoprostanes and prostaglandins in human urine by liquid chromatography tandem-mass spectrometry

A specific and sensitive LC–MS/MS method for analysis of F2-isoprostanes (F2-IsoPs) and prostaglandins (PGs) in urine was developed and validated to examine the levels of F2-IsoPs and prostaglandin F2α (PGF2α), in human urine in patients undergoing cardiac surgery. The rapid extraction for F2-IsoPs and PGs from urine was achieved using a polymeric weak anion solid phase extraction cartridge. The base-line separation of 8-iso-PGF2α, 8-iso-15(R)-PGF2α, PGF2α, and 15(R)-PGF2α was carried out on a Hydro-RP column (250 mm × 2.0 mm i.d., Phenomenex, CA) using a linear gradient of methanol:acetonitrile (1:1, v/v) in 0.1% formic acid at a flow rate of 0.2 mL/min. The method was proved to be accurate and precise for simultaneous quantification of each analyte over a linear dynamic range of 0.05–50 ng/mL with correlation coefficients greater than 0.99. The intra-day and inter-day assay precision at the lowest quality control (0.07 ng/mL) level were less than 17%. The mean extraction recoveries of F2-IsoPs and PGs were in a range of 79–100%. In applications of this method to patients undergoing cardiac surgery, post-surgery urinary concentrations of 8-iso-PGF2α increased significantly in patients (n = 14) who did not develop acute kidney (AKI) (pre-surgery 0.344 ± 0.039 vs. post-surgery 0.682 ± 0.094 ng/mg creatinine, p < 0.01), whereas there was no significant change in this isoprostane in the patients (n = 4) who developed AKI (pre-surgery 0.298 ± 0.062 vs. post-surgery 0.383 ± 0.117 ng/mg creatinine, NS). Therefore, the method is suitable for the analysis of individual F2-IsoPs and PGF2α’s in both clinical and research studies.