Rapid and sensitive quantification of 8-isoprostaglandin F2α in human plasma and urine by liquid chromatography–electrospray ionization mass spectrometry

The isoprostane, 8-isoprostaglandin F2α (8-iso-PGF2α), is produced non-enzymatically by direct oxidation of arachidonic acid on the cell surface by oxygen radicals. We developed a new assay method for 8-iso-PGF2α using 2H4-8-iso-PGF2α as the internal standard (I.S.) by high-performance liquid chromatography–electrospray ionization-mass spectrometry (LC–ESI-MS). For this assay, we established a very simple and rapid pretreatment method using a membrane filter-type solid-phase extraction column (Empore™ disk cartridge) for human urine extracts or intact plasma. LC–ESI-MS was performed in the selected ion monitoring (SIM) mode using target ions at m/z 353.24 (8-iso-PGF2α) and m/z 357.26 (I.S.) with a resolution of 1500. The imprecision for this method was below 13.7%. Mean inaccuracy was 8.7% for added levels of 8-iso-PGF2α up to 5000 pg/ml of urine and 500 pg/ml of plasma. Determination of plasma and urinary 8-iso-PGF2α concentrations in healthy subjects by the present method revealed that its urinary concentration in smokers tends to be higher than that in nonsmokers.