Determination of 8‐epi PGF 2 α concentrations as a biomarker of oxidative stress using triple‐stage liquid chromatography/tandem mass spectrometry

F2‐isoprostanes are a family of prostaglandin F2‐like compounds that are formed by free‐radical‐catalyzed peroxidation of arachidonic acid. Several F2‐isoprostanes, but in particular 8‐epi PGF 2 α , are widely used as oxidative stress biomarkers. An analytical method based on liquid chromatography with negative electrospray ionization (ESI) coupled to tandem mass spectrometric detection (LC/MS/MS) was developed for the determination of 8‐epi PGF 2 α concentrations in human plasma, whole blood, erythrocytes and urine. 8‐epi PGF 2 α ‐d4, a stable isotope derivative of 8‐epi PGF 2 α , was used as an internal standard (IS). A 50 µL sample was focused on‐column and separated on two 3 µm particle size SUPELCOSIL™ ABZ+Plus HPLC columns (15 cm × 4.6 mm and 7.5 cm × 4.6 mm) connected in series. An Applied Biosystems 4000 Q TRAP LC/MS/MS system with ESI was operated in multiple reaction monitoring (MRM) mode with the precursor‐to‐product ion transitions m / z 353.4 → 193.1 (8‐epi PGF 2 α ), 357.4 → 197.1 (8‐epi PGF 2α ‐d4), used for quantification. The assay was fully validated and found to have adequate accuracy, precision, linearity, sensitivity and selectivity. The mass limit of detection (mLOD) was 1 pg of analyte eluting from the column. The assay has been successfully applied to the analysis of human plasma, whole blood, erythrocytes and urine samples. Copyright © 2009 John Wiley & Sons, Ltd.