title: Optimisation of an extraction method for the determination of prostaglandin E2 in plasma using experimental design and liquid chromatography tandem mass spectrometry.
abstract: A new extraction method has been developed for the extraction of prostaglandin E(2) (PGE(2)) from human plasma of patients suffering chronic inflammatory disorders. The extraction solvents were optimised systematically and simultaneously by using a central composite design. The optimised method involves precipitation of the protein fraction, centrifugation, evaporation and dissolution of the supernatant in the mobile phase, screening to confirm the presence of the analyte, and quantification of the positive samples by liquid chromatography tandem ion-trap mass spectrometry. Tandem mass spectrometry in negative mode was performed by isolating and fragmenting the ion [PGE(2)-H](-) signal m/z 351. Identification and quantification was carried out by extracting the ion fragment chromatograms at 333, 315 and 271 m/z. The quantitative determination was linear for the low nanogram (1-50 ng/ml) and upper picogram (400-1000 pg/ml) range studied, using 15 and 0.5 ng/ml of internal standard, respectively. The lower limit of detection was 2.5 pg for an injection volume of 25 microl. The optimised extraction method showed high reproducibility (coefficients of variation<4%) and recovery values, estimated from standard addition experiments, ranging from 96 to 98%.
authors.affiliation: National Institute of Nutrition and Seafood Research (NIFES), P.O. Box 2029 Nordnes, N-5817 Bergen, Norway. pedro.araujo@nifes.no
authors.forename: Pedro
authors.initials: P
authors.lastname: Araujo
authors.forename: Livar
authors.initials: L
authors.lastname: Frøyland
mesh_terms: D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods*; D002908:Chronic Disease; D015232:Dinoprostone / Q000097:blood* / Q000302:isolation & purification*; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage / Q000627:therapeutic use; D043371:Fatty Acids, Omega-6 / Q000008:administration & dosage / Q000627:therapeutic use; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000188:drug therapy; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D015232:Dinoprostone