title: Rapid determination of omeprazole in human plasma by protein precipitation and liquid chromatography-tandem mass spectrometry.
abstract: A rapid, sensitive and reliable method was developed to quantitate omeprazole in human plasma using liquid chromatography-tandem mass spectrometry. The assay is based on protein precipitation with acetonitrile and reversed-phase liquid chromatography performed on an octadecylsilica column (55 mm x 2mm, 3 microm particles), the mobile phase consisted of methanol-10 mM ammonium acetate (60:40, v/v). Omeprazole and flunitrazepam, the internal standard, elute at 0.80+/-0.10 min with a total run time 1.35 min. Quantification was through positive ion mode and selected reaction monitoring mode at m/z 346.1-->197.9 for omeprazole and m/z 314.0-->268.0 for flunitrazepam, respectively. The lower limit of quantitation was 1.2 ng/ml using 0.25 ml of plasma and linearity was observed from 1.2 to 1200 ng/ml. Within-day and between-day precision expressed by relative standard deviation was less than 5% and inaccuracy did not exceed 12%. The assay was applied to the analysis of samples from a pharmacokinetic study.
authors.affiliation: Pharmakl s.r.o., Seydlerova 2451, CZ-15800 Prague 13, Czech Republic. macek@pharmakl.cz
authors.forename: J
authors.initials: J
authors.lastname: Macek
authors.forename: J
authors.initials: J
authors.lastname: Klíma
authors.forename: P
authors.initials: P
authors.lastname: Ptácek
mesh_terms: D000897:Anti-Ulcer Agents / Q000097:blood* / Q000493:pharmacokinetics; D001798:Blood Proteins / Q000378:metabolism*; D011232:Chemical Precipitation; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004791:Enzyme Inhibitors / Q000097:blood* / Q000493:pharmacokinetics; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D009853:Omeprazole / Q000097:blood* / Q000493:pharmacokinetics; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000897:Anti-Ulcer Agents; D001798:Blood Proteins; D004791:Enzyme Inhibitors; D009853:Omeprazole