title: Determination of carprofen in blood by gas chromatography chemical ionization mass spectrometry.
abstract: A gas chromatographic chemical ionization mass spectrometric assay has been developed to measure carprofen in blood. The method features the addition of either a structural or stable isotope analog internal standard to plasma prior to a simple benzene extraction at pH 4.5. The residue, after removal of the benzene, is methylated with ethereal diazomethane. Following evaporation of the methylating solvents, a portion of the reconstituted residue is analyzed by gas chromatography mass spectrometry. The mass spectrometer is set to monitor in the gas chromatographic effluent the [MH]+ ions of carprofen methyl ester and the methyl ester of the internal standard generated by isobutane chemical ionization. Assay sensitivity is 5 pmol ml-1. When 200 pmol ml-1 samples are analyzed using a stable isotope analog as the internal standard, the precision and accuracy are both 4%. Using a structural analog as the internal standard, the assay was neither as precise nor as accurate.
mesh_terms: D002227:Carbazoles / Q000097:blood*; D002849:Chromatography, Gas; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D011422:Propionates / Q000097:blood*
chemical_list: D002227:Carbazoles; D011422:Propionates