SENSITIVE AND SPECIFIC LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY METHOD FOR ASSAY OF FLUOXETINE AND ITS METABOLITE NORFLUOXETINE IN HUMAN PLASMA AND APPLICATION OF METHOD TO PHARMACOKINETIC ANALYSIS

摘要

A simple, specific and sensitive high-performance liquid chromatography - electrospray tandem mass spectrometry method is developed for the simultaneous determination of fluoxetine and its metabolite norfluoxetine in human plasma. Plasma samples weresimply treated with acetonitrile to precipitate and remove proteins and the isolated super- . natants were directly injected into the high-performance liquid chromatography - electrospray tandem mass spectrometry system. Chromatographic separation of theanalytes was achieved on a Discovery C_(18) (100 x 2.1 mm ID., particle size 3.0 mu m) column using 0.1% formic acid in water—acetonitrile (40:60) as mobile phase with a flow rate of 0.2 mL/min. Diazepam was used as the internal standard. The compoundswere ionized in the electrospray ionization source of the mass spectrometer and were detected by selected reaction ion monitoring of the transitions of m/z 310 —> mlz 44.3 for fluoxetine, m/z 296 —> m/z 134 for norfluoxetine and m/z 285 —> m/z 193 for the internal standard. The method has low limit of detection (LOD) of 0.02 ng/mL and 0.03 ng/mL for fluoxetine and norfluoxetine, respectively. The inter- and intra-run precision was measured to be below 5.3% (relative standard deviation) for both fluoxetine and norfluoxetine. The developed method was successfully used to investigate plasma concentrations of fluoxetine and norfluoxetine in the pharmacokinetic study of Chinese volunteers who received fluoxetine orally.