DETERMINATION OF FLUOXETINE AND NORFLUOXETINE IN HUMAN PLASMA BY CAPILLARY GAS-CHROMATOGRAPHY WITH ELECTRON-CAPTURE DETECTION

A capillary gas chromatographic method with Ni-63 electron-capture detection is reported for the determination of fluoxetine (Prozac) and its metabolite norfluoxetine in human plasma. A liquid-liquid extraction is used, followed by derivatization with heptafluoro-butyric anhydride to increase the sensitivity of detection. A 30 m x 0.25 mm I.D. DB-17 capillary column resolves the compounds from endogenous matrix interferences. The limit of quantitation by this method is 5 ng/ml for each compound. Stability studies show that fluoxetine and norfluoxetine are stable in human plasma for up to 96 h at room temperature and up to one year at -20-degrees-C.