The use of a pre-column for the direct high-performance liquid chromatographic determination of the anti-depressants clovoxamine and fluvoxamine in plasma

A high-performance liquid chromatographic system for the direct determination of the antidepressants clovoxamine and fluvoxamine in plasma is described. The primary amines are derivatized with the fluorogenic reagent fluorescamine in order to increase the sensitivity and selectivity, but also to decrease the polarity of the amines. The band broadening of some combinations of pre-column and analytical column is compared for the fluorescamine derivative of fluvoxamine. The combination of a pre-column containing RP-2 and an analytical column containing RP-8 has been successfully used for the determination of the two antidepressants in plasma. At relatively low concentrations of the drugs, a simple step-gradient elution is required for the removal of a large proportion of the more polar components of the samples. Concentrations in the range of 10-1000 ng clovoxamine per ml plasma were determined by means of external standardization and show a good correlation with the data of a more laborious gas chromatographic method. The detection limits for clovoxamine and fluvoxamine are approximately 3 ng/ml in plasma.