Determination of vinca alkaloids in plasma and urine using ion-exchange chromatography on silica gel and fluorescence detection.

The development of a method for the determination of the antineoplastic vinca alkaloids vinblastine and vindesine in biological samples is described. The selectivity of the assay is high owing to the use of solid-phase extraction on a cyanopropyl extraction column prior to isocratic chromatography on unmodified silica gel with fluorescence detection. The influence of acetonitrile concentration and mobile phase pH on the capacity factors of the drugs was studied in order to optimize the separation between the drugs and endogenous components. The effect of varying the type and concentration of competing cations in the mobile phase was also examined. The limit of determination (signal-to-noise ratio = 3) for vinblastine is 0.5 ng/ml in plasma and urine and for vindesine 2.5 ng/ml. The assay is suitable for determining the concentrations of both compounds in plasma and urine samples from patients.