MINIMIZATION OF PLASMA INTERFERENCES BY LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION AFTER ULTRAVIOLET-IRRADIATION USING CHLORDIAZEPOXIDE AS A MODEL SUBSTANCE

Chlordiazepoxide was detected as a model substance in plasma by electr ochemistry after separation by reversed-phase liquid chromatography. T he method, which incorporates post-column, on-line UV irradiation, exp loits the transformation of the molecule both into a phenolic hydroxyl and an oxaziridine by photolysis. For the determination in biological material, the optimization with respect to pH and working potential i n combination with solid-phase extraction results in a decrease of pla sma interferences. Selectivity and sensitivity can so be significantly improved. The detection limit was 3 ng/ml.