CAPILLARY GAS-CHROMATOGRAPHIC DETERMINATION WITH NITROGEN-PHOSPHORUS DETECTION OF THE CALCIUM-ANTAGONIST NICARDIPINE AND ITS PYRIDINE METABOLITE M-5 IN PLASMA

A capillary gas chromatographic method with nitrogen-phosphorus detect ion for the simultaneous determination of nicardipine and its pyridine metabolite M-5 was developed. The method involves extraction of the p lasma with hexane-methylene chloride (1:1, v/v), followed by evaporati on of the organic phase. The extract is injected into a fused-silica c apillary column coated with cross-linked 5% phenyl-methylsilicone. A t emperature gradient (85-285 degrees C) is applied and the two products and the internal standard can be separated within 22 min. The limit o f detection is 0.5 ng/ml for both products. The method is suitable for pharmacokinetic studies in humans.