Gas-chromatographic determination of disopyramide and its mono-N-dealkylated metabolite in serum with use of a nitrogen-selective detector.

I describe a rapid, simple routine gas-liquid chromatographic method for simultaneous isothermal quantitation of disopyramide and its mono-N-dealkylated metabolite. The method involves one extraction step with dichloromethane, derivatization of the metabolite, and gas chromatography with an OV-17 liquid phase. Standard curves were linear over the concentration range tested (0.1-25 mg/L) and the maximum coefficient of variation was 9.2%. Quantitation of both disopyramide and its mono-N-dealkylated metabolite with the present method is less time-consuming than are gas-chromatographic methods previously described.