Simple gas-liquid chromatographic method for the measurement of disopyramide in blood-plasma or serum and in urine.

A simple method has been developed for the measurement of disopyramide in blood-plasma or serum at the concentrations attained during therapy. A relatively small (200 microliter) sample volume is made basic and extracted with 50 microliter of chloroform containing an internal standard, and the extract is analysed directly by gas-liquid chromatography with flame-ionization detection. The instrument calibration is linear and passes through the origin of the graph. Neither solvent transfer nor evaporation steps are used in the extraction procedure, which takes less than 3 min to complete, and urine specimens may be analysed by an analogous technique. No interference from either endogenous sample constituents or other drugs has been observed, although a simple back-extraction procedure is described which eliminates potential interference from a small number of basic and neutral drugs.