GLC determination of procainamide in biological fluids

A GLC method for the determination of procainamide in biological fluids is presented. By using a dipropyl analog of procainamide as an internal standard, both compounds can be chromatographed directly, yielding linear calibration curves and a sensitivity that allows quantitative determination of concentrations as low as 0.1 mug/ml. The extraction procedure was carefully modified to avoid hydrolysis of N-acetylprocainamide, a major metabolite of procainamide. The usefulness of the procedure is demonstrated by following the disappearance of procainamide from the plasma and urine of human subjects treated with the drug.