Improved semi-automated analysis of procainamide and N-acetyl procainamide utilizing a totally volatile mobile phase

A semi-automated technique has been devised for the analysis of the antirhythmic drugs, procainamide (PA) and N-acetyl procainamide (NAPA) from human serum. Reverse-phase high-performance liquid chromatographic (HPLC) separations were performed by means of an autoinjector system in combination with microBondapak C18 column. A mobile phase containing only volatile buffers (e.g., triethylamine-acetic acid or N-ethyl morpholine-acetic acid) at apparent pH 5.3 was necessitated to prevent the buildup of salt residues on the valves and fittings within the autoinjector and high pressure pump. For HPLC analysis of these drugs, the within-run precision, as estimated by coefficient of variation analysis, was less than 9%. Comparable precision was shown for day-to-day variation in analysis. No interference was noted from 20 other substances, metabolites or drugs that might be present in the sera extracts. This semi automated procedure has been utilized successfully to quantitate over 200 patient sera on a bach or emergency basis.