Amperometric determination of hydralazine hydrochloride in a flowing stream at the glassy carbon electrode.

A flow-injection method for the determination of hydralazine hydrochloride based on electrochemical oxidation at the glassy carbon electrode is presented. The amperometric method is highly specific and may be used to determine hydralazine hydrochloride in the presence of other drugs commonly found in its pharmaceutical dosage forms or administered concurrently in therapeutic situations. By using an electrode potential of +650 mV versus an Ag/AgCl reference electrode, a calibration curve was found to be linear in the 1-50-micrograms/mL concentration range, with minimum detectability at 10 ng (signal-to-noise ratio, 2). When the method was applied to the analysis of hydralazine hydrochloride in selected pharmaceutical dosage forms, it showed good accuracy and precision. Although automation was not used in this study, the method could readily be incorporated in automated systems because it employs the technique of continuous analysis in a flowing stream.