Polarographic determination of chlorhexidine in pharmaceutical preparations

The electroreduction of chlorhexidine has been studied by d.c, a.c. and pulse polarography. Polarograms of the drug recorded from ammonium acetate buffers exhibit a single well-defined wave. The current is diffusion-controlled and proportional to the concentration. The reduction wave is due to an irreversible 8-electron reduction of the four > C=NH groups in the molecule to amino groups. The drug is strongly adsorbed on the electrode surface over a considerable potential range. Hence, the drug can be determined by polarography in the presence of other weaker surfactants often present in pharmaceutical formulations. Procedures have been proposed for pulse-polarographic determination of the drug in antiseptic cream and liquids. The proposed method is simple and accurate and does not involve time-consuming separation of the drug from insoluble constituents present in the sample.