Polarographic and voltammetric determination of chlorhexidine in pharmaceutical preparations

Direct-current polarography (DCP) involving sampled current measurement, di fferential pulse polarography (DPP), square-wave voltammetry (SWV) and cycl ic voltammetry (CV) with a controlled-growth mercury drop electrode (CGMDE) were used to determine chlorhexidine (ChH). The DCP method was used to stu dy wave height and wave potential in relation to pH of the solution over a range 1-11. Optimum measurement parameters and supporting electrolyte compo sitions were established. The currents observed with the mercury electrodes were found to be diffusion and irreversible. By using the adsorptive SWV, SWV and DPP methods, current intensity was found to vary linearly with ChH concentration over the ranges 40-100 ng ml(-1), 0.25-20 mu g ml(-1), and 25 -100 mu g ml(-1), respectively. The DPP and SWV methods were adapted for th e determination of chlorhexidine in the solid substance, in eye drops and i n contact-lens preservation solutions (by the standard-addition technique). A statistical analysis of the analytical results showed both methods to be characterized by satisfactory accuracy and precision (RSD 0.87% and 1.19%, respectively).