ELECTROANALYTICAL CHEMISTRY STUDY OF PILOCARPINE

The electrochemical behaviour of pilocarpine was investigated by differential pulse polarography and cyclic voltammetry. The optimum conditions for the determination of pilocarpine were as follows: The electrolyte was 0.4 mol/L HAc-NaAc(pH 4.0) buffer solution, Zn (Ⅱ) 1.0×10^-3 mol/L; initial potential -0.80 V(vs Ag-AgCl), final potential-1.30 V(vs Ag-AgCl), and voltage sweep rate 5 mV/s. A fair reproducibility in the above procedure and a good relationship between peak current and pilocarpine concentration (4.0×10^-6～4.0×10^-5 mol/L) were achieved. The detection limit was 8.0×10^-7 mol/L. This paper also reports that the application of cyclic voltammetry to study electrode process behavior has been established. The PVC membrane ion-selective electrode for pilocarpine also was studied. It is based on the use of tetraphenylborate pilocarpine ion pair complex as the active material. The PVC membrane electrode showed Nernstian response over the pilocarpine concentration range from 1.0×10^-2to 3.0×10^-5mol/L, with a slope of 36 mV/decade, the detection limit being 3.0×10^-6 mol/L. The electrode gave fast response and good reproducibility. This method provides a rapid and simple way to the determination of pilocarpine in pharmaceutical preparations.