A differential pulse voltammetric determination of nisoldipine using glassy carbon electrode in pharmaceutical preparations

A differential pulse voltammetric method is described for the determination of nisoldipine based on the oxidation of the dihydropyridine group on the surface of a rotating glassy carbon disk electrode. The voltammetric behavior of this compound was investigated in the supporting electrolyte consisting of 0.2 M KCl, 0.1 M phosphate buffer and 30 percent ethanol during the investigation of the pH effect. The maximum signal to noise ratio and the most symmetrical peaks were obtained in the use of the supporting electrolyte solution containing 0.1 M H2SO4 in 30 percent ethanol and initial potential of +300 mV. The factor affecting the voltammetric current was diffusional in the range of 200-2000 rpm and up to 1x10(-4) M nisoldipine concentration. The detection limit and reproducibility were calculated to be 8x10(-6) M for the concentration of 7.8x10(-5) M NSD, accepting the ratio of signal-to-noise (S/N) equal to 3 and 0.9 % for 5 successive experiments, respectively. The DP voltammetric determination of nisoldipine in film coated tablets was conducted using optimum rotating conditions. According to the statistical evaluations acceptable results were obtained. Therefore, the method proposed in this study is practical, sensitive and accurate for the analysis of nisoldipine preparations in the quality control laboratories.