D. Dogrukolak et al., A DIFFERENTIAL-PULSE VOLTAMMETRIC DETERMINATION OF NISOLDIPINE USING GLASSY-CARBON ELECTRODE IN PHARMACEUTICAL PREPARATIONS, Analytical letters, 31(1), 1998, pp. 105-116
A differential pulse voltammetric method is described for the determin
ation of nisoldipine based on the oxidation of the dihydropyridine gro
up on the surface of a rotating glassy carbon disk electrode. The volt
ammetric behavior of this compound was investigated in the supporting
electrolyte consisting of 0.2 M KCl, 0.1 M phosphate buffer and 30 per
cent ethanol during the investigation of the pH effect. The maximum si
gnal to noise ratio and the most symmetrical peaks were obtained in th
e use of the supporting electrolyte solution containing 0.1 M H2SO4 in
30 percent ethanol and initial potential of +300 mV. The factor affec
ting the voltammetric current was diffusional in the range of 200-2000
rpm and up to 1x10(-4) M nisoldipine concentration. The detection lim
it and reproducibility were calculated to be 8x10(-6) M for the concen
tration 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. T
he DP voltammetric determination of nisoldipine in film coated tablets
was conducted using optimum rotating conditions. According to the sta
tistical 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 labor
atories.