Homogeneous electrocatalytic oxidation of d-penicillamine with ferrocyanide at a carbon paste electrode: application to voltammetric determination

The electrooxidation of d-penicillamine (d-PA) was studied in the presence of ferrocyanide as a homogeneous mediator at the surface of a carbon paste electrode in aqueous media using cyclic voltammetry (CV) and chronoamperometry. Under optimum pH in CV the oxidation of d-PA occurs at a potential about 380 mV less positive than that in the absence of ferrocyanide. The catalytic oxidation peak current was dependent on the d-PA concentration and a linear calibration curve was obtained in the ranges 4.0 × 10−5–2.0 × 10−3 M and 8.0 × 10−6–1.8 × 10−4 M of d-PA with CV and differential pulse voltammetry (DPV) methods, respectively. The detection limits (3σ) were determined as 1.9 × 10−5 and 3.2 × 10−6 M by CV and DPV methods. This method was also used for the determination of d-PA in pharmaceutical preparations by the standard addition method.