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.