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 x 10(-5)-2.0 x 10(-3) M and 8.0 x 10(-6)-1.8 x 10(-4) M of D-PA with CV and differential pulse voltammetry (DPV) methods, respectively. The detection limits (3r) were determined as 1.9 x 10(-5) and 3.2 x 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.