Voltammetric determination of D-penicillamine based on its homogeneous electrocatalytic oxidation with potassium iodide at the surface of glassy carbon electrode

The electrooxidation of D -penicillamine ( D -PA) has been studied in the presence of potassium iodide in various buffered aqueous solutions (4.00 ≤ pH ≤ 9.00) at the surface of glassy carbon electrode using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. It has been found that under optimum pH (pH 5.00) in cyclic voltammetry, the electrooxidation of D -PA in the presence of potassium iodide as a homogeneous mediator occurred at a potential about 220 mV less positive than that in absence of potassium iodide at the surface of glassy carbon electrode. The homogeneous electrocatalytic oxidation current wave of D -penicillamine was linearly dependent on the D -PA concentration and a linear calibration curve was obtained in the ranges 3.0 × 10 −5 −1.5 × 10 −3 M and 9.0 × 10 −6 −1.2 × 10 −4 M of D -PA with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods, respectively. The detection limits (2σ) were determined as 3.0 × 10 −5 and 3.5 × 10 −6 M with CV and DPV, respectively. This method was also used for voltammetric determination of D -PA in pharmaceutical preparation by standard addition method.