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 a parts per thousand currency sign pH a parts per thousand currency sign 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 x 10(-5)-1.5 x 10(-3) M and 9.0 x 10(-6)-1.2 x 10(-4) M of D-PA with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods, respectively. The detection limits (2 sigma) were determined as 3.0 x 10(-5) and 3.5 x 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.