Electrochemical and analytical performance of boron-doped diamond electrode for determination of ascorbic acid

The electrochemical behavior and determination of ascorbic acid (AA) was investigated at a bare boron-doped diamond (BDD) electrode using cyclic and differential pulse voltammetry. The influence of pH of supporting electrolyte and scan rate on the current response of analyte was examined to select the suitable experimental conditions. It was found that AA provided one well-shaped irreversible and diffusioncontrolled oxidation peak at +0.87 V vs. Ag/AgCl in Britton-Robinson buffer pH 4.0. Applying differential pulse voltammetry, the peak current of AA was linearly proportional to its concentration from 5 × 10^-6 to 2 × 10^-4 mol L^-1 (R² = 0.999), with the limit of detection of 1.1 × 10^-6 mol L^-1 and the good repeatability (relative standard deviation of 2.3 %). The developed electroanalytical protocol was successfully applied to determine the content of AA in commercial pharmaceutical preparations, based on the standard additions method, with the obtained recovery of 122 %. The accomplished analytical performance indicates that BDD electrodes are promising electrochemical sensors for pharmaceutical analysis.