Determination of copper in the presence of various amounts of arsenic with L-cysteine modified gold electrodes

An L-cysteine modified gold electrode for the determination of copper in the presence of various amounts of arsenic with anodic stripping voltammetry has been studied. The electrode was fabricated by immersing a gold electrode in an ethanol solution of 5mM L-cysteine for 60 min. Various parameters, such as the effect of different supporting electrolytes, the pH of the electrolyte and the deposition potential were investigated. Under optimum conditions, copper was accumulated at - 0.3 V (vs. SEC) for 60 s in 0.1 M phosphate buffer pH 5.0 in the presence of different amounts of arsenic. Essentially the same sensitivities (0.33 +/- 0.001 mu A/mu M) and limits of detection (0.13 +/- 0.002 mu M) of copper were obtained with various amount of arsenic in the range 2 mu M to 20 mu M.