Screen-Printed Carbon Electrode Modified with Poly-L-histidine Applied to Gold(III) Determination

A sensitive voltammetric method for trace measurements of gold(III) ions using a screen-printed carbon electrode modified with poly-L-histidine is described. The new procedure is based on the accumulation of the tetrachloroaurates complex at the electrode surface under an open circuit potential condition, followed by a cathodic stripping scan of potential. Parameters such as film preparation, pH, accumulation potential and deposition time have been optimized to obtain the best voltammetric response. Using optimal experimental conditions, analytical curves for gold ions were obtained using a linear sweep (LSV), differential pulse (DPV), and square wave voltammetry (SWV). Limits of detection of 6.0 x 10(-6) mol L-1, 1.7 x 10(-6) mol L-1 and 4.0 x 10(-6) mol L-1 were estimated for the LSV, DPV and SWV, respectively. The method was successfully applied to the determination of gold ions in human urine samples.