Determination of copper(II) by anodic stripping voltammetry at a 2,5-dimercapto-1,3,4-thiadiazol self-assembled...

2,5-Dimercapto-1,3,4-thiadiazol (DMTD) can bind on the surface of a gold electrode through the strong gold-sulfur interaction. The fabrication and electrochemical characteristics of the DMTD self-assembled monolayer (SAM)-modified gold electrode were investigated. The DMTD SAM electrode exhibited a significantly increased sensitivity. Cu(II) was accumulated in phosphate buffer (pH 4.6) at a potential of -0.6 V (vs. Ag/AgCl) for 40 s and then determined by anodic stripping voltammetry (ASV) in copper-free phosphate buffer (pH 5.0). The effects of various parameters, such as the pH values of the preconcentration solution and measurement solution, the accumulation potential, and the accumulation time, were investigated. Under the optimum conditions, a linear calibration graph was obtained in the concentration range of 8.0 x 10(-6) to 8.0 x 10(-5) mol l(-1) with a correlation coefficient of 0.9978. The relative standard deviations for eight successive determinations were 4.3 and 2.9% for 1.0 x 10(-5) and 2.0 x 10(-5) mol l(-1) Cu(II), respectively. The detection limit (three times signal to noise) was 4.0 x 10(-7) mol l(-1). The proposed voltammetric method was utilized successfully to detect the concentration of Cu(II) ions in tap water samples.