Determination of As(III) by anodic stripping pulse voltammetry using gold and glassy carbon electrodes

Abstract

Determination of As(III) by anodic stripping pulse voltammetry (ASPV) in acetonitrile (0.1 <em>M </em>Li ClO₄) using gold electrode has been studied. A number of supporting types of pulses have been examined, and the pulses of linearly increasing amplitude found to give the greatest sensitivity. The relative standard deviation is 3.5% at very low concentration of 0.3 ng/L (4 x 10^-12<em>M</em>). The simultaneous discharge-ionization of arsenic with mercury and copper has also been studied by ASPV on a glassy carbon electrode in acetonitrile (0.1 <em>M </em>LiClO₄). It is shown that co-deposition leads to the formation of Hg₃As₂ and Cu₃As. As(III) can be determined with increase in sensitivity from 5 x 10^-5 <em>M </em>to 5 x 10^-8 <em>M </em>and 1 x 10^-7 <em>M </em>of As(III) by adding Cu(II) and Hg(II) to the solution, respectively. The relative standard deviation is 2.1% to 7.4%.