In Search of a Speciation Method for Arsenic in Mine-Influenced Waters: Is Differential Pulse Anodic Stripping Voltammetry the Answer?

This study investigated whether differential pulse anodic stripping voltammetry (DPASV) with a solid gold electrode could be used for arsenic speciation of mine-influenced water. The DPASV parameters were optimized using a 100-mu g L-1 As(III) standard solution. The procedure for chemical reduction of As(V) to As(III) using thiosulfate prior to DPASV measurements was also optimized. Two samples of mine-influenced waters from the Witwatersrand mining area, an acid mine drainage (AMD) and a more dilute Fleurhof dam water sample, were used to assess the method viability. Interference from elements in the AMD proved insurmountable using this technique alone; the method was also unable to detect arsenic in the dam water sample. However, spiked dam water samples gave percent recoveries of 81.6% and 123% for As(III) and As(V), respectively, showing that arsenic species in mine-influenced water can be effectively determined if the method is reoptimized for lower arsenic concentrations.