Speciation of Arsenic(V) and Arsenic(III) in Soil Extracts by Cathodic Stripping Voltammetry

Cathodic stripping voltammetry with a hanging mercury drop electrode was applied for the determination of As(III) and As(V) in soil extracts. The content of inorganic arsenic(III) and arsenic(V) compounds was determined after chemical reduction of arsenic(V) by KI and ascorbic acid solution, while arsenic(III) was determined in the solution without the reduction. Organic compounds were determined after UV irradiation of the samples. For arsenic compounds extraction three different extractants were tested: water/methanol, ortophosphoric acid and mixture of HCl/HNO3. As different arsenic forms have different toxicity, the ability to discriminate between them is a distinct advantage of the proposed method.