Speciation of Arsenic(III) and Arsenic(V) in Sediment Extracts by High-Performance Liquid Chromatography−Hydride Generation Atomic Absorption Spectrophotometry

Determining the redox states of arsenic (As) in environmental samples is important due to the pronounced differences in toxicity and mobility of the various forms. We have combined the separation capabilities of high-performance liquid chromatography (HPLC) with the sensitivity and element specificity of hydride generation atomic absorption spectrometry (HGAAS) to determine arsenite [As(III)] and arsenate [As(V)], which have been shown to be the most toxic and prevalent forms of As in soil and water. The HPLC−HGAAS technique gave retention times of 2.2 and 4.2 min for As(III) and As(V), respectively. Detection limits of 200 pg of As (0.8 μg L - 1 As in solution) were obtained for both As(III) and As(V). The technique was used to determine As(III) and As(V) in deionized water and 1 mM PO 4 sequential extracts of estuarine sediment, coal fly ash, and saline evaporation pond sediment. Coal fly ash contained no detectable deionized water-extractable As(III) or As(V), but contained appreciable PO 4 -extractable As(V). The As(III) species was detected in all extracts of estuarine sediment, though 1 mM PO 4 released primarily As(V). Evaporation pond sediment also contained primarily PO 4 -extractable As(V).