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Application of Capillary Electrophoresis to Anion Speciation in Soil Water Extracts II. Arsenic
Author(s) -
Naidu R.,
Smith J.,
McLaren R. G.,
Stevens D. P.,
Sumner M. E.,
Jackson P. E.
Publication year - 2000
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2000.641122x
Subject(s) - capillary electrophoresis , chromate conversion coating , chemistry , arsenic , capillary action , electrolyte , genetic algorithm , analytical chemistry (journal) , chromatography , electrophoresis , detection limit , chromium , materials science , electrode , evolutionary biology , composite material , organic chemistry , biology
A method has been developed for the speciation of arsenic (AsO − 2 , AsO 3− 4 , and dimethylarsinic [DMA]) in natural soil solutions from contaminated sites in Australia. The separation of these anions was achieved by capillary zone electrophoresis (CZE) using a fused silica capillary (72‐cm by 50‐μm i.d.) with a basic chromate buffer and on‐column indirect UV detection at 254 nm. Method parameters, such as electrolyte pH, run voltage, and capillary temperature were studied in order to establish suitable analytical conditions. The ideal separation for As(III) and DMA was achieved with a buffer pH of 8.0, a run voltage of 25 kV, and a capillary temperature of 30°C. Under these conditions, As(V) and orthophosphate ions comigrated. However, the use of a chromate buffer at pH 10, a run voltage of 20 kV, and capillary temperature of 20°C led to complete separation of As(V) and phosphate peaks. Results of these investigations together with recovery test data suggest that separation of the As species from soil solutions can be achieved in less than 5 min with detection limits of 0.50, 0.10, and 0.10 mg L −1 for As(III), As(V), and DMA, respectively.