Anion-exchange method for speciation of arsenic and its application to some environmental analyses

Abstract

A relatively straightforward two-stage anion exchange method has been developed for the speciation of inorganic arsenic(V) and arsenic(III), monomethylarsonic acid and dimethylarsinic acid. Arsenic(III) and dimethylarsinic acid are eluted in succession with a carbon dioxide - hydrogen carbonate buffer at pH 5.5. Separation of monomethylarsonic acid and inorganic arsenic(V) is then obtained by elution with carbon dioxide - sodium chloride solution at pH 4.0–4.2. The method has been applied to the analysis of sediment interstitial waters, and three species of aquatic plants.