Preconcentration and separation of inorganic selenium species on activated alumina

A simple and convenient method has been developed for the speciation of inorganic selenium in aqueous solutions using alumina microcolumn. Both Se(IV) and Se(VI) are retained on the microcolumn in a widely pH range of solution. The successive gradient elution of preconcentrated species with ammonia solution allows to differentiate between them. Se(VI) and Se(IV) were eluted with 1 ml of 1 mol l(-1) NH3 and 6 ml of 4 mol l(-1) NH3, respectively, and determined by graphite furnace atomic absorption spectrometry. The detection limit for Se(VI) is 0.80 mu g ml(-1) and for Se(TV) 49 ng l(-1). The method has been applied to the speciation of inorganic selenium in natural water samples. (C) 1998 Elsevier Science B.V.