SPECIATION AND PRECONCENTRATION OF SB(III) AND SB(V) ON ALUMINA USING PHOSPHORIC-ACID UNDER PH-CONTROLLED CONDITIONS

A method of speciation of inorganic antimony, based on the selective retention of Sb(III) and Sb(V) on alumina using a complexing agent under pH-controlled conditions, is described. The effect of pH on the retention of both species was studied in five media: water, citric acid, tartaric acid, phosphoric acid and hydrochloric acid. The analytical results demonstrated that Sb(III) and Sb(V) can be quantitatively separated in phosphoric acid, since at pH 9.5 the retention of Sb(V) is negligible (less than 1%) on the column while Sb(III) is selectively eluted. At pH 7.5 both species are retained. Retention and preconcentration do not depend on the basicity or acidity of the alumina, which suggests that adsorption-desorption is the prevailing mechanism on the alumina microcolumn. The method has been successfully applied to the speciation of Sb in spiked sea-water samples.