Preconcentration of inorganic species of antimony by sorption on Polyorgs 31 followed by atomic absorption spectrometry detection

A method of speciation determination of inorganic antimony, based on selective sorption of Sb(III) and Sb(V) on Polyorgs 31 complexing sorbent under pH-controlled conditions, is described. The determination of inorganic forms of antimony at ng 1(-1) level was possible due to the quantitative sorption of total inorganic antimony (Sb(III)+Sb(V)) at pH 2 and Sb(III) only at pH 10, on Polyorgs 31 containing mainly amidoxime and amine functional groups. After the concentration step, the sorbent was injected into a graphite furnace in the form of a suspension and the atomic absorption signal of Sb was measured. Conditions for the sorptive preconcentration process as well as the electrothermal atomization of Sb sorbed on Polyorgs 31 were optimized. The preconcentration factor was about 50 (200 ml sample volume), and under the optimized conditions the concentration detection limits of 30 and 34 ng 1(-1) were obtained for Sb(III) determined at pH 2 and pH 10, respectively, and 31 ng 1(-1) for Sb(V) at pH 2. The precision of determination (RSD) of Sb at the concentration level of 0.2 mu g 1(-1) was below 5% (n=4) at both pH 2 and pH 10. The method has been applied to the speciation of inorganic antimony in tap water and snow samples.