Speciation of antimony(III) and antimony(V) species by using high-performance liquid chromatography coupled to hydride generation atomic absorption spectrometry

Abstract

A miniaturized HPLC column (Supelcosil LC-SAX 1, 2 cm×4.6 mm id) was coupled to HGAAS for the speciation of inorganic Sb^III and Sb^V species in spiked water samples. The baseline separation of these two Sb species was achieved by using aqueous 50 mmol l^–1 tartrate solution at pH 5.5 as eluent. The retention times were 0.5 and 2.8 min for Sb^V and Sb^III, respectively. The hydrides were generated with 3% NaBH₄ and 1.8 mol l^–1 HCl solutions. The absorbance was linearly related to the concentration of Sb^V species in the range 2.5–100 µg l^–1 (r=0.9996) and of Sb^III species in the range 5.0–100 µg l^–1 (r=0.9990) with detection limits of 1.0 and 2.0 µg l^–1, for Sb^V and Sb^III, respectively. The precision, evaluated by using the relative standard deviation (RSD), was 3.3% and 1.5% (n=10) for Sb^V and Sb^III at concentrations of 50 µg l^–1, and 4.1% and 3.9% (n=10) at concentrations of 10 µg l^–1, respectively. The detection limits achieved in the present work are acceptable for screening samples with respect to the EU drinking and surface water limits (10 µg l^–1), but are not sufficiently sensitive to measure real levels in natural waters. The accuracy of the method was evaluated by the analysis of Sb species in several spiked water samples, as there is yet no certified reference material available.