Abstract

This investigation was undertaken to elucidate the potential of high-performance liquid chromatography coupled to a hydride generation system connected to an atomic absorption spectrometer (HPLC-HG-AAS) as an element specific detector for the speciation of Sb(III), Sb(V) and trimethylantimony dichloride (TMSbCl₂). HG parameters were optimised specifically with regard to the Sb-species and yielded distinctly different optima for Sb(III) and Sb(V) as regards concentrations of NaBH₄ and HCl. HCl (0.5% w/v) and of NaBH₄ (0.6% w/v) proved to be a good compromise for optimum sensitivity for all Sb species. After optimisation, signals for Sb(V) were still two times lower than for Sb(III) and TMSbCl₂. Among the five anion exchange columns tested, the Dionex AS14 provided best results for the separation of Sb(V) and Sb(III) with 1.25 mM EDTA at pH 4.7. The ION-120 column was used to separate TMSbCl₂ and Sb(V) with 2 mM NH₄HCO₃ and 1 mM tartaric acid at pH 8.5. When separating the three Sb-species in a single chromatographic run, sharp peaks for Sb(V) and Sb(III), but a very broad peak for TMSbCl₂, were obtained. In all chromatographic separations the peaks could be baseline separated. Calibration curves were linear between 2 and at least 100 µg l⁻¹. Detection limits of 0.4, 0.7, and 1.0 µg l⁻¹ for TMSbCl₂, Sb(III), and Sb(V) were obtained.