Potential of high performance liquid chromatography coupled to flow injection hydride generation atomic absorption spectrometry for the speciation of inorganic and organic antimony compounds

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 mu g l(-1). Detection limits of 0.4, 0.7, and 1.0 mu g l(-1) for TMSbCl2, Sb(III), and Sb(V) were obtained.