Hydride generation atomic fluorescence spectrometry (HG-AFS) as a sensitive detector for Sb(III) and Sb(V) speciation in water

Abstract

A procedure for the separation and determination of inorganic species of antimony based on the use of coupled high-performance liquid chromatography (HPLC) hydride generation (HG) atomic fluorescence spectrometry (AFS) is described. Sb(III) and Sb(V) were separated on a miniaturized anion-exchange column (Supelcosil LC-SAX 1, 2 cm × 4.6 mm id) using a 0.06 mol l⁻¹ ammonium tartrate aqueous solution at pH 6.9 as eluent. The retention times were 0.45 and 3.5 min for Sb(V) and Sb(III), respectively. The hydrides were generated on-line with 3% m/v NaBH₄ and 2 mol l⁻¹ HNO₃ aqueous solutions. The intensity of emission was linearly related to the concentration of the Sb(V) species in the range 1.0–50.0 µg l⁻¹ (r² = 0.9976) and of Sb(III) in the range 3.0–200 µg l⁻¹, with detection limits of 0.8 and 1.9 µg l⁻¹, for Sb(V) and Sb(III), respectively. The precision evaluated using the relative standard deviation (RSD) was 4.4 and 2.5% (n = 10) for Sb(V) and Sb(III) at concentrations of 10 µg l⁻¹, respectively. The method has a sensitivity suitable for monitoring drinking and surface water according to the regulations established by the EU directives for antimony (10 µg l⁻¹) and has been applied to the speciation of inorganic antimony in several spiked water samples.