Determination of antimony by atomic absorption spectrometry with flow injection hydride generation by a tetrahydroborate-form anion-exchanger

Abstract

A quartz tube atomic absorption spectrometric method for the determination of antimony by FI-HG was developed in which stibine (SbH₃) was generated from the reaction between antimony in the injected solution and tetrahydroborate immobilized on a strong anion-exchange resin (Amberlite IRA-400). Several samples could be injected before the column was reloaded. The LOD (3s) in 4 mol l⁻¹ HCl and 10% cysteine, and 4 mol l⁻¹ HCl and 10% thiourea, were 0.55 and 0.54 μg l⁻¹, respectively. The precision, expressed as %RSD (n = 5), was 5.9, 4.9, 3.8, 2.6 and 1.0 for 5.0, 10.0, 20.0, 40.0 and 60.0 μg l⁻¹, respectively, in 4 mol l⁻¹ HCl and 10% (m/v) L-cysteine; and 8.1, 5.0, 1.5, 1.2 and 1.4 for the same concentrations in 4 mol l⁻¹ HCl and 10% (m/v) thiourea. The throughput was 60 h⁻¹. Interferences from transition metals and hydride-forming elements, and signal suppression due to high ionic strength, were eliminated by the addition L-cysteine or thiourea to the samples, which also allowed the acid concentration to be decreased to 0.61 mol l⁻¹. The method was evaluated by the analysis of spiked sea and well waters, for which no matrix effects were observed: the recoveries for 3.0 and 5.0 μg l⁻¹ were 102% and 110–114%, respectively.