Speciation of antimony(iii) and antimony(v) in seawater by flow injection solid phase extraction coupled with online hydride generation inductively coupled plasma mass spectrometry

Abstract

An automated low pressure flow analysis method with online columns pre-concentration/hydride generation (HG) inductively coupled plasma mass spectrometry (ICP-MS) was developed for the simultaneous determination of Sb(III) and Sb(V) in aqueous environmental samples. For this purpose a chelating resin [1,5-bis(2-pyridyl)-3-sulfophenyl methylene] thiocarbonohydrazide immobilised on aminopropyl-controlled pore glass (550 Å, PSTH-cpg) and an anion exchanger (Amberlite IRA-910) were used. A three column system was accordingly designed, using the two adsorbents in tandem, for the separation and preconcentration of the antimony species. The method was developed on the basis of selective sorption of Sb(III) on PSTH-cpg resin. After removal of Sb(III) by PSTH-cpg, Sb(V) was collected on Amberlite. The effects of chemicals and flow variables were investigated. The optimized operating conditions were: sample pH 8.4, a sample flow rate of 1.1 mL min⁻¹, an eluent flow rate of 1.3 mL min⁻¹, and an eluent 0.04% thiourea in 5% HNO₃. The relative standard deviations (n = 10) were 4.6% for Sb(III) and 3.0% for Sb(V), demonstrating a good precision for the analysis. The enrichment factors for Sb(III) and Sb(V) were 5.5 and 3.9, respectively. Detection limits (2 min sample loading time) were 0.013 µg L⁻¹ for Sb(III) and 0.021 µg L⁻¹ for Sb(V).The accuracy of the proposed method was checked with two certified reference materials (CRMs): SLRS-5 River Water and TMDA-54.4 Fortified Lake Water. Values obtained were in accordance with those reported for the certified materials. Recovery was found to be in the range of 97–105% for a suite of seawater samples collected in Málaga, Spain.