Determination of antimony, bismuth and tin in natural waters by flow injection solid phase extraction coupled with online hydride generation inductively coupled plasma mass spectrometry

Abstract

A method was developed for the simultaneous separation, preconcentration and determination of antimony, bismuth and tin by flow injection solid phase extraction coupled with on-line hydride generation inductively coupled plasma mass spectrometry. The system is based on cationic retention of the analytes onto a mini-column filled with silica gel functionalised with 1,5-bis(di-2-pyridyl) methylene thiocarbonohydrazide placed in the injection valve of a simple flow manifold. The effects of chemicals and flow variables were investigated. The optimized operating conditions selected were: sample pH 3.5, sample flow rate 1.9 mL min⁻¹, eluent flow rate 0.5 mL min⁻¹, eluent 4% HNO₃ and also 0.75% L-cysteine was added directly to the standard and sample solutions. The relative standard deviations (n = 10) were 1.4% for Sb, 1.1% for Bi and 1.5% for Sn. The enrichment factors were 7.0, 8.6 and 2.5 for Sb, Bi and Sn, respectively. Detection limits (3 min sample loading time) were 0.011 μg L⁻¹ for Sb, 0.002 μg L⁻¹ for Bi and 0.142 μg L⁻¹ for Sn. The accuracy of the proposed method was checked with two certified reference materials (CRMs) of natural water TMDA-54.4 and TM-24.3. The results obtained using this method were in good agreement with the certified values of standard reference materials. The recoveries for the method when applied to determine traces of analytes in seawater were 97.0–107.5%.