Simultaneous speciation analysis of As, Sb and Se redox couples by SF-ICP-MS coupled to HPLC

Abstract

A new method was developed for the simultaneous speciation analysis of inorganic arsenic (III, V), antimony (III, V) and selenium (IV, VI) in fluid samples by double-focusing sector field-inductively coupled plasma-mass spectrometry (SF-ICP-MS) coupled with high performance liquid chromatography (HPLC). A Hamilton PRX-X100 anion exchange column with EDTA (pH of 4.7) and 3% methanol as mobile phase was used for separation of the six species. The flow rate was set at 1.5 mL min⁻¹. The overall analysis time was shortened down to within 11 minutes for all six desired species after a solvent gradient (linear ramp from 5 mM to 30 mM) was introduced in. The detection limits for As(III), As(V), Sb(III), Sb(V), Se(VI) and Se(IV) were 0.02 μg L⁻¹, 0.06 μg L⁻¹, 0.2 μg L⁻¹, 0.02 μg L⁻¹, 0.2 μg L⁻¹ and 0.4 μg L⁻¹ respectively, which were obtained from 11 replicate measurements of blank. The stability of retention time and linearity of calibration curve were also evaluated. Relative standard deviations (RSD) of ≤9% for retention times (at least 20 replicate measurements) and correlation coefficients (R²) of ≥0.9998 for calibration curves (at least 6 replicate experiments) were obtained. Finally, the proposed method was applied to the analysis of one synthetic sample, two hot spring samples and two certified reference materials. The results showed a good spike recovery, indicating that basically no mass loss occurred during chromatographic separation. For two certified reference materials, the detected results were in good agreement with the certified values.