Simultaneous Analysis of SbIII, SbV and TMSb by High Performance Liquid Chromatography–Inductively Coupled Plasma–Mass Spectrometry Detection: Application to Antimony Speciation in Soil Samples

This study was conducted to develop a method for the simultaneous separation and detection of antimonite (Sb(III)), antimonate (Sb(V)) and trimethyl antinmony (TMSb) species in soils, using ultrasonic-aided citric acid extraction and high-performance liquid chromatography-inductively coupled plasma-mass spectrometry separation and detection. The extractions were performed using various chemical solutions. The separation was conducted on a PRP-X100 anion exchange column (25 cm × 4.1 mm i.d., 10 µm) using an isocratic elution program. The various factors of the elution procedure, e.g., pH, elution concentration and retention time, were optimized for the best separation of the three Sb species. It was found that two consecutive extractions using 100 mmol/L citric acid at pH 2.03 resulted in the highest extraction efficiency, 53%. The optimal elution procedure was obtained by using 200 mmol/L ammonium tartrate with 4% methanol as the mobile phase at pH 5.0. Under these conditions, the retention times for Sb(III), Sb(V) and TMSb species were 3.8, 2.1 and 6.8 min with detection limits of 0.03, 0.02 and 0.05 µg/L, respectively. Spiked recoveries for Sb(III), Sb(V) and TMSb ranged from 88 to 118%. The proposed method is reliable for antimony speciation in soil samples.