Field-based speciation of inorganic SB using ion-exchange resin cartridge and ICP-MS detection

Abstract

A field-based speciation method of inorganic Sb in environmental water samples is proposed using ion-exchange resin separation and determination by inductively coupled plasma mass spectrometry (ICP-MS). The problem of chemical species alteration, which occurs after the water is sampled and stored, then separated using a laboratory-based method, was solved successfully. The water samples pass directly through an ion-exchange column cartridge on-site, and then the separated solutions are analyzed by ICP-MS in the laboratory. Two promising ion-exchange cartridge columns were evaluated for the effective separation of Sb(V) and Sb(III): i) a strong cation-exchange (SCX) column, on which all Sb(III) is retained, while only Sb(V) passes to the effluent, and ii) a strong anion-exchange (SAX) column, on which both Sb(V) and Sb(III) are retained, but only Sb(V) is eluted when 12% HNO3 is used. The two Sb species can be separated efficiently using the SCX and SAX columns in the pH range of 4–10 and 6–7, respectively. The limits of detection (LODs) for Sb(V) were 0.03 and 0.05μg L-1 with the SCX and SAX methods, respectively. The repeatability, expressed as the relative standard deviation, was determined as 1.2–5.3% for the SCX column and 4.6–9.3% for the SAX column for two groundwater samples. The recoveries for Sb(V) with spiked samples ranged from 91% to 103% for the SCX method and 85% to 120% for the SAX method. The coexisting ion interference experiments showed that the SCX method has a stronger matrix tolerance than the SAX method. Ten natural water samples (two river water, five spring water, and three well water samples), collected from proposed SCX method. The results show that the dominant species in all samples was Sb(V) (64–12016 µg L−1), followed by Sb(III) (