Measurement of total antimony and antimony species in mine contaminated soils by ICPMS and HPLC-ICPMS

Abstract

This paper describes the measurement of total antimony and antimony species in “real world” mine contaminated sediments using ICPMS and HPLC-ICPMS. Low and high temperature microwave extraction procedures (90 °C and 150 °C, respectively) using a range of nitric–hydrochloric acid combinations were examined as to their efficacy to extract antimony from six mine contaminated soils and a certified reference material. The use of the higher temperature with nitric–hydrochloric acid (1 : 2 (v/v)) was suitable to release antimony from sediments and the certified reference material, NIST 2710 Montana soil. Antimony concentrations obtained using this acid mixture were similar to those obtained using a more aggressive extraction with nitric, hydrochloric, perchloric and hydrofluoric acid mixture. A 25 mM citric acid solution at 90 °C for 15 min extracted 47–78% of antimony from soils. A Hamilton PRP X-100 anion exchange column with 20 mM EDTA mobile phase, pH 4.5, flow rate 1.5 mL min^–1 and column temperature of 50 °C was used to separate antimony species. Column recoveries ranged from 78–104%. The predominant form of antimony was Sb⁵⁺. Little conversion of Sb⁵⁺ occurred (<5%) during extraction, however, significant conversion of Sb³⁺ occurred (∼36%). The extraction of antimony species with citric acid should be useful in the determination of inorganic antimony available to plants, as plants commonly excrete carboxylic acids, including citric acid, into their rhizospheres to mobilise trace elements for nutritional purposes.