Optimisation of laboratory antimony measurement techniques for environmental samples

Abstract

ABSTRACT Antimony (Sb) is a redox-sensitive toxic trace metalloid that occurs just below arsenic (As) in Group 15 of the periodic table. These two elements share many geochemical and toxicological similarities. Antimony contamination is a global problem of emerging concern, particularly around mining and smelting areas where the element is actively mined and processed for a variety of industrial applications. The measurement and monitoring of Sb in drinking water and freshwater aquatic ecosystems are therefore becoming an increasing concern. Antimony measurement, however, is often analytically challenging owing to differing solubility of the element when it is present in various environmental redox states. The element is also very susceptible to precipitation from solution due to commonly occurring matrix effects, such as the presence of co-occurring sulphide or pH variations during sample preparation. Here we evaluated three of the most commonly used methods of analysis for measurement of total Sb concentration in aqueous samples and in freshwater sediments; ICP-MS, ICP-OES and UV-Vis spectrophotometry. Methods were evaluated on the basis of analytical precision/reproducibility, cost and potential environmental hazard. Analytical results are presented both for standards and environmental test samples. Statistical analysis of results indicates that analytical reliability of these methods, ranked in order of decreasing reliability, follows the order ICP-MS, ICP-OES and UV-Vis spectrophotometric method. Rankings based on increasing order of cost and environmental hazard of reagents both follow an opposing trend of UV-Vis spectrophotometric method, ICP-OES and ICP-MS.