Quantification of cadmium, rhenium and thallium in low-content samples via isotope dilution ICP-MS combined with single-step anion exchange preconcentration

Abstract

Cadmium (Cd), rhenium (Re) and thallium (Tl) are dispersed metals that serve as geochemical tracers for various geological and environmental processes. Both Cd and Tl exhibit high toxicity and slow metabolic clearance rates, posing risks to plants, animals, and humans. Determining their concentrations in natural samples is challenging due to their low abundance, especially in water samples where concentrations are typically in the range of ng L⁻¹ to μg L⁻¹. In this study, we developed a simple, efficient and robust method for the simultaneous separation and quantification of Cd, Re and Tl from a single sample aliquot using an anion exchange resin. Concentrations were subsequently measured by isotope dilution (ID) inductively coupled plasma mass spectrometry (ICP-MS). The validity of this method was demonstrated through repeated analysis of reference materials BHVO-2, BIR-1a and GBW07105 (GSR-3). The results are consistent with previously published values within errors, including precision and accuracy. Additionally, the standard deviations of our concentration measurements are less than 1.49% for Cd, 3.83% for Re, and 1.63% for Tl in in-house water samples. The optimized approach was applied to river samples collected from the Pearl River tributaries. These investigations demonstrate that our sample purification and ID-ICP-MS measurement methods are effective for the quantitative determination of Cd, Re, and Tl concentrations in both rock and river samples. Our study enhances understanding of the aquatic geochemistry of Cd, Re, and Tl, thereby enhancing our ability to predict trace-element dynamics in hydrosystems.