Rapid determination of Hg isotopes in low concentration water samples by flow injection-plasma electrochemical vapor generation

Abstract

A new strategy for determining the Hg isotopes in low Hg concentration samples is proposed, utilizing the flow injection plasma electrochemical vapor generation (FI-PEVG) sampling technique coupled with MC-ICPMS. Our study reveals that PEVG technology not only offers superior sensitivity compared to that achieved by conventional cold vapor generation (CVG), but also reduces potential interferences/contaminations arising from reagents as it avoids the use of SnCl₂, thus greatly facilitating the analysis of low content samples. By integrating with the FI technique, we can decrease the required sample volume to 0.15 mL (1.5 ng) and shorten the analysis time to just 150 s, resulting in significant reductions in sample consumption and analysis time. Different parameters affecting Hg isotope measurements were optimized, and the linear regression slope method was selected to process the transient Hg isotope signals. Under the optimized conditions, the δ²⁰²Hg and Δ¹⁹⁹Hg values achieved a precision of 0.05‰ and 0.04‰ (SD, n = 33), respectively. The efficacy of our strategy is demonstrated by analyzing spiked natural water samples and two reference materials (GBW 08617 and GBW(E) 080124). Although a small number of low Hg concentration samples have been analyzed in this study, it is believed that the proposed method provides a promising rapid and sensitive approach for accurate Hg isotope analysis of low-content samples.