Simultaneous speciation of selenium and mercury in human urine samples from long-term mercury-exposed populations with supplementation of selenium-enriched yeast by HPLC-ICP-MS

Abstract

The present study was carried out to establish a method for simultaneous speciation analysis of selenium and mercury. Batch-wise elution using two different mobile phases that are suitable for selenium and mercury speciation leads to successful determination of both selenium and mercury standards in 30 minutes with good efficiency and resolution. The detection limits are in the range of 0.05–0.3 μg L⁻¹ for selenium species, except TMSe, which has a poorer detection limit (1.48 μg L⁻¹), and 2.5 μg L⁻¹ for inorganic mercury (Hg²⁺) and 2.0 μg L⁻¹ for organic mercury (CH₃Hg⁺). The method was applied to analysis of urine samples from people who were long-term mercury exposed and supplemented with selenium-enriched yeast for 90 days. Selenocystine (SeCys) was found to be a major selenium form, while inorganic mercury is the major mercury form. The recoveries of spiked species were between 93 and 117% in all cases. The increased mercury concentrations in urine after 90-day selenium supplementation suggest that selenium is beneficial to the excretion of mercury from urine. The proposed technique may help to increase our understanding of the in vivo interaction between selenium and mercury in human body.