A novel electrooxidation vapor generation technique for the direct analysis of trace Os in ore/water samples

All electrolytic vapor generation technologies are based on cathodic reduction, but this paper focuses on how to use anodic oxidation to realize the gaseous transformation of noble metal Os. Supported by RuO₂-based dimensionally stable anode (DSA), we found that the conversion from trivalent/tetravalent Os to the OsO₄ can be carried out continuously and stably, even at the μg L^-1 level. Interestingly, there was a negative correlation between the conversion of OsO₄ and the RuO₂ content in the DSA. The decrease of oxygen absorption potential and the increase of current density suggest that the oxidation process of Os belongs to electrocatalytic behavior. The catalytic activity of the material has an obvious influence on the conversion of osmium while the formation of free radical may be crucial for the effective oxidation. Under the optimum conditions, this electrocatalytic synthesis of OsO₄ combined with ICP-MS can realize the same effect of oxidation and detection of two osmium species [Os(III) and Os(IV)]. The proposed method exhibits a low limit of detection (5 pg kg^-1), a wide linear range (0.1-100 μg L^-1) and excellent anti-interference performance, which promotes the direct analysis of total Os in real ore samples without separation. Considering the catalytic activity of OsO₄ in specific reactions, this green anodic electrosynthesis technology is also expected to provide more possibilities.