Rapid Determination of Uranium in Water Samples by Adsorptive Cathodic Stripping Voltammetry Using a Tin-Bismuth Alloy Electrode

In this work, the tin-bismuth alloy electrode (SnBiE) was used for U(VI) concentration determination for the first time. Compared to the conventional solid electrode (glassy carbon electrode and bismuth bulk electrode), the SnBiE possesses a higher hydrogen overpotential, which indicates that the tin-bismuth alloy can considerably extend the application of potentially available electrode detection systems. Combining with electrochemical behavior analysis and spectrometric measurements as well as theoretical calculation methods, the geometric structures of uranium-cupferron (N-nitrosophenylhydroxylamine) complexes have been revealed and a more detailed electrode mechanism has been proposed. The electroanalysis results show that the optimal sensitivity could be obtained by using diphenylguanidine as the auxiliary reagent. The calibration plot for U(VI) quantification was linear from 0.5 nM to 30 nM with a correlation coefficient of 0.999. In the meanwhile, a detection limit of 0.24 nM was obtained in connection with an accumulation time of 30 s, which is comparable with that of mercury analogues. The practical applications of SnBiE have been tentatively performed for the determination of UO₂²⁺ in real water samples and the results were well consistent with those by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). A very simple, convenient and cheap approach was established for the determination of UO₂²⁺ in natural water samples containing surfactants without the otherwise necessity of sample pretreatment, which drastically reduce the analysis time.