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A novel electrochemical sensor for trace (μg/L) Uranium, based on adsorptive stripping potentiometry, is described. The sensor operation relies on the adsorptive accumulation of the uranium-cupferron complex onto a mercury-coated screen-printed carbon electrode. The disposable nature of these electrodes makes them very attractive for on-site characterization of nuclear energy sites. Various variables affecting the potentiometric stripping response were characterized and optimized to yield low-detection limit (e.g., 0.5 μg/L following a 5 minute adsorption) and good precision (relative standard deviation (RSD) = 1.4% for n = 15, 25 μg/L uranium). Convenient measurements can be carried out in nondeaerated and quiescent solutions. Applicability to the quantitation of uranium in groundwater samples is demonstrated.

A sensitive stripping voltammetric procedure for trace measurement of thorium, based on the catalytic-adsorptive peak of the thorium—cupferron complex, is reported. Optimal experimental conditions include the use of 1mM BES buffer solution (pH 5.5), containing 20μM cupferron, an accumulation potential of −0.80 V (vs. Ag/AgCl), and a differential pulse potential scan. The resulting stripping procedure offers improved sensitivity over a previous stripping scheme for thorium. The limit of detection after 5 min preconcentration is 50 ng/l. (2 × 10−10M), the response is linear up to 8 × 10−8M, and the relative standard deviation at the 2.1 × 10−8M level is 4.4%. Possible interferences are evaluated.