RESUMO
Uranium (U) and plutonium (Pu) contents in nuclear materials must be maintained to a definite level in order to get the desired performance of the fuel inside the reactor. Therefore, high accuracy and precision is an essential criterion for the determination of U and Pu. We already reported the voltammetric determination of Pu in the presence of U in fast-breeder-test-reactor (FBTR) fuel samples, but interfacial, coupled chemical reactions between U(IV) and Pu(IV) enhance the peak-current density of U(VI) reduction and thus make voltammetry unsuitable for the quantitative determination of U in the presence of Pu. Thus, developing a voltammetric method for the simultaneous determination of U and Pu is highly challenging. Herein, we report the simultaneous voltammetric determination of U and Pu in 1 M sulfuric acid (H2SO4) on a poly(3,4-ethylenedioxythiophene) (PEDOT)-poly(styrenesulfonate) (PSS)-modified glassy-carbon (GC) electrode (PEDOT-PSS/GC). The modified electrode shows enhanced performance compared with bare GC electrodes. The peak-current density for U(VI) reduction is enhanced in the presence of Pu(IV), but it attains saturation when [Pu]/[U] in solution is maintained ≥2. Hence, under these circumstances, the variation of Pu concentration no longer influences the U(VI)-reduction peak, and thus the quantitative determination of U in the presence of Pu is possible. No interference is observed from commonly encountered impurities present in FBTR fuel samples. This method shows accuracy and precision comparable to those of the biamperometry method. High robustness, fast analysis, simultaneous determination, reduced radiation exposure to the analyst, and ease of recovery of U and Pu from analytical waste makes it a suitable candidate to substitute the presently applied biamperometry method.