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  • Author or Editor: B. Fourest x
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Abstract  

The capillary electrophoresis method has been applied to the speciation study of uranium(VI) at room temperature, in 0.02M citrate buffer solutions, at pH values between 2.5 and 5.5 and at citrate/U ratios between 20 and 40. No negatively charged species have been pointed out at pH values lower than 3. For a pH value higher than 5, the electropherograms are ill-defined and the signals cannot be analyzed simply (owing to a high and rough baseline). In the pH range 3–5, up to 4 peaks can be attributed to U(VI) species. Two of them are likely due to the expected monomer [(UO2)(Cit)]and dimer [(UO2)2(Cit)2]2− complex species and these species are shown to be in quasi-equilibrium with two other species possessing slightly lower migration velocities, [(UO2)H(Cit)(OH)] and [(UO2)2H2(Cit)2(OH)2]2−, respectively. Speciation diagrams calculated by an exact analytical approach are proposed in order to explain the experimental results. A complete agreement between theoretical and experimental results needs to take into account kinetic and hydrolysis effects.

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Abstract  

The capillary electrophoresis method with direct UV detection is proposed for the determination of nitrite and nitrate in high-salt perchlorate solutions issued from uranium carbide dissolution. The isotachophoretic sample stacking was used to compensate for the perchlorate matrix interference. Simple electrolyte composed of 120 mM formiate buffer, pH 3.8 enabled the nitrate and nitrite determination in the presence of up to 1000-fold excess of perchlorate with 2 µM and 4 µM detection limits for nitrate and nitrite, respectively. The proposed method was applied to the determination of nitrate and nitrite in high-salt non-irradiated uranium carbide dissolution samples.

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Abstract  

The advantages of the capillary electrophoresis method, known to be highly selective, have been tested on some standard latex colloids and nanoparticles of thorium phosphate, investigated separately or in mixtures. The results have been compared to those obtained by laser Doppler velocimetry. Both methods appear as complementary: capillary electrophoresis is more efficient to point out very fine particles among others, but is more restricting about the supporting medium.

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