Voltammetric behavior of neptunium(vi) in glutamic acid media at the rotating glassy carbon electrode

The voltammetry of neptunium(VI) glutamate was investigated over the pH range 3.8–10.0. A reversible, one-electron wave was obtained for glutamate concentrations above 0.1 M in the pH range 3.8–6.1, or above 0.3 M in the pH range 6.1–10.0. At pH 3.8–6.1, the half-wave potential was independent of pH, but at pH 6.1–10.0, it was a function of pH. The metal-ligand ratio was found to be 1:2 by conductometric titration. The limiting current was proportional to the concentration of the neptunium(VI) from 7.83·10^-5 to 1.96·10^-3M. The diffusion coefficient was 0.35·10^-5 cm² sec^-1 at pH 4.5 and 0.30·10^-5 cm² sec^-1 at pH 9.4.