Oxidation of plutonium by cobalt(III) green

A stable green solution of tricarbonatocobaltate(III) has been prepared and used for the redox titrimetric determination of plutonium in HNO₃ medium. Quantitative oxidation could be achieved and excess oxidant could be destroyed by NaNO₂. Pu(VI) was deter-ined by adding known excess of Fe(II) and carrying out potentiometric titration. The precision at the level of 0.5–5.0 mg was 2% RSD.