Automatic potentiometric determination of uranium in the presence of organic solvents

Redox potentiometric titration of small amounts of uranium in mixed systems aqueous H3PO4 solutionorganic solvent using an automatic titrator was studied. The accuracy of the U determination strongly depends on the kind and concentration of the solvent. In determination of 0.1–0.2 mg of U in mixed phosphoric acid-organic solvent systems using ammonium vanadate as titrant, the determination accuracy decreases in the order acetone ≫ acetonitrile > nitromethane > ethanol. In the presence of acetone, 0.1 mg of U can be determined with high accuracy, which was impossible when using aqueous H3PO4 solutions. With all the organic components tested, the metrological characteristics are improved with an increase in the organic solvent content from 10 to 37 vol %.