Determination of technetium-99 in environmental samples by solvent extraction at controlled valence

Abstract

Distribution coefficients of technetium and ruthenium are determined under different conditions with CCl4, cyclohexanone, and 5% tri-isooctylamine (TIOA)/xylene. A method for analyzing99Tc in environmental samples has been developed by solvent extraction in which the valences of technetium and ruthenium are controlled with H2O2 and NaClO. Technetium and ruthenium which are oxidized to TcO 4 − and RuO 4 − by NaClO are separated by extraction with CCl4 at pH 4. The RuO 4 − is reduced to low valence and technetium is kept in the TcO 4 − state with H2O2. Technetium, ruthenium, and other nuclides are subsequently separated by solvent extraction with cyclohexanone and 5% TIOA/xylene. The decontamination of the procedure is 1.35·105 for103Ru and 1.66·105 for110mAg. The chemical yield of technetium-99 is 55%.