Aqueous biphasic separation of 97Ru and 95,96Tc from yttrium

Abstract

An aqueous biphasic separation technique has been developed for the separation of ⁹⁷Ru, a potential candidate radionuclide in nuclear medicine, from its target matrix, yttrium. The extraction of ruthenium and technetium from bulk yttrium has been carried out with 50% (w/v) PEG-4000 and PEG-6000 against 2 M solution of various salts, such as Na-citrate, Na-tartarate, Na-malonate, Na₂CO₃, NaHSO₃, Na₂SO₄, Na₂S₂O₃, K₂HPO₄, K₃PO₄, (NH₄)₂SO₄ and 4 M KOH, at room temperature. The influence of the pH of some salt rich phases (e.g., Na-tartarate and (NH₄)₂SO₄) on the extraction behavior of ⁹⁷Ru and ^95,96Tc into the PEG rich phase was also studied. In the presence of Na-tartarate, Na-citrate, K₂HPO₄, K₃PO₄, KOH, Na₂CO₃, Na₂SO₄, Na₂SO₃ and (NH₄)₂SO₄ salt solutions, ⁹⁷Ru and ^95,96Tc were preferentially extracted into the PEG rich phase. In 50% (w/v) PEG-4000-2 M (NH₄)₂SO₄ ABS system, 83% of ⁹⁷Ru along with 96% of ^95,96Tc were extracted into the PEG rich phase without any contamination of the yttrium target. Back extraction of ⁹⁷Ru into the salt rich phases from the PEG rich phase was also carried out using 2 M salt solutions of K₂CO₃, Na₂S₂O₃ and 4 M KOH. About 90% back extraction of ⁹⁷Ru into the salt rich phases without any contamination of ^95,96Tc was obtained with 2 M Na₂S₂O₃ salt solution. Dialysis of the PEG rich phase containing ⁹⁷Ru along with ^95,96Tc was also carried out against deionised water to obtain pure ⁹⁷Ru.