LITHIUM ISOTOPE EFFECTS IN CATION-EXCHANGE CHROMATOGRAPHY OF LITHIUM LACTATE IN WATER-DIMETHYL SULFOXIDE AND WATER-ACETONE MIXED-SOLVENT MEDIA

Lithium isotope separation by ion exchange displacement chromatography of lithium lactate in water-dimethyl sulfoxide (DMSO) and water-aceto ne mixed solvent media at 25-degrees-C was explored. In both the water -DMSO and water-acetone system, the single stage isotope separation fa ctor (S) was a convex function of the mixing ratio of the solvents in the external solution phase; S had its maximum value of 1.00254 at wat er:DMSO = 25:75 v/v and 1.00182 at water:acetone = 75:25 v/v. Strong c orrelations of S with solvent partitions between the solution and the exchanger phases were found in both systems, which was qualitatively e xplainable by considering the lithium isotope distributions between th e two phases based on the fundamental lithium isotope effects and the relative affinities of water, DMSO and acetone towards the lithium ion .