Separation of Lanthanides by High-Speed Countercurrent Chromatography with Organophosphate Ester

Abstract

High-speed countercurrent chromatography is a recently developed separation method that has been remarkably improved in both separating efficiency and separation time. In this paper, this advanced countercurrent chromatographic method was applied to the separation of lanthanides. In combination with the measurement of the partition coefficient of lanthanides, a suitable solvent system was chosen. The separation of a mixture containing the trivalent lanthanides La, Ce, Pr and Nd was performed with 0.15M P₅₀₇(2-ethylhexyl-2-ethylhexyl hydrogen phosphate) chloroform : hydrochloric acid, pH=2.93, (1:1, V/V) solvent system. The resolution of adjacent bands was enhanced with increasing rotational speed, and was reduced with increasing flow rate of the mobile phase. This enhancement resulted from an increasing number of theoretical plates. Mutual separation of adjacent lanthanides was accomplished with adequate resolution.