Liquid chromatographic selectivity and retention behavior of rare-earth elements on a chelating resin having a propylenediaminetetraacetate type functional group

Abstract

A new chelating resin that has a functional group such as propylenediaminetetraacetate separated from the polymer matrix by a spacer arm (PDTA resin) was synthesized. The amount of ligand in the PDTA resin was 127 µmol g–1 as the amount of copper adsorbed on the resin. The chromatographic selectivity and retention behavior of rare-earth elements (REEs) on the PDTA resin were evaluated. A good correlation between the capacity factor for a series of REEs on the PDTA resin and the stability constant of the corresponding PDTA complexes was obtained (R2 = 0.963). The increasing flexibility of ligand caused by the spacer arm led to a good correlation between the selectivity of PDTA resin and free PDTA with REEs. The PDTA resin was applied to the column stationary phase for the ion chromatographic separation of REEs. A favorable separation of a series of REEs was achieved within 70 min using a nitric acid gradient. It was demonstrated that the chelating resin that has low ligand density and a spacer arm between ligand and base matrix was suitable as a stationary phase for liquid chromatography and ion chromatography.