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.