Effect of Temperature and the Mechanism of Zone Spreading During Cation-Exchange Separation of Rare Earth Elements by Ion Chromatography

Separation of rare earth elements (REE) by ion chromatography on a Dionex Ion Pac CS3 column (sulfonic acid type) has been studied at different temperatures (10–70 °C) and with both isocratic and gradient elution with α-hydroxyisobutyric acid (α-HIBA). Changes of column efficiency as a function of distribution coefficient and temperature could not be explained on the basis of classical Van Deemter or Glueckauf-Hamilton equations and possible explanation indicating the contribution of longitudinal diffusion in the resin phase to total zone spreading was provided. It was shown that the plate height for yttrium was distinctly smaller that those for lanthanides of similar ionic radii. An improved combined isocratic-gradient elution procedure was devised for separation of Sc, Y, La, and the lanthanides in one run.