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Calcium isotopes were enriched in chromatography columns containing 18-crown-6 bound to a solid support. The solid support consisted of polystyrene divinylbenzene to which the crown was bound with a short tether of the structure -CH,OCH,-. Separation coefficients for the chemical exchange reaction ranged from 0.0021 to 0.0034 for the 44Ca-"Ca isotope pair. The presence of dimethylsulfoxide (DMSO) in the fluid phase was found to increase the separation coefficient. This increase was accompanied by additional mass transfer resistance. Higher calcium concentrations in the fluid phase also led to increased separation coefficients. Increases in calcium concentrations in the fluid phase resulted in substantial increases in separative power and reductions in theoretical stage heights and stage residence times. The calcium capacity of the column was decreased by the presence of DMSO and increased by increases in the fluid phase concentration.

Chromatographic enrichment of calcium isotopes with 18-crown-6 bound to a macroporous solid support