selectivity for monovalent over polyvalent ions increases. Ionic properties which determine resin
affinity are complex involving hydration energy, polarizability and hydrated ionic radius. The last
shows an approximately inverse relationship to the selectivity coefficient.
Ion-exchange Separations
Most separations are performed using columns of resin and an elution procedure. The sample is
introduced as a small band at the top of the column from where the various components are moved
down the column at