Ion-Exchange Chromatography

Charged analytes can be separated by ion-exchange chromatography, or IEC, where the solid stationary phase is a crosslinked polymer resin with ionic functional groups.

These resins can be strong-acid cation exchangers, weak-acid cation exchangers, weak-base anion exchangers, or strong-base anion exchangers.

While cation-exchange resins may have sulfonic or carboxylic acid groups at the exchange sites, anion-exchange resins may contain amine or quaternary ammonium groups.

The covalently attached charges have counterions that can be displaced by charged analytes.

Here, the mobile phase is an aqueous buffer whose pH and ionic composition determine the retention time of the analyte.

In general, analytes with longer retention times have higher charges, smaller hydrated radii, and higher polarizability.

IEC is a versatile separation technique with applications in water analysis and biochemistry.