Experimental Procedure for Affinity Chromatography

If ionic interactions are important for complex formation, a change in pH or ionic strength weakens the interaction by altering the extent of ionization of ligand and macromolecule. In practice, either a decrease in pH or a gradual increase in ionic strength (continual or stepwise gradient) is used. 

In this method of elution, a selective substance added to the eluting buffer competes for binding to the ligand or for binding to the adsorbed macromolecule. 

If gentle and selective elution methods do not release the bound macromolecule, then mild denaturing agents can be added to the buffer. These 

Purification of a-chy-motrypsin by affinity chromatography on immobilized D-tryptophan methyl ester. From Affinity Chromatography Principles and Methods, Pharmacia, Uppsala, Sweden. 

---