Affinity chromatography is a method of separating biochemical

Biochemistry

Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...

 mixtures and based on a highly specific interaction such as that between antigen and antibody, enzyme and substrate

Substrate (biochemistry)

In biochemistry, a substrate is a molecule upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate. In the case of a single substrate, the substrate binds with the enzyme active site, and an enzyme-substrate complex is formed. The substrate is transformed into one or...

, or receptor and ligand

Ligand (biochemistry)

In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. In a narrower sense, it is a signal triggering molecule, binding to a site on a target protein.The binding occurs by intermolecular forces, such as ionic bonds, hydrogen...

.
Affinity chromatography can be used to:

• Purify and concentrate a substance from a mixture into a buffering solution
• Reduce the amount of a substance in a mixture
• Discern what biological compounds bind to a particular substance
• Purify and concentrate an enzyme solution.

The immobile phase is typically a gel matrix, often of agarose; a linear sugar molecule derived from algae.