Ion exchange chromatography (IEX) resins are commonly used to separate molecules, such as large proteins, small nucleotides, and amino acids, depending on their charge. The functional groups in the IEX resins have charges that bind the molecules with opposite charges. The release of the molecules bound to the resin is carried out by charge displacement, via the application of an increasing concentration of a molecule of the same charge.

Cation exchange chromatography is a form of ion exchange chromatography (IEX), which is used to separate molecules according to their net surface charge. Cation exchange chromatography, more specifically, uses a negatively charged ion exchange resin with affinity for molecules having net positive surface charges. Cation exchange chromatography is used for both preparation and analysis and can separate a wide range of molecules from amino acids and nucleotides to large proteins.

There are different Cation exchangers: