Principle of Cation Exchange Chromatography

Principle of Cation Exchange Chromatography

Cation exchange chromatography is a form of ion exchange chromatography (IEX), which is used to separate molecules based on their net surface charge. Cation exchange chromatography, more specifically, uses a negatively charged ion exchange resin with an affinity for molecules having net positive surface charges

Principle

Introduction of sample which is a mixture of cations.

Exchange of ions taking place maintaining neutrality.

R-SO3- H+ -Cation Exchange Resin

Elution of H+ ions from resin.

Separated ions(Eluate)

Mobile Phase(eluant)

The cation exchange resin beads are sulfonated to give sulfonated resin beads i.e. R-SO3- H+. In this sulfonated resin the negatively charged sulfonated ions are firmly attached while H+ ions move freely and can be exchanged. When the cation mixture sample is introduced the exchange of ions take place maintaining the neutrality and the H+ ions are eluted out of the resin. The cations from the mixture gets attached to the resin. When the mobile phase(eluant) is added the cations attached to the resin will get separated out depending on their adsorption strength and will be collected in another beaker. Here the adsorption strength of cation in blue colour is less hence it will be separated out first then will be cations in red colour and at last cations in green colour will be separated.