Take You Close To Welch Ion Exchange And HILIC Analytical Columns- Welch Materials, Inc.

Principles of Ion Exchange Chromatography

Ion exchange chromatography refers to some charged groups in the stationary phase in ion exchange chromatography that bind to oppositely charged ions through electrostatic interactions. If other oppositely charged ions are present in the mobile phase, according to the law of mass action, these ions will exchange with the oppositely charged ions bound to the stationary phase.

There are two types of stationary phases in ion exchange chromatography: cation exchange functional groups and anion exchange functional groups. The cation exchange functional group has a negative charge and is used for the separation of cations; the anion exchanger functional group has a positive charge and is used for the separation of anions. The most commonly used cation exchange functional group is sulfonate type, and the most commonly used anion exchange functional group is quaternary amine type.

The mobile phase for ion exchange chromatography is usually a buffered aqueous solution containing salt. In order to meet different separation needs, sometimes an appropriate amount of organic solvents that are compatible with water, such as methanol, acetonitrile, tetrahydrofuran, etc., are added to improve the solubility of the sample, improve selectivity, and improve separation.

In ion chromatography with aqueous solution as the mobile phase, the concentration of the buffer solution directly affects the ion balance. When the buffer concentration increases, the concentration of counter ions in the mobile phase increases, which enhances its ability to compete with sample ions for ion-exchange functional groups, thereby weakening the affinity of sample components for ion-exchange resins. The type of ions in the mobile phase has a significant effect on the retention of sample molecules.