Classification of chromatography based on the mechanism of separation

Chromatography is one of the widely used methods of separation in which the analytes to be separated are distributed between the stationary phase and mobile phase which travel on the stationary phase in a certain direction. The analytes of a sample mixture redistribute themselves between two phases by a process that may be partition, adsorption, ion exchange, or size exclusion. The stationary phase is either a solid or liquid and the mobile phase is either a liquid, gas, or a supercritical solution. The molecules are separated at different retention times as per affinity towards the stationary phase.
Below is the classification of chromatography based on the mechanism of separation.

Adsorption Chromatography:

Adsorption chromatography is the widely used chromatography technique for separation of components, it is working on the principle of adsorption in which the separation relies on the interaction of adsorbate with the adsorbent. The separation generally depends on the difference amongst the adsorption affinities of the molecules to the surface of an active solid. The three major types of adsorption chromatography are column chromatography, thin-layer chromatography (TLC), and gas-solid chromatography.

Partition Chromatography:

In this type of chromatographic technique, the compounds of the sample mixture distribute more probability in the two liquid phases caused by the difference in the partition coefficient. This relies on the molecules' distribution coefficient (Kd) and retention factor (K) using the mobile phase or liquid for stationary phases. The types of partition chromatography are the bonded-phase liquid chromatography and liquid-liquid chromatography.

Ion-Exchange Chromatography:

Ion-exchange chromatography is a kind of chromatography that separates components on the basis of charge. A column is used in the separation process that filled with a charged stationary phase on solid support, called an ion-exchange resin. The two types of ion chromatography are anion-exchange and cation-exchange

Exclusion chromatography:

Exclusion chromatography is also known as gel filtration or gel permeation chromatography, in this type of chromatography the separation of the analytes mainly depends on exclusion effects, that is the differences in molecular shape or size or charge. The mobile phase moves through a porous gel that separates the molecules according to their size.

Affinity Chromatography:

Affinity chromatography is a process in which the absorption separation based on the particular relationship between the compounds and the desired component in the ligand. It utilizes a particular interaction between a type of solute and another molecule, which is stable in the stationary phase.

Commonly asked questions on chromatography are as follows.

What is chromatography and its types?

Chromatography is a widely used separation technique to obtain pure compounds from sample mixtures. The 5 major types of chromatography include high-performance liquid chromatography, thin-layer chromatography, size exclusion chromatography, gas chromatography, and affinity chromatography.

What are the factors affecting separation in chromatography?
The flow rate of the mobile phase, the composition of the mobile phase, solvents used in the mobile phase, length of the column, nature, and composition of the stationary phase, the temperature of the column and working condition, pressure on the system, and structure, polarity, and size of the component is the factors that affecting the separation in chromatography

What is the factor responsible for the separation in column chromatography?
The differences of polarity between the solutes are responsible for the separation in column chromatography.


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