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Wednesday, April 17, 2019

What are the Different Types of Chromatography

Learn the various types of chromatography techniques.

Chromatography is an analytical technique in chemistry that is based on the separation of a sample molecule in two phases, which is a mobile phase and a stationary phase. While a sample is passed with the mobile phase through a stationary phase the interactions happen between the stationary phase and the analytes or solutes, each molecule has different properties and based on the differences in these interactions they get separated. In many of its variations, chromatography is a crucial separation technique for the analysis or purification of one or several analytes in a mix that can include different types of complex components. Initially, it was developed in the form of column chromatography. But due to the limited efficiency and applications, it was modified and introduced advanced techniques of separation. Therefore, since advancement, we have many types of chromatography.


Different types of chromatography methods are available based on the points given below.
1. It depends on the principle of isolation used.
2. The physical states of the mobile and stationary phase.
3. Based on the chemical nature (Polarity) of mobile and stationary phase used.
4. As per the shape of the stationary phase.
5. Chromatography based on the purpose of the testing.
6. Depending on the chemical or physical nature of the stationary phase.


 Different types of chromatography are mentioned here:

Adsorption Chromatography:

To separate the components the adsorption chromatography is the oldest kind of chromatography, it is based on the principle of adsorption in which the separation depends on the interaction of the adsorbate with the adsorbent. In this type of chromatography, the liquid or gaseous phase (Mobile phase) is used on the surface of the solid stationary phase. The equilibration amongst the mobile phase and the stationary phase is for the separation of different solutes.
There are three main types of adsorption chromatography are thin-layer chromatography (TLC), column chromatography, and gas-solid chromatography.

Partition Chromatography:

Partition chromatography is a kind of chromatography used for the separation of components. In this type of method, the analytes present in the sample mixture distribute more probability in two liquid phases due to differences in the partition coefficient. It relies on the retention factor (K) and distribution coefficient (Kd) of the molecules using the liquid for the stationary phases. The liquid-liquid chromatography and bonded-phase liquid chromatography are types of partition chromatography.

Ion Exchange Chromatography:

Ion chromatography is an effective method for the separation of charged particles; it involves the separation of ionizable components on the basis of their total charge. Ion exchange chromatography is often executed as column chromatography. This method allows the separation of equivalent kind of analytes which will be complex to isolate by other techniques, as the charge made by the interested molecule can be easily manipulated by altering the buffer pH. Ion exchange chromatography has two types anion-exchange and cation-exchange chromatography.

Molecular Exclusion Chromatography:

It is also recognized as gel filtration or gel permeation chromatography. In this chromatography method lack an alluring interaction amongst stationary phase and molecules. The liquid/gas phase travels via a porous gel that separates the analytes as per its size. Generally, the pores are small and remove large molecules, however, it allows small analytes to enter the gel so that they flow in large quantities. This is the cause that large molecules move through a column at an accelerated rate compared to smaller ones. Two basic types of size exclusion chromatography are a gel permeation chromatography (GPC) and the second is gel filtration chromatography (GFC).

Affinity Chromatography:

It is a method in which the distinction of absorption relies on the particular relationship between the substances and the desired component in the ligand. Affinity chromatography is the mainly discriminating type of chromatography. It employs a specific interaction amongst a type of solute analyte and another analyte, which is immobilized at the stationary phase.

Some commonly used chromatography techniques are:
  • Column chromatography
  • Paper chromatography
  • Thin-layer chromatography (TLC)
  • Gas chromatography (GC)
  • High-performance liquid chromatography (HPLC)
  • Supercritical fluid chromatography
  • Gel filtration chromatography
There are various types of chromatography methods and are classified based on the separation mechanisms, the physical state of the mobile phase, and the shape of the bed.
All types of chromatography techniques work on the same principle. All of these contain a mobile phase consists of gas or liquid and a stationary phase consist of solid or liquid. The sample mixture travels through the stationary phase with the mobile phase, due to the difference in the affinities of components, they are separated.


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