Types of Chromatography
The various types of chromatography techniques are explained in the article below. Different types of chromatography techniques are roughly classified on the basis of the purpose for which they are used and the equipments/methods involved.
The different laboratory techniques used in the separation of mixtures are grouped under an umbrella term called chromatography. Apart from the criteria of classification of chromatography discussed in the article below, the basic criterion of categorizing chromatography is the purpose for which the process is carried out. On the basis of this criterion, the process of chromatography is classified as analytical and preparative chromatography. The former is carried out in order to measure the amount of a particular analyte in the mixture. Preparative chromatography on the other hand is used in separating components from a mixture for their further use.
Types of Chromatography
Based on the techniques being used, chromatography is broadly classified as adsorption and partition chromatography. An attempt to answer the question, how many types of chromatography are there, is made through the following article. Let us understand the various types of chromatography procedures in detail.
Adsorption Chromatography
In this type of chromatography, the chemical mixture in question need to be passed over an adsorbent bed. The different compounds present in this mixture get adsorbed on the bed at different rates. The process is mostly carried out for analytical separation. Adsorption chromatography is further divided into types such as ‘affinity’ and ‘ion-exchange’ chromatography.
Ion-exchange Chromatography
As the name suggests, ion-exchange mechanism is used to separate the analytes in this method of chromatography. It can be performed in 2 different modes, i.e. the planar and column. The separation of charged compounds like the peptides, amino acids, proteins, etc. is carried out by means of a charged stationary phase.
Affinity Chromatography
Non-covalent interaction that takes place between the analyte in question and certain molecules is the basis on which affinity chromatography works. The purification of proteins which are bound to tags is carried out with the help of affinity chromatography.
Partition Chromatography
In this type of separation technique, a mixture is separated by making use of partition of a solute between two solvents. In this process, one of the solvents is immobilized with the help of a substance present in the filter paper or column.
Gel Filtration Chromatography
This technique of chromatography is also known as gel permeation or size exclusion chromatography. Molecules of the mixture in question are separated on the basis of their size. Technically speaking, the separation is carried out on the basis of hydrodynamic diameter (size) of the molecules. Larger molecules present in the mixture are unable to enter the pores of media; therefore, these molecules are washed out quickly. The smaller molecules on the other hand take more time to elute, as they are able to enter the pores of media.
High Performance Liquid Chromatography
In this type of chromatography, the separation of compounds is carried out on the basis of their idiosyncratic polarities. The interaction of these compounds with the stationary phase of the column too is considered. The equipments required for carrying out high performance liquid chromatography include a pump (used for moving the mobile phase and analyte through the column), stationary phase and a detector. Retention time for the analyte too is provided by the detector. Depending on the strength of interactions that take place between analyte and the stationary phase, retention time varies.
Read more on:
- Paper Chromatography
- Thin Layer Chromatography The information about different types of chromatography techniques
is provided in short in the article above. Chromatography is thus, one of the important techniques used in the fields like biochemistry, biotechnology, etc. for the separation of compounds from mixtures.
