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Tuesday, June 2, 2020

Partition chromatography mechanism of action

The chromatographic technique works based on four different separation mechanisms, such as partition, adsorption, size exclusion, and ion exchange.  

What is partition chromatography?

Partition chromatography is the basic method of distribution mechanism of liquid-liquid chromatography, specifically when the stationary phase and mobile phase both are liquids. Isolation by distribution depending on the relative solubility of the component in both phases. The basic principle of partition chromatography is used in several methods, such as high-performance liquid chromatography (HPLC), paper chromatography, high-performance thin-layer chromatography (HPTLC), and gas chromatography (GC). 

Separation mechanism of partition chromatography:

The stationary liquid phase of partition chromatography is coated on solid supports such as silica gel or cellulose powder. Assuming solid supports have not adsorption, the mobile and stationary phases move the compounds through the system at rates determined by the solubility of their components. Usually, the mobile and stationary phases do not need to be entirely immiscible; however, it is ideal to have a low degree of mutual solubility. Hydrophilic stationary phase solvents are commonly used in combination with hydrophobic mobile phases, or vice versa.

Principle of partition chromatography: 

Partition chromatography is the technique of separation in which the solute present in a sample mixture distributes more possibility in two liquid phases as the differences in partition coefficients. In this method, the analytes are isolated amongst two phases i.e. both the mobile phase and the stationary phase are in the identical phase. In this process of separation, on the stationary phase, the immiscible solid surface coated with the liquid surface is in the mobile phase. The liquid surface is immobilized by a stationary phase resulting in its being a stationary phase. The mobile phase travels over the stationary phase and the analytes are separated. Consequently, the analytes are preferably dispersed at any phase.  

Different types of partition chromatography:

Liquid-liquid chromatography: In this kind of partition chromatography both phases such as stationary phase and mobile phase are taken in liquid form. However, the liquid stationary phase is supported by coated by solid supports. Its sub-types are paper chromatography, column chromatography, and thin-layer chromatography 

Gas-liquid chromatography: In this form, gas is used as a mobile phase which is unreactive, and the stationary phase is a non-volatile liquid held on an inert solid support. 


Commonly asked questions on chromatography are as follows.

What are the types of partition chromatography?
Two types of partition chromatography are available, liquid-liquid chromatography and gas-liquid chromatography.

What is partition chromatography used for?
Partition chromatography is a process used for the isolation and identification of mixtures of closely related substances such as amino acids.

What are the two main types of chromatography?
Liquid chromatography (LC) and gas chromatography (GC) are the two major types of chromatography.

What is the basic principle of paper chromatography?
The basic principle involved in paper chromatography is partition chromatography in which the solutes are partitioned or distributed between liquid phases.

Why do we use a pencil in chromatography?
The starting line in paper chromatography is drawn using a pencil, as the pencil lead will not dissolve in the mobile phase, and does not affect the separation.


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