What is Chromatography and its types

The word ‘chromatography’ is derived from Greek word ‘Chromo’ meaning colour and ‘graphy’ meaning to measure; initially it was used to separate coloured compounds from the mixture. 

In another words It is an analytical technique used for the separation of closely related compounds from a mixture. These compounds are proteins, peptides, lipids ,amino acids, carbohydrates, vitamins and drugs.

Chromatography was discovered by Russian Botanist Tswest in 1903. He used it for separation of plant pigments for the first time.

The early methods used for the separation and purification of compounds from mixtures were labourious, ands slow. 

With passage of time and advancement in the separation techniques over years, the chromatographic technique has become to be known as used for the separation of different compounds from mixture and for their identification.

Principle of Chromatography

Chromatography is usually 

consists of two phases first a mobile phase and secondary is a stationary phase. 

1) Mobile phase is contain of a mixture of

substances (which are to be separated),

dissolved in a liquid or a gas.

2) The stationary phase is usually 

coated on a solid matrix. While the mobile phase contains liquid or a gas which passes through this solid phase (stationary phase) and gets separated. That's why association between mobile and stationary phase results in separation of compounds from mixtures.

Types of chromatography 

The association between above these phases (stationary phase and mobile phase) is often employed in the classification of chromatography e.g. partition, adsorption, ion-exchange. Further, the classification of chromatography is also based either on the nature of the stationary phase (paper, thin layer, column), or on the nature of both mobile and stationary phases (gas-liquid chromatography).

Partition chromatography 

In partition chromatography molecules of

a mixture is separated/partitioned between the mobile phase and stationary phase depending on the base of their relative affinity to each one of these phases.