CHROMATOGRAPHY

CHROMATOGRAPHY
Chromatography is the separation of sample components of a mixture based on differential affinity for a mobile versus a stationary phrase. separation involves two phrase.

MOBILE PHASE
The mobile phase is a liquid or gas with a mixture of substances to be separated.

STATIONARY PHASE
The stationary phase is a solid substance through which the mobile phase moves. The separation depends on chemical and physical properties of the molecules such as solubility and molecular mass.
ION EXCHANGE AND ABSORPTION CHROMATOGRAPHY
When the components are separated by ionic bonds the chromatography is ion exchange, and when the components are absorbed by stationary phase it is known as absorption chromatography.

PAPER CHROMATOGRAPHY
It is used for the separation of photosynthetic pigments, sugar or amino acids. In this type of chromatography paper is used as a stationary phase.

PROCESS
*) A mixture is dissolved in a liquid and spotted near one end of a paper strip.
*) The end of the paper nearest to spot is placed in the solvent in such a way that alcohol does not touch the spot.
*) Alcohol which moves through the paper by capillary action carrying the molecules with it, and results in the formation of bands on the paper.

DIAGRAM

TYPES

COLUMN CHROMATOGRAPHY
In column chromatography the stationary phase is a supporting phase is a supporting tube, with a paper or silica on the inner surface of the tube.

THIN LAYER CHROMATOGRAPHY (TLC) When the stationary phase is cellulose or thin silica then it is called as thin layer chromatography.
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