Definition:

Chromatography is a method of separation in which the components to be separated are distributed among two phases, one of these is known as a stationary phase and the other a mobile phase which moves on the stationary phase in a definite direction. The components of a mixture redistribute themselves between two phases by a process which might be adsorption, partition, ion exchange and size exclusion. The stationary phase can be a solid or a liquid and the mobile phase a liquid, gas or a supercritical fluid. The stationary liquid is held on an inert solid support or coated on the walls of a capillary. The solid whether it is support or an active material is held in the form of a column, coated over a plate or presented as a paper. The latter two types come under the head of 2D chromatography.