The general chromatographic method was introduced into biology by Tswett in 1906 and various adsorbants such as starch and aluminium oxide are poured as a slurry into a long glass tube. An unknown compound is then poured on the open top of the tube and identified by slowly trickling down an appropriate solvent through the long tube commonly spoken of as a column. The rate at which any compound migrates through the column depends upon the balance between its affinity for the solvent and its adsorption on the particles in the column. This is generally referred to as column chromatography or adsorption chromatography. 

In column chromatography, a solid material is used to concentration of adsorb a dissolved substance out of solution. Adsorption is the increased a substance at the surface of the solid. The mechanism of adsorption depends on the attractive forces of atoms and molecules at the surface of the solid. Physical adsorption depends on van der Waals' forces and is easily decreased by lowering the concentration. Chemisorption involves actual bond formation and, hence, is not so readily decreased by lowering the concentration. More heat is evolved in chemisorption. If the solvent containing the mixture to be separated is passed over the solid in the column, then each component in the mixture establishes an equilibrium between the adsorbed and dissolved phases. The adsorbed/dissolved ratio depends on the adsorption coefficient of that substance and is referred to as 'adsorption isotherm. A molecule that is adsorbed more strongly will migrate very slowly in comparison to another molecule which is poorly adsorbed.