Chromatography and adsorption work by the same principle of differential adsorption of species to a surface from a complex chemical mixture. They are known to have high selectivity and can be used for separate components with closely similar physical and chemical properties. Chromatographic techniques can be used to measure a wide variety of thermodynamic, kinetic, and physico-chemical properties. Traditionally, a chromatographic column contains a stationary phase, may be a packed bed of solid particles or a liquid with which the packing is impregnated. Then the mixture to be separated is carried in the column dissolved in a gas or liquid stream called the mobile phase, eluent, or a carrier. Separation occurs because of the differing distribution coefficients of the components in the mobile and and stationary phases resulting in differing velocities of travel. This is known as elution chromatography. This is commonly used chromatographic separation and is described in this chapter. In elution chromatograph, a batch of feed mixture along with the eluent is introduced into the column inlet. The mobile phase causes the band of feed to migrate and split progressively into its component solute-bands or peaks as shown in Figure 9.1. The figure showing these solute-bands is known as a chromatogram (left side of Figure 9.1).