Column Chromatography is based on the principle of differential adsorption.

• Stationary Phase: A porous material with a large surface area, known as an Adsorbent, is packed into a vertical column. Common materials include Silica gel ($Si{O}_2$) and Alumina ($A{l}_2{O}_3$).
• Mobile Phase: An appropriate solvent (or mixture) flows down through the adsorbent.
• Separation: Different components of the mixture adsorb onto the stationary phase with varying strengths. The less strongly adsorbed components move faster and are eluted first.