Adsorption Chromatography is based on the principle that some solid substances, which are known as adsorbent, have the power to hold molecules at their surface. This holding force is due to weak, non-ionic attractive forces of the van der Waals' and hydrogen bonding, which only occur at specific adsorption beds. These adsorbent beds can differentiate between the organic molecule (adsorbate) based on their strength of binding. As solvent (eluent) is constantly passed over the adsorbent (stationary phase) in the column, differences in the compound flow rate eventually lead to the separation of the organic mixture (analytes). The most commonly used adsorbents are silica, alumina, and carbon.
The process involved in TLC is as follows: