Mechanism of Separation in Thin Layer Chromatography

Thin layer chromatography is another type of adsorption chromatography. Thus the basis for separation is the polarity. Polarity of the compounds in the test sample is compared with the polar stationary phase. The polar stationary phase is due to the presence of SiO₂. When consider the polarity of mobile phase, it should always be relatively less polar than the stationary phase. Thus when choosing an organic compound as a mobile phase we must be highly concern of the polarity of the organic solvent.

The glass solid support or Al solid support is applied with thin slurry of the SiO₂ and the test sample is spotted at the base line. This spot of the test sample should be a very concentrated but a minute one! With the rise of the mobile phase the spotted test sample is move up wards. Polar substances of the test sample are interacted with the stationary phase and travel slowly along the solid support. Less polar substances travel faster with the solvent.