Chromatography Silica

Silica gel is one of the most widely used stationary phases in chromatography, especially in thin-layer chromatography (TLC) and column chromatography. It is a porous, amorphous form of silicon dioxide (SiO₂) with a very high surface area and strong polarity due to surface silanol (–Si–OH) groups. These polar sites allow silica to interact strongly with compounds through hydrogen bonding, dipole–dipole interactions, and adsorption.
In normal-phase chromatography, silica acts as the polar stationary phase, while a relatively non-polar solvent (like hexane or ethyl acetate mixtures) is used as the mobile phase. Polar compounds interact more strongly with silica and therefore move more slowly, while non-polar compounds travel faster with the solvent.
Silica gel is preferred because it is inexpensive, chemically stable, and offers good separation efficiency. It is commonly used in organic chemistry to separate mixtures, monitor reactions, and purify compounds. Its particle size and pore structure can be adjusted to optimize separation performance.