**4.3 Chromatographic methods (HPLC and TLC)**

Chromatography is essentially a group of techniques for the separation of the compounds of mixtures by their continuous distribution between two phases. One of the two phases is the fixed (stationary) phase, which can be solid or a liquid supported on a solid. The other phase is a moving (mobile) phase which can be gas or a liquid that flows continuously around the stationary phase.

According to the nature of the mobile phase, chromatography is subdivided into liquid chromatography (LC) where the mobile phase is a liquid, and gas chromatography (GC) where the mobile phase is a gas [15].
