*4.3.2 Thin-layer chromatography (TLC)*

Thin-layer chromatography has developed into a very sophisticated technique for identification of compounds and for determination of the presence of trace

impurities. Separation in TLC occurs by either adsorption or partition. For adsorption, the stationary phase consists of a thin layer of sorbent (e.g. silica) which is activated by heating at 105°C to evaporate water and the mobile phase is devoid of water (usually a mixture of organic solvents).

The term retention time used in TLC is referred to as Rf value which is the distance traveled by the compound from the origin (where the compound is spotted on the plate) divided by the distance traveled by the solvent. Although TLC is widely used for qualitative analysis, it does not in general provide quantitative information of high precision and accuracy. Changes in the practice of TLC have resulted in improved performance of separation and quantitative measurement. These developments are referred to as high-performance thin-layer chromatography (HPTLC) [24].

TLC is widely used in pharmaceutical analysis for:


d.Following synthetic reactions for their completion.

e.Forensic application in drug poisoning or addiction.
