Thin layer chromatography is used to separate a non-volatile sample. After the sample has been applied on the thin layer plate the solvent mixture is drawn up the plate by capillary action. Due to different interactions between the sample and the plate, the sample is separated into its different components. Some of the components can’t be seen with visible light and need to be projected by ultraviolet light. The illumination with UV light causes fluorescence and makes the spots visible. The different components can now be identified or quantified.
Thin layer chromatography is a very quick and simple method to determine the purity of a sample or to control a chemical process.