Thin layer chromatography
Thin layer chromatography (TLC) is a commonly used technique as it is a cheap and quick way of seperating mixtures and analysing their purity. TLC is most commonly carried out using a silica plate, with the silica acting as the stationary phase for the separation. The method involves dotting small amounts of the mixture to be analysed onto the sheet, usually about 2cm from the base on a pencil line mark. This sheet is then placed in a jar containing some solvent (elutant) that is just over 1cm in depth. The dotted mixtures must not be submerged in the elutant. This solvent is the mobile phase of the separation. A lid is placed on the container and the separation is left to run until the solvent nears the top of the TLC sheet. The exact point which the solute reached is marked with pencil so that the retention factor values can be calculated. This helps identify substances present in mixtures.
Reach Devices, 2010. Thin Layer Chromatography: How to? Available at:http://www.reachdevices.com/TLC.html