Chromatography is an important analytical technique used by chemists to separate and identify the compounds in a mixture.
There are a number of different types of chromatography, in What’s in a Medicine, thin layer chromatography was covered.
All the different types of chromatography rely on the equilibrium established when a compound distributes itself between two phases; one mobile and the other stationary.
Different compounds distribute themselves to different extents and so move along with the mobile phase at different speeds.
In thin layer chromatography, the stationary phase is the solid support material (often the plastic chromatography plate). The mobile phase is the solvent that rises up the plate.