This technique separates out mixtures of chemicals by using their different solubilities in certain solvents. A concentrated spot of the solution to be separated is placed at one corner of a strip of paper. This is dipped in a solvent which carries the dissolved chemicals up the paper depositing them, the least soluble first, the most soluble last... If necessary, other chemicals may be used to make the spots visible e.g. Ninhydrin colours amino acids. They are identified by their colour and Rf values:
Spots may be further separated by running a different solvent at right angles to the first (two-way chromatography).