The technique of Thin Layer Chromatography (TLC) is normally used as an analytical method to follow the progress of a reaction, to analyse mixtures or to establish conditions for a preparative separation of compounds using column chromatography. The stationary phase (often silica) is coated on plastic or aluminium plates. The mixture is spotted on the plate and solvent is allowed to run up the plate to separate the compounds.

The eluotropic series

The eluotropic series lists solvents in order of their power to carry a given compound through the stationary phase (e.g. silica gel). The order of solvents runs in the order of their polarity. The series is useful when selecting a solvent for a particular separation where more polar compounds will normally require a more polar solvent. The solvent for a chromatographic separation will usually be specified in the script however a good starting point for a new separation is one with medium polarity such as dichloromethane or acetone.

High Polarity


Ethanoic Acid (Acetic Acid)




Ethanenitrile (Acetonitrile)

Ethyl Ethanoate (Ethyl Acetate)

Propanone (Acetone)



Diethyl Ether

Toluene (Methyl Benzene)



Low Polarity