What is Thin-layer chromatography?

Thin-layer chromatography (TLC) separates the species of a mixture on a plate coated with a thin layer of a fine white powder, the stationary phase. Small spots of the samples are put on a pencil line near the bottom; the plate stands in a closed tank in a little solvent, the eluent, which climbs the plate and carries each species to a height that depends on the species. Colourless spots are then revealed, under ultraviolet light or with iodine vapour.