Thin layer chromatography (TLC)
is a Chromatography technique used to separate mixtures.
Thin layer chromatography is performed on a sheet of glass,
plastic, or aluminum foil, which is coated with a thin layer
of adsorbent material, usually silica gel, aluminum oxide, or
cellulose (blotter paper. This layer of adsorbent is known as
the stationary phase.
After the sample has been applied on the plate, a solvent or
solvent mixture (known as the mobile phase) is drawn up
the plate via capillary action. Because different analytes
ascend the TLC plate at different rates, separation is
achieved.
Thin layer chromatography can be used to:
• Monitor the progress of a reaction
• Identify compounds present in a given substance
• Determine the purity of a substance
Thin Layer Chromatography - t.l.c.
• Series of spots forms
• Compare samples in
mixture with known
substances.
• Measure Rf values.
• Coloured compounds
& colourless
compounds.
Separation and identification.
Examples on TLC separations
1. Separation of black ink on a TLC
2. The chromatography of an extract
of green leaves (for example
spinach)
3. The Chromatogram of
10 essential oils
colored with vanillin
reagent.
Preparative TLC
• TLC can also be used on a small semi-preparative scale to
separate mixtures of up to a few hundred milligrams. The
mixture is not "spotted" on the TLC plate as dots, but rather
is applied to the plate as a thin even layer horizontally to
and just above the solvent level. When developed with
solvent the compounds separate in horizontal bands