SAPS - TLC - Scottish Highers This practical was developed for the Scottish Highers and is in the appropriate format. An illustrated worksheet, technical notes and students' questions are available to download at Student Sheet 10.
The pigments in leaves absorb light energy and convert it to chemical energy. This energy is transferred to and trapped inside chemicals such as glucose and starch.
Several different pigments are involved in the absorption of light. This experiment shows how these pigments can be extracted from plants and then separated.
Chromatography is a method used to separate chemically similar substances. Once the separation is complete, a chromatogram is formed.
The distance that a pigment travels over the thin layer plate depends on two factors:
a) the solubility of that pigment in each of the chemicals in the solvent. The more soluble a pigment the greater the distance it will travel.
b) the adsorption of the pigment to the thin layer plate. The more strongly a pigment is adsorbed to the silica of the plate the more slowly it will travel.
Download the full protocol from the link on the right.