TLC can be used to compare the pigments in different plants

• step 1

  grind up several leaves from the shade-tolerant plant that is being investigated with some anhydrous sodium sulphate, then add a few drops of propanone.
• step 2

  • transfer the liquid to a test tube, add some petroleum ether and gently shake the tube.
  • 2 distinct layers will form in the liquid
  • the top layer is the pigments mixed with the petroleum ether
• step 3

  • transfer some of the liquid from the top layer into a second test tube with some anhydrous sodium sulphate.
• step 4

  • draw a horizontal pencil line near the bottom of a TLC plate
  • build up a single concentrated spot of the liquid from step 3 on the line by applying several drops and ensuring each one is dry before the next is added,
  • this is the point of origin.
• step 5

  • once the point of origin is dry, put the plate into a small gas container with some prepared solvent, enough so that the point of origin is a little above the solvent.
  • put a lid on the container and leave the plate to develop
  • as the solvent spreads up the plate, the different pigments move up with it, but at different rates, they seperate
• step 6

  • when the solvent has nearly reached the top, take the plate out and mark the solvent front (furthest point the solvent has reached) with a pencil
  • leave the plate to dry in a well-ventilated space
• step 7

  • there should be several new coloured spots on the chromatography plate between the point of origin and the solvent front.
  • there are the separated pigments.
  • you an can calculate the Rf value : Rf = distance travelled by spot / distance travelled by solvent.
  • look Rf value up in a database to identify what the pigments are.
• step 8 


  • repeat the process for the shade-intolerant plant you are investigating and compare the pigments present in the leaves.