Practical Techniques

Thin Layer Chromatography


  1. Draw a pencil line approximately 1cm from the bottom of the paper. Mark a cross and produce a concentrated spot of the compounds to be used by repeated application followed by drying.
  2. Mark a reference spot (known compound).
  3. Mark a spot of unknown substance.
  4. Place in chromatography tank; ensure that the spots are above the solvent.
  5. Cover with lid.
  6. Allow time for the solvent to run up the chromatography plate, so it reaches just below the end of the paper.
  7. Use locating agent to find spots, e.g. iodine, UV light etc.
  8. Compare the unknown compound with the reference compound.


This is a method used to heat a reaction for an extended period of time without losing gaseous reagents/products.

Useful books for revision

Revise A2 Chemistry for Salters (OCR A Level Chemistry B)
Salters (OCR) Revise A2 Chemistry