Thin layer chromatography of three analgesics and caffeine under U.V. light was carried out in order to show the separation taking place. It is not a recommended technique in the laboratory.
Due to the nature of the uv hazard polycarbonate safety spectacles (which absorb short wavelength U.V. light) and rubber gloves were worn throughout.
Five samples were run on a single TLC plate.
The samples were (left to right on the plate):
IBU = Ibuprofen
CAF = caffeine
u? = a commercial ‘pain relief’ medicine, used as an unknown
PAR = paracetamol
ASP = aspirin
The samples were dissolved in ethanol for spotting onto the plate. The TLC plate was run in an open beaker under short wavelength u.v. light using ethyl ethanoate as the eluting solvent.
The movement of the dark purple spots (samples) during the running of the plate can be observed in the animation. The original movie can be viewed here.
It is easy to see which are the two active ingredients in the commercial pain relief medicine by comparison of the spots with the standard reference materials running on either side.
This kind of thin layer chromatography experiment is often carried out at school.