An experiment to identify substance X using thin layer chromatography.

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An experiment to identify substance X using thin layer chromatography.


In this experiment the method being used is chromatography.  Chromatography is an important method for finding out more about mixtures.  Chromatography allows substances to be separated with a solvent and indicates whether a substance is pure, meaning it contains only one single substance, as opposed to a mixture of substances, allowing for concentrations to be made.  By using think layer chromatography (TLC), the aim of the experiment is to find out whether ‘substance X’ is either Anadin which contains aspirin and caffeine, or Anadin extra, which contains aspirin, caffeine and also paracetamol.  Thin layer chromatography is a technique involving the distribution of a mixture of two or more substances between a stationary phase (involving a solid or a liquid) and a mobile phase (involving a solid or a gas).  The thin layer of absorbent coated on the chromatography paper is normally a silica get, cellulose or alumina.  The mobile phase is a developing liquid.  The developing liquid (Butyl Ethanolate), travels up the stationary phase, moving the samples with it, in this case over the counter analgesics.  The samples will separate on the stationary phase according to how much they absorb on the stationary phase against how much they dissolve in the mobile phase.

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It is to be expected that substance x will be able to be identified using thin layer chromatography.

Safety assessment


  1. A strip of chromatography paper was taken and a thin pencil line was made at the bottom of the paper – three equally spaced marks were also made, ensuring that the paper was not touched.
  2. Four test tubes were taken and labeled A(aspirin), P(paracetamol), C(caffeine) and X(substance X)
  3. 1-2cm³ of the drug solvent (Ethanol) was added to each tube.  Then carefully shaken from side to side, to ensure the drug samples were ...

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