practicals

• 1. Use a pencil to draw a horizontal line near the bottom of the chromatography paper.
  2. Place samples of known food colourings (A-D) next to an unknown substance (X) on this ‘start line’.
  3. Place the paper in a beaker containing a small volume of solvent.
  4. Let the solvent move to a few cm below the end of the paper.
  5. By comparing spots produced by X with those produced by A-D, you will be able to identify the unknown substance.