Chromatography

• can be used to separate and identify mixtures of amino acids. Amino acids are colourless but appear as purple spots on the paper when sprayed with a locating agent and dried
• always involves a mobile and stationary phase.
• The mobile phase moves through the stationary phase, carrying components of the mixture.
• Each component in the mixture will have a different attraction for the mobile and the stationary phase.
• A substance with a stronger force of attraction between itself and the mobile phase than between itself and the stationary phase will be carried a greater distance.
• In paper chromatography, the mobile phase is the solvent and the stationary phase is the paper.
• The retention factor (Rf) is a ratio calculated by dividing the distance a spot travels up the paper by the distance travelled by the solvent.

  -> Rf = distance moved by substance / distance moved by solvent