chromatography

What is the purpose of chromatography?

• To separate different components in their sample

State the factors affecting the rate of migration of different pigments

• Solubility

• Mass

• Affinity to the paper

What is the formula of the RF value?

Distance moved by pigments/distance moved by solvent

What is the purpose of finding that are rough value of a pigment?

• Experimental RF value can be compared to standard value in the database to identify the pigment

What is meant by the mobile phase

• Where the molecule can move in both paper

• The mobile face is a liquid soften such as ethanol or water

What is meant by the stationary phase?

• Where the molecules can’t move

• In paper chromatography, the stationary face is a piece of chromatography paper

• Thin layer chromatography the stationary phase is a thin layer of solid

What safety precautions must do to carry out this experiment?

• Wear gloves (this will prevent amino acid from your skin getting on the chromatography paper)

• Goggles

Outline the procedure of using chromatography to separate amino acids

• Draw a pencil line near the bottom of a piece of chromatography paper and put a concentrated spot of the mixture of amino acids on it

• Add a small amount of prepared solvent to a beaker and dip the bottom of the paper(this should be done in a few cupboard) and put the lid o. The beaker

• When the solvents nearly reached the top, take the paper out and mark the solvent front with the pencil then leave it to dry

• Spray the paper with ninhydrin solution to turn the amino acids purple

Describe how the students could use thin layer chromatography to identify the pigments present in the mixture?