STPM Biology Biological Molecules (Part 24)

Analytical Techniques – Chromatography

• Chromatography is teachnique used to separate a mixture of solute by differential movement of individual solutes through a porous medium.
• The most common chromatography technique used is paper chromatography. This technique is used for separating mixtures of proteins or mixture of plant pigments.

How to use paper chromatography to separate chlorophyll pigments?

Paper chromatography

 

• The technique is halted when solvent front reaches near the top of the filter paper. 
• The distanced moved by the solvent front and each of the pigments on the chromatogram is measured. R_f value of each component is then determined using the formula below.

• R_f value can be used to identify the components of a mixture by comparison with standard R_f values of substances.
• To separate a mixture of proteins, a two dimensional paper chromatography can be used for better separation.

  

  two dimensional paper chromatography