Affinity Chromatography

The stationary phase of this chromatographic technique is a gel matrix. And the mobile phase is a buffered solution.

The blue arrows on the stationary phase are capable of attaching to their specific compounds those coming with the mobile phase. According to the theory of this technique, the shape of the compounds in blue color matches perfectly to the shape of the arrow head. Thus they are bound well to the stationary phase taking longer period to elute where as other compounds (yellow and dark blue) elute first. Thus the interaction is between one type of solute molecule in the test sample and the substance in the stationary phase (blue arrow).This reaction is a covalent interaction.

This is mainly used in antibody testing assays. Test sample contains a mixture of proteins and immobilized molecule is an antibody to some specific protein. Only the specific protein is reacted to this antibody in the stationary phase. And this particular protein is extracted by changing the pH of the mobile phase. This extraction is done by weakening the covalent bonds of the two substances involved in the interaction.