Size Exclusion Chromatography:

This separation method originated in 1959 at the Biochemical Institute in Uppsala, Sweden. Initially it was applied for the separation of water-soluble macromolecules of biological importance. The method was named as gel-filtration chromatography (GFC). A few years later the technique was developed for synthetic polymers soluble in organic solvents and it is was called as gel permeation chromatography (GPC).

This amounts to the fact that initially the names such as gel filtration chromatography (mobile phase is water) used by biochemist and gel permeation chromatography (mobile phase in organic solvent) used by polymer chemists described the technique. Now the recommended or the most accepted name of the technique is size exclusion chromatography (SEC). That is used within open column gravity fed for both analytical and preparative separations and in high performance separations. The gel filtration also finds use in thin layer chromatography and the technique is known as thin layer gel filtration chromatography. Reference to gels would also be made in Unit 12 on electrophoresis.

This unit on size exclusion chromatography first discusses the principle involved in separations using gels. This is followed through a common discussion on gels and characteristics required for the gels to be useful for chromatography. After explaining about the characteristics of gels needed for chromatographic purposes, a classification of important types of chromatographic gels is given. Along with this the methods of preparation of the important categories of these gels on a broad basis are discussed and the properties shown by them are highlighted. A brief note on the characteristics which define the utility of a gel is also included. The unique features of this form of chromatography are explained. At last, some of the important applications of the technique are discussed.

Objectives

After studying this Unit, you should be able to

• Describes the principle responsible for separation of solutes,
• Define gels and the characteristics required for their use for chromatographic separations,
• Elaborate about the classification of gels, their method of preparation and important properties of the different classes,
• enumerate the variables that define the utility of a gel,
• Provide the unique features of this chromatographic technique, and
• Cite a few of the important applications of this method of separation.