Gel filtration chromatography

From Freepedia

Gel filtration chromatography is a laboratory technique to separate biomolecules, including proteins, polysaccharides, nucleic acids etc, by size. The apparatus can be thought of as nothing more than a column packed with crosslinked gel in bead form. As a solution of molecules travels through the column, the smaller molecules diffuse into the beads from surrounding media, while the larger ones cannot diffuse into the gel matrix to such extent. Suffiently large molecules are completely unable to diffuse to beads so are confined to solution outside. When sample are added in solution as a zone to the top of the bed, the sample zone moves down as eluent is added to the top. The large molecules moves continuously down to the column while the small ones which diffuse into beads are delayed in their passage. As more eluent is poured through the column, the smaller molecules will find their way out. This means that the first fraction collected will have the largest molecules, and later fractions will have smaller ones. This is not to be confused with gel electrophoresis where smaller molecules travel faster than larger ones.

The diagram is often plotted with concentration of solution against elution volume.

The advantage of this method is that the various eluents can be applied without interefering with the filtration process, while preserving the biological activity of the molecules to be separated.

See also: Chromatography, gel permeation chromatography