23.7 What is Gel Permeation Chromatography?
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This article is from the Chemistry FAQ, by Bruce Hamilton B.Hamilton@irl.cri.nz with numerous contributions by others.
23.7 What is Gel Permeation Chromatography?
Gel Permeation chromatography ( aka Size Exclusion chromatography ) is based
on the ability of molecules to move through a column of gel that has pores of
clearly-defined sizes. The larger molecules can not enter the pores, thus
they pass quickly through the column and elute first. Slightly smaller
molecules can enter some pores, and so take longer to elute, and small
molecules can be delayed further. The great advantage of the technique is
simplicity, it is isocratic ( single solvent - no gradient programming ),
and large molecules rapidly elute. The technique can be used to determine
the molecular weight of large biomolecules and polymers, as well as
separating them from salts and small molecules. The columns are very
expensive and sensitive to contamination, consequently they are mainly used
in applications where alternative separation techniques are not available,
and sample are fairly clean. The best known columns are the Shodex
cross-linked polystyrene-divinylbenzene columns for use with organic solvents,
and polyhydroxymethacrylate gel filtration columns for use with aqueous
solvents. "Modern Size Exclusion Chromatography" [15], and Heftmann [1],
provide good overviews, and there are some good introductory booklets from
Pharmacia.
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