Comparatively Speaking: GLC vs. GPC

By: Anthony J. O'Lenick Jr., Siltech LLC

Posted: December 13, 2010

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Gel permeation chromatography (GPC), also called gel exclusion chromatography is a chromatographic technique that separates molecules by their size, rather than the solubility of the compound being analyzed in a solvent on the stationary phase. The GPC analysis is accomplished by passing a solution of the polymer through a porous stationary phase. Larger molecules are excluded from penetrating the stationary phase, while smaller ones penetrate the porous stationary phase, remaining within them for some time.

If the mixture contains molecules that are too small, it may be retained and not seen. There is a limited range of molecular weights that can be separated by each column; therefore, the size of the pores for the packing should be chosen according to the range of molecular weight of compounds to be separated.