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General Theory about Size Exclusion Chromatography

Size Exclusion Chromatography (SEC)

Size Exclusion Chromatography (SEC), also known as Gel Permeation Chromatography (GPC), is a powerful chromatographic technique for the study of macromolecules in solution. In its simplest form it can give relative molecular weights (molar masses) of all types of macromolecules such as polymers, polysaccharides and proteins. In the more advanced instruments, using a multi-detection approach, you can fully characterize the samples to get absolute molecular weight and structural data including molecular size and conformational/branching information.

The basis of the SEC technique is the separation of macromolecules in solution according to their size (hydrodynamic volume). The sample solution is injected into a specialised liquid chromatography system containing SEC chromatography columns. The SEC columns separate the sample such that the largest molecules elute first and the smallest last. Once the macromolecules are separated, different detection technologies can be used to characterize each size fraction and obtain a rich array of data about the sample molecular weight and structure.