Editing Chromatography (section)

===Size-exclusion chromatography===
{{further|Size-exclusion chromatography}}
Size-exclusion chromatography (SEC) is also known as ''gel permeation chromatography'' (GPC) or ''gel filtration chromatography'' and separates molecules according to their size (or more accurately according to their hydrodynamic diameter or hydrodynamic volume).
Smaller molecules are able to enter the pores of the media and, therefore, molecules are trapped and removed from the flow of the mobile phase. The average residence time in the pores depends upon the effective size of the analyte molecules. However, molecules that are larger than the average pore size of the packing are excluded and thus suffer essentially no retention; such species are the first to be eluted. It is generally a low-resolution chromatography technique and thus it is often reserved for the final, "polishing" step of a purification. It is also useful for determining the [[tertiary structure]] and [[quaternary structure]] of purified proteins, especially since it can be carried out under native solution conditions.