Size Exclusion (SEC) is the general name for the chromotographic mode also referred to as gel permeation chromatography (GPC) for non-aqueous elution systems or gel filtration chromatography (GFC) for aqueous systems.
SEC is a method in which components of a mixture are separated according to their molecular size. Large biomolecules that cannot penetrate the pores of the packing material elute first and flow with the mobile phase in the interparticle space of the packed column.
Smaller molecules can partially or completely enter the stationary phase and will elute from the column after the excluded sample components.
SEC is a very simple method for separating biomolecules, because it is not necessary to change the composition of the mobile phase during elution. However, the separation capacity of this method is limited.