liquid chromatography separation size-exclusion chromatography MS:1003580 MS Size-exclusion chromatography (SEC), also known as gel filtration chromatography (GFC) or gel permeation chromatography (GPC), is a chromatographic technique that separates molecules based on their size or, more precisely, their hydrodynamic volume in solution. This method is primarily used for the separation of large molecules like proteins and polymers.