Size exclusion chromatography SEC and gel permeation chromatography GPC are essentially the same technique, with the primary difference being the type of samples they are used to analyze. Both techniques are used for the separation and characterization of polymers based on their size hydrodynamic volume in solution.Size exclusion chromatography is a more general term that can be applied to the separation of various types of macromolecules, including proteins, nucleic acids, and synthetic polymers. In SEC, the sample is passed through a column packed with porous beads, and the separation is based on the size of the molecules in solution. Larger molecules are excluded from entering the pores and elute from the column faster, while smaller molecules can enter the pores and take longer to elute.Gel permeation chromatography is a specific type of size exclusion chromatography that is used primarily for the analysis of synthetic polymers. The term "gel permeation" refers to the porous gel matrix used in the column, which is typically composed of cross-linked polymers like poly styrene-divinylbenzene or poly methyl methacrylate . The separation principle in GPC is the same as in SEC, with larger polymer molecules eluting faster than smaller ones.Both SEC and GPC are well-suited for determining the molecular weight distribution of a polymer sample. However, GPC is more commonly used for this purpose because it is specifically designed for the analysis of synthetic polymers. The columns and eluents used in GPC are tailored to the properties of synthetic polymers, which allows for more accurate and reproducible measurements of molecular weight distribution.In summary, size exclusion chromatography and gel permeation chromatography are essentially the same technique, with GPC being a specific type of SEC used for the analysis of synthetic polymers. Both methods can be used to determine the molecular weight distribution of a polymer sample, but GPC is more commonly used due to its specificity for synthetic polymers and the tailored columns and eluents used in the technique.