sentences:  For example, the apparent hydrodynamic radius of a typical protein domain might be 14 Å and 36 Å for the folded and unfolded forms, respectively.SEC allows the separation of these two forms, as the folded form elutes much later due to its smaller size.SEC can be used as a measure of both the size and the polydispersity of a synthesised polymer, that is, the ability to find the distribution of the sizes of polymer molecules.