What are the exclusion limit and permeation limit in size-exclusion chromatography (SEC)?

Because of the difference in pore dimeters, each size exclusion column has a range of molecular weights that can be separated. In SEC, the exclusion limit is the molecular weight at the upper limit of a column’s working range, beyond which molecules are too large to get trapped in the stationary phase and will elute together in the void volume of the column. Many SEC packings are referred to by their exclusion limit.

Meanwhile, the lower limit of the working range is defined as the permeation limit, which is the molecular weight that is small enough to penetrate all pores of the stationary phase. Molecules below this molecular weight elute in a single band in the end of elution.