An HPLC method, different from reversed-phase chromatography, used mainly to separate high-molecular-weight samples and to determine their molecular-weight distribution. SEC, also called Gel Filtration Chromatography (GFC) or Gel Permeation Chromatography (GPC) is based on the molecular sieve effect and enables species to be separated according to their size and to a lesser extend, shape. The average time a substance spends in the pores of the packing can usually be correlated with its molecular weight.