GPC or SEC is used to determine the average molecular weight (Mn and Mw) and the polydispersity index (Mw/Mn) of a polymer material. These properties of a polymeric material have a strong influence on the material properties (physical, mechanical and processing properties). The results of a SEC measurement can therefore be useful in explaining certain physical or mechanical properties of a material specimen. Complementary to NMR and Infrared spectroscopy, SEC analysis is an excellent technique for comparing different material batches. Two systems are available, on which THF, HFIP or water can be used as mobile phase.