Size Exclusion Chromatography and Related Separation Techniques

Size exclusion chromatography (SEC), often referred to as gel permation chromatography (GPC), is an entropically controlled separation technique in which molecules are separated on the basis of hydrodynamic molecular volume or size. With proper column calibation or by the use of molecular-weight-sensitive detectors, such as light scattering, viscometry, or mass spectrometry, the molecular weight distribution (MWD) and the statistical molecular weight averages can be obtained readily. Thus, SEC is the premier technique for determining these properties of both synthetic polymers and biopolymers. For this review, we have expanded coverage of related polymer separation techniques, including interactive (enthalpic) modes of HPLC, temperature-rising elution fractionation, and field-flow fractionation. Important developments in SEC have continued in the area of detection systems, mainly light scattering, viscometry, and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry in conjunction with SEC for determining MW and chemical composition of polymeric materials. An emerging technology is NMR detection, which in a few years should have a major impact as an on-line detection method for SEC and HPLC. (Article notes applications in regard to cellulosics, inorganic compounds, synthetic polymers, biopolymers, and other materials.)