Size exclusion chromatography (SEC) is a chromatographic technique for the characterization of proteins and biopharmaceuticals, as well as natural and synthetic polymers. Traditional systems comprised a single concentration detector (Conventional Calibration), however relied upon the availability of suitable standards for the calculation of molecular weight and molecular weight distribution. Modern systems are now based on light scattering, using either the RALS/LALS single angle or the MALS (multi-angle) approach.  When the light scattering detector is coupled with one or more concentration detectors and optionally a viscometer detector in a multi-detection SEC system, it is possible to determine absolute molecular weight, molecular size, intrinsic viscosity, molecular structure, conformation, aggregation and branching, without the need for column calibrations.

This presentation compares SEC-MALS with other light scattering methods for protein and polymer molecular characterization, and give insight into the most suitable choice of light scattering detector for particular types of sample and application. Molecular weight, size and structural data acquired from the new SEC-MALS 20 and other Malvern instruments will be shown.