Size Exclusion Chromatography (SEC)
Size exclusion chromatography (SEC) is a liquid chromatographic technique in which particles are separated based on their size, or hydrodynamic volume. Particles of different size elute at different rates through the column, the larger eluting first. SEC is a particularly useful technique for large molecules, such as proteins and polymers. Since SEC measures hydrodynamic volume, rather than molecular weight, it may be used to assess the tertiary structure of a protein. SEC will differentiate between proteins with the same sequence/molecular weight, but with different molecular size due to variations in folding.
This may be used as a comparative technique in batch release. It is a recommended technique in the ICH Q6B guidelines for assessment of molecular weight or size, and also for liquid chromatographic patterns.