In the development of therapeutic proteins, aggregation is a parameter that needs careful monitoring to ensure the quality and consistency of the final biopharmaceutical drug product. Analytical ultracentrifugation (AUC) is considered to be a general biophysical tool with the ability to extract very high resolution size information about the molecules in a given sample from a simple sedimentation velocity experiment. One significant advantage of the sedimentation velocity method over other analytical techniques, is that it allows sample testing to be conducted in the exact or nearly exact liquid formulation or reconstituted liquid formulation of the therapeutic protein in the vial. This differs from other analytical techniques such as size-exclusion chromatography (SEC) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) where the sample is often diluted into an unrelated buffer system and where significant contact with extraneous materials occurs. For these reasons, sedimentation velocity studies are complementary to other standard methods, and when used in parallel can allow better characterization and qualification of the homogeneity and biophysical solution properties of therapeutic proteins.