The molecular size profile of a protein / peptide mixture is determined by SEC-HPLC / UPLC (Size exclusion).
It is a technique that separates proteins / peptides according to their molecular size.
The devices used are: Alliance from Waters and Ultimate 3000 from Dionex. These devices are equipped with UV / Fluo / RI detectors.
Other chromatographic separation techniques may be applied: reverse phase, ion exchange, etc.