When oxygen is released, carbon dioxide binds to hemoglobin to be transported out of the body. Human hemoglobin contains four polypeptides, in which the tetramer equilibrates with a dimer form, depending on the conditions. Using size-exclusion chromatography (SEC) in combination with multi-angle light scattering (MALS), a miniDAWN® detector and Optilab® DSP interferometric refractometer were used for the characterization.