The Fluidity One can report size (hydrodynamic radius) and concentration of a purified protein sample in solution in around 10 minutes by Microfluidic Diffusional Sizing, MDS.
The specialist buffer preparation needed for CD is not required for MDS, though samples must not contain primary amines (including TRIS buffer).
MDS is also not affected by buffer components which would be strongly scattering in CD, such as phosphate, sulphate, carbonate and acetate.
CD reports largely on secondary structure, giving a measure of the amount of protein in helices, strands and loops. In contrast the hydrodynamic radius reported by MDS provides information on the higher order elements of tertiary and quaternary structure.