The fundamental principle of separation by SEC was described by Benoit and coworkers in 1967. They found an excellent correlation between the elution volume and a dy- namically based molecular size, the hydrodynamic volume VH1 for a wide range of species and large-scale molecular architectures [9]. Their theory assumed a thermodynamic separation principle considering that the elution volume is independent of the flow rates. Recently, it has been proved that the radius of gyration is more appropriate than the hydrodynamic volume [10]. The radius of gyration Rg is defined as the mean square distance away from the center of gravity [11]. Its mathematical definition is: