The SLS technology measures the weight-average molecular weight of macromolecules such as polymers and proteins that are dissolved in solutions. During a SLS measurement, the instrument detects scattering intensities of particles in solutions with different concentrations. The Rayleigh ratios of samples at different concentrations were calculated and plotted against concentrations into a Debye plot. The molecular weight Mw and the second virial coefficient A2 are then obtained through the intercept and slope from the linear fitting of the Debye plot, respectively.