Fig. 3 Diffusion coefficients in aqueous solutions of various viscosity. Reciprocals of obtained diffusion coefficients versus viscosity. As expected from the Einstein–Stokes equation, they were linear relationships. The results of least-squares linear regression are shown by the broken lines. For the regression, data points at 10.8 mPa s were eliminated (see text for detail). The data points and error bars indicate the mean ± s.d. (N=3).