Determination of intrinsic viscosities of macromolecules and nanoparticles. Comparison of single-point and dilution procedures

The determination of the intrinsic viscosity by single-point determinations, like that based on the Solomon-Ciuta equation, have been proposed as efficient alternatives to dilution procedures. With a basis on theoretical analysis and computer simulation, we evaluate the systematic and global bias of the Solomon-Ciuta result and show how it depends on the strength of the concentration dependence of the solution viscosity (represented by the intrinsic viscosity and the Huggins constant) and the concentration of the single measured solution. We propose that an estimated Huggins constant can be employed in a corrected Solomon-Ciuta procedure, which may yield results for the intrinsic viscosity that are even more accurate than those from the Huggins extrapolation. This gives support and utility to the use of the single-point procedure when the intrinsic viscosity has to be determined for a unique concentration. We also pinpoint specific circumstances where the dilution-extrapolation procedures should be preferred. © Springer-Verlag 2008.