| Abstract: | The role of the intrinsic viscosity η] as separation parameter in gel permeation chromatography (GPC) was studied for dextrans (from Leuconostoc mesenteroids B512) dissolved in water with deactivated silicagel (Porasil) as the column-filling material. For that purpose specific viscosities of dextran fractions eluted by GPC were measured as a function of the elution volume v. Provided that the elution volumes are corrected for zonal spreading, they are related to the intrinsic viscosities in an unambiguous way, probably reflecting a unique relationship between degree of branching and molecular weights. This was further investigated by developing an iteration method to prepare two calibration curves γ(v) and g(v), respectively, relating ln\documentclass{article}\pagestyle{empty}\begin{document}$\left {\bar \eta } \right]$\end {document} ] and InM (M is the molecular weight) to v. It required that the weight-average molecular weight M w, the number-average molecular weight M n, and the average intrinsic viscosity \documentclass{article}\pagestyle{empty}\begin{document}$\left {\bar \eta } \right]$\end {document} ] for a number of dextran samples (broad distributions) be previously known. The calibration curves found lead to consistent values of the above-mentioned averages. Moreover, they allow-establishment of the \documentclass{article}\pagestyle{empty}\begin{document}$\left {\bar \eta } \right]$\end {document} ]-M relationship over the range 5000 < M < 500,000. |
