DETERMINATION OF THE VISCOMETRIC CONSTANTS FOR CHITOSAN AND THE APPLICATION OF UNIVERSAL CALIBRATION PROCEDURE IN ITS GEL-PERMEATION CHROMATOGRAPHY

The viscometric constants a and K in the Mark-Houwink equation were determined in 0.5 M acetic acid-0.5 M sodium acetate solution for chitosan fractionated by gel filtration. The weight-average molecular weight of each fraction was measured by the light-scattering method. The values obtained are a = 0.59 and K = 0.119 cm3 g-1. The molecular weights Mw and Mn for fractionated chitosan were measured by GPC. The value of Mw by GPC was much different from that by light scattering and, therefore, a universal calibration procedure was applied to the data by GPC. It was concluded that, also in the case of a cationic polysaccharide such as chitosan, the universal calibration procedure is effective for obtaining the reliable molecular weight by GPC.