The Fractionation of Hydrolyzed Dextran by Ultrafiltration Through A Series of Anisotropic Cellulose Acetate Membranes

Dextran, a homopolyner consisting almost solely of 1,6-α- linked glucose units, was separated into five well defined, narrow range, low molecular weight fractions by sequential ultrafiltration, after controlled lydrolysis. A commercially available purified dextran preparation, D 10, with a weight average molecular weight (Mw) of 10,980, was hydrolyzed with HCl to an average molecular weight of 4200. By ultrafiltration through a series of graded anisotropic cellulose acetate membranes of decreasing sore sizes, molecular weight fractions having Mw's of 7100, 6175, 4320, 2810 and 1565 were obtained. From Mw and sedimentation (S) values, the frictional coefficients were calculated for each fraction and the asymmetry ratios obtained therefrom.