Separations of polysaccharides related to starch by electrokinetic ultrafiltration in collodion membranes

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Abstract
In order to circumvent difficulties commonly encountered in chromatographic separation of members of polymeric series, particularly difficulties due to molecular-sieve effects, a procedure was devised for conducting chromato-graphy inside a strip of collodion ultrafiltration membrane. Flow of lipid in the membrane is produced electrokinetically. The procedure was evaluated using a series of linear dextrin preparations of known average degree of polymerization (DP). Information was gained as to the range of DP represented in the various preparations. The separations effected can be explained in terms of normal absorption of the polysaccharides on the inner surfaces of the membranes. However, ultrafiltration effects prevent molecules greater than a certain size from entering the membrane. Comparisons of adsorption during free diffusion, mechanical ultrafiltration and electrokinetic ultrafiltration suggest the adsorption equilibria at the surfaces may be modified under electrokinetic flow conditions. Results are reported on velocity of electro-kinetic flow in relation to the pore size of the membranes. Several polysaccharide preparations related to or derived from starch have been studied by the new procedure, and estimates of DP range have been made for the cases of linear polymers. The new procedure is discussed in relation to previous work on the chromatography of polysaccharides.