Pore size distribution analysis of gel substances by size exclusion chromatography

A “mixed solute exclusion” method for teh porous structure analysis of gel substances has been developed. A mixed solution of polymer and oligomers covering a sufficiently wide molecular weight range is brought into contract with a gel sample and the resulting differential dilution of the solute fractions is determined as a function of the molecular size by means of gel permeation chromatography (GPC). This method and two other versions of the solute exclusion technique, the single-point method (equilibrium partitioing) and the column method (inverse GPC), were applied to a cross-linked dextran gel (Sephadex G-100) using dextran and/or poly(ethylene oxide) fractions as the probe polymer. The results of the three methods were consistent with each other and demostrated the efficacy of the mixed solute exclusion method for the rapid analysis of gel structure. An important limitation, however, is the resolution of solute exclusion methods in general, as shown by examining the assumptions in interpreting a solute exclusion curve as a pore size distribution curve.