Gel permeation chromatography. II. The nature of the separation

Gel permeation chromatography is a special type of liquid‐solid elution chromatography based on the permeation of solute molecules into a rigid gel particle. The large molecules penetrate less into the small void spaces of the gel, and they are eluted first. Ideally, the entire separation is due to the size barriers that exist within the gel. Gel columns were readily calibrated with a series of polymer samples with a narrow molecular weight distribution. Elution curves of single components were found to be symmetrical, fitting closely the normalized probability function. Peak widths divided by their elution volumes correlated well with their heights. Complete resolution of the elution curve of a low polymer was demonstrated with these correlations. Calibration curves for polystyrenes and polyglycols were brought into coincidence by plotting elution volume against chain length on a logarithmic scale. These curves were not affected by column temperature changes or by changes to other good solvents as eluants.