High‐resolution gel‐permeation chromatography

Abstract The resolution attainable in gel‐permeation chromatography (GPC) was investigated by using columns packed with polystyrene gel particles of about 5 μ diameter and mixtures of two monodisperse poly‐α‐methylstyrene samples studied previously. The resolution of GPC was found comparable to that of the sedimentation velocity method and slightly better than that of precipitation chromatography. Standard polystyrene samples obtained from Pressure Chemical Co. also were measured with the same columns. It was found that weight‐average to number‐average molecular weight ratios (M̄w/M̄n) of these samples with molecular weight in the range 97,000–411,000 are smaller than 1.006. For samples with molecular weight of 10,000–51,000 and 498,000–860,000, M̄w/M̄n is larger than 1.006, and the width of molecular weight distributions of these samples differed. In particular, molecular weight distributions of samples with molecular weights 19,800 and 51,000 were shown to be bimodal. It is therefore concluded that GPC is useful for samples of very narrow molecular weight distribution if high‐resolution columns are used.