Toward ideal separation by size-exclusion chromatography.

In analyses of polystyrene standards by size-exclusion chromatography for polymers of molecular weight about thirty thousand and higher, the separation improved with decreasing flow-rate is in accord with Giddings observation of transversal diffusion as a factor decreasing the broadening of the band broadening function. The variance of the elution curves is larger than it corresponds to dispersity M¯w/M¯n and the shape of the elution curves depends on the experimental conditions which suggests that it reflects properties of the band broadening function. The skew and the excess kurtosis of the elution curves increase near the exclusion limit in accord with theoretical prediction for the band broadening function.