Hydrodynamic chromatography separation of polymer solutions

Abstract

Hydrodynamic chromatography can supply information on the molecular weight and the molecular weight distribution of a broad range of ultra-high molecular weight polymers for which other, more conventional, techniques have failed. Separation based on the molecular size results from flow through the interstitial regions of a packed bed of impermeable spheres. The ratio of the elution volume of small marker species to that of the sample defines a measure of separation called the retention factor, R$_f$ Molecular theories for three basic polymer models are developed to calculate the R$_f$ and we compared this theoretical value of R$_f$ with other experimental data, and our experimental data for Xanthan. R$_f$ increases as the size of polymer increases. A decrease in R$_f$ is noted as Xanthan is degraded by sonication. The chromatograms of the sonicated samples show a progression of polymer degradation which is consistent with theoretical predictions of a central chain scission model. The experiments demonstrate that HDC is capable of distinguishing a broad range of macromolecules based on size.