Observation of Absence of Mechanical Degradation of High Molecular Weight Polystyrenes During Elution Through a Column in Size Exclusion Chromatography

Abstract

Size exclusion chromatography of several polystyrene (PS) standards of a narrow molecular weight (MW) distribution was performed with an on-line light scattering detector (MALLS) using Shodex SEC column KF 806L packed with PS gel packings. Tetrahydrofuran was used as the mobile phase and the flow rate was 1.0 mL/min. Mechanical degradation of the sample PS was not observed even the PS sample having MW four million daltons. MW averages obtained after elution were comparable to those of vendor's values. Peak width of RI (refractometer) chromatograms increased with increasing sample concentrations and polymer components composed of the chromatograms had approximately the same MW except both ends of the chromatograms. This observation is attributed to the overloading effect and the preferable sample concentration should be as low as possible. The breakthrough volume was independent on the sample concentration, although the peak retention volume increased with the sample concentration. The decrease in molecular size with increasing sample concentration was not observed and therefore, the increase in the peak retention volume with increasing sample concentration is considered to be attributed to the overloading effect, not to the decrease in the hydrodynamic volume.