On-line Size Exclusion Chromatography and Multiangle Laser Light Scattering of High-Molecular-Weight Rigid Polysaccharides

High-molecular-weight ‚rigid‘ polysaccharides from bacterial origin, namely xanthan and schizophyllan, were studied in 0.1M LiNO3 solutions by applying a size exclusion chromatographic system in combination with a multiangle laser light scattering detector and a refractive index detector. Both the light scattering and the elution behavior show peculiarities indicating the presence of particles of large size (microgels and/or aggregates). This complicates the interpretation of experimental data and explains why the radius of gyration scales with the molecular weight with a slope much smaller than that expected for molecularly dispersed molecules. Partial removing of such contamlnants as a result of sonifying and/or ultrafiltration treatments yields polysaccharide solutions of improved quality.