CHARACTERIZATION BY SIZE-EXCLUSION CHROMATOGRAPHY WITH REFRACTIVE-INDEX AND VISCOMETRY - CELLULOSE, STARCH, AND PLANT-CELL WALL POLYMERS

High molecular weight natural polymers are difficult to characterize because isolation, extraction, and dissolution often degrade the polymers and no good molecular weight standards exist. In our laboratory, cellulose, starch, and plant cell wall materials have been directly dissolved in the nondegrading solvent dimethylacetamide-lithium chloride (DMAC-LiCl) without prior isolation or extraction. Size-exclusion chromatography with viscometry and refractive index detectors was used with DMAC-LiCl as the mobile phase. The universal calibration concept was applied to obtain molecular weight distributions (MWDs). Applications include cotton fiber, con and wheat starch flours, and avocado cell walls. Relationships were determined between the respective MWDs and cotton fiber variety, inheritance, textile processing, and strength; starch extrusion conditions; and avocado ripening stage.