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Hydrodynamic Chromatography of Waxy Maize Starch

¹National Center for Agricultural Utilization Research, Biomaterials Processing Research and Bioactive Agents Research, respectively, ARS, USDA, MWA, 1815 N. University, Peoria, IL 61604. Mention of trademark or proprietary products does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable. ²Corresponding author. Phone: 309/685-4011. Fax: 309/681-6686.

A hydrodynamic column packed with solid beads chemically bonded with N-methyl-D-glucamine residues was used with 90% dimethylsulfoxide (DMSO)-H₂O mobile phase as part of a chromatographic system to characterize jet-cooked waxy maize starch. Software calculations based on signals from refractive index and dual-angle light-scattering detectors indicated the column could fractionate molecular weights up to ≈5 × 10⁸. Calculated molecular weight values for the highest molecular weight sample was greatest at the lowest flow rate of 0.1 mL/min. Values of molecular weights and radii of gyration determined by the in-line dual-angle light-scattering detector were significantly less than those determined with an off-line multiangle light-scattering detector that examined samples that had not traveled through the hydrodynamic column. This work has demonstrated the feasibility of using a hydrodynamic column to characterize waxy maize amylopectins. However, considerations of sample shear sensitivity and questions of in-line light scattering detection show that further efforts are required to develop and optimize a chromatographic system to characterize very high molecular weight amylopectins.