Comparison between Size Exclusion Chromatography and Micro-Batch Analyses of Corn Starches in DMSO using Light Scattering Detector

The molecular structure of corn starches different in amylose content (waxy, normal, and high-amylose) was analyzed in 90% dimethyl sulfoxide (DMSO) solution by refractive index (RI) and multi-angle laser light scattering (MALLS) detectors. The starch sample solutions were measured either by medium-pressure size exclusion chromatography (MPSEC) or by the micro-batch mode. For waxy corn starch, the average molar mass (Mw) and radius of gyration (Rg) values were similar in both methods. However, for normal and high-amylose corn starches, Mw measured by the micro-batch mode was 2–4 times greater than that by the chromatographic method, although Rg values obtained from both methods were not very different. The Mw difference was the greater the higher the amylose content of starch.