EVIDENCE OF THE PRESENCE OF LARGE AGGREGATES CONTAMINATING AMYLOSE SOLUTIONS

rapid and original macromolecular characterisation of amyloses from different origins was conducted using a combination of size exclusion chromatography (SEC) and multi-angle laser light scattering (MALLS) with 0.1 M KOH as solvent. Amylose mean-average light scattering data were too high in comparison with values obtained by intrinsic viscosity and reducing end group analysis. Dependence of polymer dimension on molecular weight (R is similar to M(v)) was determined for amyloses as well as for two series of pullulan and dextran standards. For pullulans, dextrans and Avebe amylose, the value of the characteristic exponent v was in good agreement with published results and models for linear and branched polymers in good solvents. For all other amyloses studied, two values of v were observed, with the first indicating a low dependence of the size on the mass (v almost-equal-to 0.1-0.6) and the second showing a sharp increase (v almost-equal-to 0.8-1.4) at higher molecular weight (M > 2 X 10(6) g/mol). This phenomenon can be explained by the presence of large aggregates eluted at low elution volume.