Ultrahigh molar mass component detected in ethylhydroxyethyl cellulose by asymmetrical flow field-flow fractionation coupled to multiangle light scattering

Asymmetrical flow field-flow fractionation (flow FFF) was connected to mult iangle light scattering (MALS) and refractive index (RI) detectors for char acterization of the molar mass distribution and molecular radius of a cellu lose derivative, ethylhydroxyethyl cellulose (EHEC). Experimental condition s were optimized to allow study of a wide range of molar mass including eve n ultrahigh molar mass (UHM) components. The weight-average molar mass was 3.1 x 10(5) g(.)mol(-1) representing a very broad range (of molar mass) fro m 4.0 x 10(4) to 10(7) g(.)mol(-1), which corresponds to from < 20 to 200 n m rms radius. The light scattering signal showed the presence of an UHM com ponent, possibly an aggregate of extreme size, i.e., similar to 10(8) g(.)m ol(-1) with a hydrodynamic diameter of 0.35 mum. Careful choice of the pore size in in-fine filters is necessary in order to minimize ALMS detector no ise without removing the UHM component. Flow FFF-MALS-RI was demonstrated t o be uniquely suited to detect the presence of UHM components.