Macromolecular characterisation of three barley β-glucan standards by size-exclusion chromatography combined with light scattering and viscometry:: an inter-laboratory study

Six (1 --> 3)(1 --> 4)-beta -D-glucan standards (A-F) isolated from barley were analysed by size-exclusion chromatography (SEC) in five different laboratories with varying columns, solvent conditions and detector systems (low- and multi-angle light scattering and viscometry). Static (batch) measurements by capillary viscometry and laser light scattering were included. Fairly consistent results were obtained for the weight average molecular weights (M-w), radii of gyration (R-G) and intrinsic viscosities [eta], demonstrating that the beta -glucans may serve as useful standards or reference materials in the study of cereal beta -glucans. Average values for M-w were: A,E: 114,000 (+/-11%); B,C: 374,000 (+/-9%), D,F: 228,000 (+/-13%). Some inconsistencies regarding the polydispersity (M-w/M-n) could be ascribed to the influence of peak broadening in certain column/solvent systems. The study further demonstrated that individual researchers tended to use different processing parameters, especially refractive index increments (dn/dc), due to ambiguities in the literature or to differing experimental values. The need for consistent parameters and processing methods is clearly demonstrated. (C) 2001 Elsevier Science Ltd. All rights reserved.