Macromolecular characterisation of three barley beta-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 labo ratories with varying columns, solvent conditions and detector systems (low - and multi-angle light scattering and viscometry). Static (batch) measurem ents by capillary viscometry and laser light scattering were included. Fair ly consistent results were obtained for the weight average molecular weight s (M-w), radii of gyration (R-G) and intrinsic viscosities [eta], demonstra ting that the beta -glucans may serve as useful standards or reference mate rials 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 inco nsistencies 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 pr ocessing parameters, especially refractive index increments (dn/dc), due to ambiguities in the literature or to differing experimental values. The nee d for consistent parameters and processing methods is clearly demonstrated. (C) 2001 Elsevier Science Ltd. All rights reserved.