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

Abstract Six (1→3)(1→4)-β- 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 [ η ], demonstrating that the β-glucans may serve as useful standards or reference materials in the study of cereal β-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 (d n /d c ), due to ambiguities in the literature or to differing experimental values. The need for consistent parameters and processing methods is clearly demonstrated.