A methodology for the selection of a routine purity test for insoluble beta(1-->3)glucan

Beta(1-->3)glucan isolated from the cell wall of Saccharomyces cerevisiae is a biological response modifier (BRM) stimulating resistance against bacterial, viral, fungal and protozoal diseases. This polysaccharide has a high molecular weight, which makes it very difficult to achieve a purity test. A comparative study of different analytical procedures for beta(1-->3)glucan from S. cerevisiae was conducted in order to establish a reliable routine analytical methodology for quality control of this active ingredient in pharmaceutical products. With this aim, different combinations of the analytical procedure steps were tested, including three alternatives for the acid hydrolysis step, three for neutralization, two for gas-liquid chromatographic derivatization and two internal standards. The glucose yield, precision, time consumption and reagent cost per sample were determined for 10 sample replicates. All gas chromatographic determinations were conducted using packed GLC columns and an FID detector. The selected analytical method showed 83.61 +/- 3.48% glucose yield, the shortest relative time consumption (54.2%) and the lowest cost of reagents (7.4%) and consisted of a combination of 72% sulfuric acid hydrolysis, 25% ammonium hydroxide neutralization and alditol acetate derivatization using xylose as internal standard.