A robust and universal NMR method for the compositional analysis of polysaccharides

Abstract

A method is presented for the detailed and accurate quantitative determination of the monomeric composition of polysaccharides. The method is a modification of the well-known Saeman hydrolysis in combination with 600 MHz (1)H NMR quantification. Experimental conditions for this two-step hydrolysis have been optimized for cellulose and hemicelluloses, and the method has been applied to several other polysaccharides as well. It is shown that even very resistant polysaccharides are hydrolyzed completely, while at the same time degradation of monosaccharides is kept at a minimum. The degradation of monosacharides is corrected for by subjecting a standard mixture represented in the polymer to the same conditions. This correction results in a very accurate and reproducible method with relative deviations down to 1%. It is shown that the duration of hydrolysis and the concentration of sulfuric acid in the second hydrolysis step are the most important factors to determine the reliability of the results.