Compositional analysis of polysaccharides

Angela Dawn Broeker, Purdue University

Abstract

A method was developed that overcomes some of the deficiencies in current methods that prevent determination of the exact monosaccharide composition of polysaccharides other than those that have regular repeating unit structures and, therefore, whole number ratios of constituent sugars. These deficiencies are differences in rates of release and rates of destruction of different sugars during acid-catalyzed hydrolysis and different detector response factors for each sugar. The developed method (1) provides rapid and complete depolymerization of the polysaccharide without destruction of constituent monosaccharides; (2) converts each monosaccharide into a major and minor derivative; (3) converts sugar units into derivatives that can be separated by HPLC and detected with a UV flow detector; (4) gives molar amounts of each sugar from UV detection after application of a constant response factor; and (5) can be used to determine the ratio of monosaccharide units in a polysaccharide. The method involves use of liquid anhydrous hydrogen fluoride at room temperature as a polysaccharide solvent, to provide solvolysis of glycosidic linkages, and as a reaction medium for specific coupling of 2,6-dimethylphenol to each released monosaccharide. The coupling reaction produces derivatives detectable with a UV detector. HPLC separation utilized a gradient solvent system of water and acetonitrile and a C18 reversed phase column. Peak areas were compared using a response factor because of differences in molar absorptivity among monosaccharides. Reliability of the method was confirmed by analyzing polysaccharides of known composition.

Degree

Ph.D.

Advisors

BeMiller, Purdue University.

Subject Area

Food science|Organic chemistry|Analytical chemistry

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