Determination of the degree of substitution of hydroxypropyl guar gum at C-6 by Pyrolysis-Gas Chromatography spectrometry

Determination of the degree of substitution of hydroxypropyl guar gum is important as it provides information about the inhomogeneous substitution that may seriously affect the properties in various applications. In this study, the pyrolysis products of guar gum and hydroxypropyl guar gums were examined by gas chromatography and GC–MS spectrometry. Results showed that 1,2-propanediol was the product of hydroxypropyl at C-6 which splitted from the monosaccharide. Hydroxypropyl guar gums were analyzed to determine the degree of substitution at C-6, and the values were in good agreement with the values obtained by other methods. The present method is used to determine the degree of substitution at C-6 of hydroxyethyl guar gum. The present method is reliable, sensitive, and easy to operate, which provides a new way to characterize the degree of substitution at C-6 for hydroxypropyl and hydroxyethyl guar gum.