An approach to understanding the deacetylation degree of chitosan

Chitin, a polysaccharide isolated from crustaceans, is a homopolymer composed of 2-acetamide-2-deoxy-D-glucopyranose. The proportion of D-glucosamine and N-acetyl-D-glucosamine determines the classification of the biopolymer as chitin or chitosan. Chitosan a straight-chain copolymer is obtained by partial deacetylation of chitin. This study sought to compare (1)H NMR and conductometry evaluating mixtures of D-glucosamine hydrochloride (DG-HCl) and N-acetyl-D-glucosamine (NADG) because these carbohydrates are monomers of chitosan. The degree of deacetylation of three different chitosan samples was evaluated also by these two techniques. Mixtures of DG-HCl/NADG of known concentration were prepared and determined by (1)H NMR and conductimetry. The results obtained with these two techniques were in agreement with the known content of the solutions. A novel approach to understanding the deacetylation degree of chitosan and comparative studies of conductimetry and (1)H NMR employing the monomers of chitosan is described. (C) 2010 Elsevier Ltd. All rights reserved.