Solid state NMR for determination of degree of acetylation of chitin and chitosan.

The degree of acetylation (DA) of various samples has been evaluated by 1H liquid-state NMR and 13C and 15N CP-MAS solid-state NMR over the whole range of DA. A good agreement has been found for all the experiments. The 13C and 15N CP-MAS experiments have permitted the evaluation of the chitin DA and content in the structural polysaccharides in a fungus named Aspergillus niger. The fungus structural carbohydrates mainly consist in pure chitin associated with glucans. Comparison of the 13C CP-MAS spectra with standard (1-->3)-beta-D-glucans strongly suggests that chitin and glucans are linked via covalent bonds.