Determination of the degree of N‐deacetylation in chitin and chitosan as well as their monomer sugar ratios by near infrared spectroscopy

Chitin and its derivative chitosan are rapidly becoming of commercial interest in the biomedical, wastewater treatment, and fiber industries. One of the most important properties of these copolymers is the degree of N ‐acetylation. Presently there is no rapid accurate method to determine this value. We propose near infrared spectroscopy for such a method. Using a primary method such as hydrobromic acid titration or 1 H‐NMR, standards can be established. Once a model calibration equation has been developed, unknown samples can be analyzed by near infrared spectroscopy in less than 5 min. This is demonstrated by examining representative structural monomers of chitosan, N ‐acetyl‐D‐glucosamine and D‐glucosamine hydrochloride, as model compounds as well as actual chitin and chitosan samples.