Measurement of the degree of deacetylation in chitosan films by FTIR, 1H NMR and UV spectrophotometry

Abstract

The chitosan films were prepared from shrimp, squid, and crab to corroborate that regardless of the source of the chitosan, it was possible to measure the degree of deacetylation. In this work, the degree of deacetylation of chitosan was evaluated via UV, FTIR and 1H NMR spectrophotometry methodologies. Values in a range of 74 to 99% degree of deacetylation (DD) were obtained and varied depending on the method used and the source of chitosan. The spectrophotometric method is one of the most commonly used for this determination; however, it has the limitation that D-glucosamine and N-acetylglucosamine share similar wavelengths. All three methods were simple and provided rapid analysis; however, NMR, in particular, was expensive due to its equipment specifications. For this reason, its important to select the simplest method than can be routinely used.•The simplest used technique to determine the degree of deacetylation is infrared spectroscopy.•The degree of acetylation of chitosan is related to its physicochemical properties; its determination is an important parameter due to its association with chitosan applications in different industrial areas.•The 1H NMR method is very precise and requires expensive equipment and trained personal. Thus, it cannot be used routinely to determine the degree of deacetylation.