Multifarious Techniques for Resolving Chitosan’s Degree of Deacetylation (DD)

Chitosan is a copolymer created from chitin by partial deacetylation. It is a versatile biopolymer due to its many areas of applications. The usefulness of chitosan is hinged on its quality parameters, such as degree of deacetylation (DD), molecular weight, viscosity, turbidity, and other parameters. Still, the DD is the most valuable of them. There are several different techniques for chitosan DD determination, which have been classified into spectroscopic and non-spectroscopic techniques. 1H-NMR is the most precise, accurate, specific, and reliable technique for DD determination, but its expensiveness limits its application in routine analysis. The IR technique is the fastest and simplest for chitosan DD value evaluation. Meanwhile, the concentration of chitosan sample sufficient to elicit absorbance in the IR region ranges from 1.0-10.0 mg/mL-1, which is far smaller than the concentration or amount of chitosan required for DD determination by titrimetric techniques. Titrimetric techniques require the largest sample, while UV spectrophotometry requires the least chitosan sample for DD determination. Although the elemental analysis technique is not as common as IR and the titrimetric techniques, it is simple, cost-effective, and gives reliable DD data. It does not require the use of standard solutions and calibration curve(s) as applicable to the UV-technique. It is a tedious task to select a suitable technique for DD determination. It is, therefore, desirable to consider the time of measurement, precision, and accuracy of measurement results, as well as the cost-effectiveness when choosing a technique to use for DD determination.