Determination of N-acetylation degree in chitosan using Raman spectroscopy

• Spectroscopic determination of deacylation degree of chitosan has been proposed.
• Equations for determination of degree of deacetylation have been derived.
• The discussions have been based on DFT quantum chemical calculations of chitosan.

Application of Raman spectroscopy in determination of the acetylation degree (DA) of chitosan has been developed. The spectra of several chitosan samples characterized by different DD (degree of deacetylation) in the range 50–100% have been measured. The integral intensities of the bands assigned to the vibrations of amine group and glucosidic ring were used to calculate the DA from the intensity ratio. The assignment of the bands to the respective normal modes of chitosan was based on the DFT quantum chemical calculations. This method has a number of advantages over other techniques. It is fast and does not require purification of the sample nor require dissolution of the chitosan in any solvent.

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