Determination of degree of acetylation (DA) for chitin in deep eutectic solvents (DES)

Abstract

Degree of acetylation (DA) is an important parameter to determine the quality of chitin. Apart from the assessment on the bond structure in the chitin molecule, infrared spectroscopy is one of the methods that can be used to determine the value of DA. The DA value of chitin is an important parameter because the value indicates the purity of chitin quality. Chitin acetylation is the process of addition an acetyl substitution group (-COCH3) to a chitin chain. The addition of acetyl will improve its dispersing properties and subsequently will improve the chitin adhesion properties within hydrophobic matrix in composite materials as well. In this study, Deep Eutectic Solvent (DES) was used as a medium for chitin extraction and acetylation in one single process. DES has two components namely Hydrogen Bond Donor (HBD) and Hydrogen Bond Acceptor (HBA). Betaine and choline chloride were used as HBA whilst urea was selected to be utilized as HBD. The findings showed that the quantity of extracted chitins by the DESs were 5.4609 % and 2.0020 % respectively. The DA values for the extracted chitins are 103.1699 and 83.4821. For acetylated chitin in DES betaine - urea, the DA value was increased from 103.1699 to 118.4818. The findings showed that the high quality acetylated chitin can be produced in a single process involving extraction and acetylation process by using DES as a medium.