The Use of Titration Technique and FTIR Bands to Determine the Deacetylation Degree of Chitosan Samples

Abstract

The use of titration technique is proposed as an alternative method to determine the degree of deacetyletion (DD) in chitin/chitosan samples, based in both volumes taken before and after titration, and the unit mass of chitosan samples. Chitosan was partially deacetylated to different levels and obtained samples were characterized using Fourier Transform Infrared Spectroscopy (FTIR) to observe the change in band formation. Moisture uptake (%) were also calculated to observe the physical changes in the polysaccharide structure. Crystalline structures were observed and analyzed to see the change in the crystal structure of the anhydrous form of chitosan after deacetylation. It is noticed that the acetyl group can contribute to the formation of hydrogen bonds that can stabilize the crystalline structure. In addition, it is found that the samples with higher acetylation degree presents a higher water absorption percentage. This study describes the role of the functional group, acetyl groups, in crystalline chitin. Such information could provide preliminary understanding of chitosan samples in different degree of deacetylation which similar functional groups are encountered.