Applying different infrared spectrophotometry methods for determining
No Thumbnail Available
Date
2022-10
Authors
Hromiš, Nevena
Popović, Senka
Šuput, Danijela
Ugarković, Jovana
Čabarkapa, Ivana 
Journal Title
Journal ISSN
Volume Title
Publisher
University of Novi Sad, Faculty of Technology Novi Sad
Abstract
Chitin, the most abundant biopolymer after cellulose, is a linear, highly crystalline
polysaccharide, built from acetylglucosamine monomer units connected by β-1,4 glucosidic
bonds. High degree of acetylation (DA) and the crystallinity of chitin molecules make it
insoluble in common commercial solvents. Chitosan is the name for chitin substitutes with a
low degree of acetylation. The degree of deacetylation in chitin usually ranges from 5% to 15%,
and in chitosan from 70% to 95%. This contributes to the solubility of chitosan in aqueous
solutions of acids and enables the use of chitosan and its bioactivity. When chitosan biopolymer
film properties are considered, DA is an important input, due to the proven influence of DA on
chitosan film´s mechanical, physico-chemical and bioactive properties. Developed methods for
chitosan DA determination are based on different approaches: infrared spectroscopy, UVspectrophotometry, nuclear magnetic resonance, colloidal titration, and potentiometric titration.
Various procedures using infrared spectroscopy technique have been developed to determine
DA of chitosan. In this article, these methods were tested for application on chitosan isolated
from blue crab shell (Callinectes sapidus). Two different approaches were assessed: 1)
determination of the absorption ratio of a probe band and of a reference band and estimation of
DA of unknown samples by comparison with samples with known DA and 2) evaluation of
several proposed absolute methods that are used in the literature for the DA determination.
Results showed that applied absolute methods gave results that varied between the methods
applied, but were consistent among different samples within the framework of a particular
method. Use of different probes and reference bands for calculation of ratios that would be
compared to the reference samples of a known DA was more appropriate method. Selected
ratios were A1655/A3450 and A1320/A1420.
IR techniques for chitosan DA determination without reference to samples of known DA or
calibration curve could be used for qualitative evaluation of DA, while quantitative
determination should include mentioned references. Use of absolute methods for determination
of DA by IR spectroscopy was shown not to be appropriate in this work
Description
Keywords
Chitosan,, Acetylation, Degree, Infrared spectrophotometry
Citation
Hromiš, N.; Popović, S.; Šuput, D.; Ugarković, J.; Čabarkapa, I. Applying different infrared spectrophotometry methods for determining. 2nd International Conference on Advanced Production and Processing, 20th-22nd October 2022, 55.