1 AIT Asian Institute of Technology

Study of possible new methods to determine the degree of deacetylation of chitosan

AuthorShrestha, Anjala
Call NumberAIT Thesis no. BP-98-15
Subject(s)Chitosan

NoteThesis report submitted in partial fulfillment of the requirements for the degree of Master of Science in Bioprocess Technology, School of Environment, Resources and Development
PublisherAsian Institute of Technology
AbstractNew methods are proposed for determining the degree of deacetylation of chitosan. Metal adsorption, ninhydrin and Ehrlich's reagent were used to quantify -NH2 content in chitin and chitosan. In solid state, chitin shows less adsorption capacity as compared to chitosan There is a decrease in Cu(Il) adsorption as % DD increases. Spectrometric determination of metal ions is not enough sensitive to distinguish among the samples. So the metal adsorption method has not enough accuracy to determine the % DD of chitosan. Direct absorbance of dilu te solution of chitosan in 0.1 M acetic acid at a concentration of 0.01 g of chitosan per litre shows maximum absorbance at 190 nm. At this wavelength, chitosan of different % DD (60%, 75%, 86% and 95%) gives a straight line having a negative slope which is due to absorbance of N-acetylglucosamine moieties. This technique can be used to detect % DD by comparing with the standard curve of% DD at 190 nm. Ehrlich's reagent can directly react with a chitosan dissolve in 0. 1 M acetic acid. The final chromogen has OD at 410 nm and it has also linear relationship between concentration and absorbance. A good straight line is obtained with % DD of chitosans and their absorbance at 5 mg/ml concentration. By estimating the amount of glucosamine in the sample, % DD is calculated. This method estimates lower value of -NH2 than the reference method, i. e. Acid hydrolysis-HPLC method. There is no significant difference between the water-binding capacity of chitin and chitosan samples tested in a saturated environment of water at room temperature (22-25°C). Equlibrium is reached after 24 hours of putting in saturated environment of water. In dry ambiance, dehydration of chitin and chitosan is very fast in first 24 hours.
Year1998
TypeThesis
SchoolSchool of Environment, Resources, and Development (SERD)
DepartmentDepartment of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB))
Academic Program/FoSBioprocess Technology (BP)
Chairperson(s)Didier, Montet;
Examination Committee(s)Stevens, Willem F. ;Suwalee Chandrkrachang ;Rakshit, Sudip Kumar ;Pakorn Nuchnoi ;
Scholarship Donor(s)H.M.King's Scholarship, Thailand ;
DegreeThesis (M.Sc.) - Asian Institute of Technology, 1998


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