3.3. Effects of acid concentration and temperature on glucosamine decomposition
Since glucosamine is known to be deaminated by acid hydrolysis (Shabrukova et al., 2002), it is necessary to minimize the decompositionto achieve an accurate result for chitosan quantitation. To determine the degree of decomposition, glucosamine samples were weighed into digestion tubes and treated with the selected hydrolysis condition (105 ◦C, 10 M HCl). At the end of each hour interval, a sample was taken and analyzed for glucosamine. The results were recorded and are shown in Fig. 4. The degradation of glucosamine fits a first-order decomposition model. After 6 h of hydrolysis, we observed approximately a 20% loss of glucosamine. However, the decomposition kinetics during the chitosan hydrolysis process are complicated by the processes of chitosan depolymerization and deacetylation, and glucosamine generation. The glucosamine decomposition during chitosan hydrolysis does not appear to have a significant impact on chitosan recovery. The glucosamine content of the chitosan plain material is 93.6% (w/w, average results from two analysts, Table 1) which is experimentally close to the nominal chitosan content of the plain material (95%). The recovery of glucosamine from the formulation was greater than 99%, demonstrating that the decomposition of glucosamine during chitosan hydrolysis at the specified conditions has minimal impact on assay accuracy.