UV spectroscopy: A novel method for determination of degree of substitution of phthaloyl group as amine protector in chitosan

The purpose of this study is to introduce and develop a new experimental method based on UV spectroscopy for measuring the degree of substitution (DS) of phthaloyl group used for protecting amine group in chitosan, a biopolymer derived from chitin that has a wide variety of applications including drug delivery in pharmaceutical products. N-phthaloylated chitosan was synthesized and the UV absorption measurements were performed on its solutions with different DS with concentrations of 6.25, 12.5, 25, 50, and 100 μg/mL in DMSO at 295 nm. The accuracy of the method was checked with H-NMR and there was consistency between the results obtained by two methods. This suggests that the UV spectroscopy can be a potential method for the characterization of the polymer and can replace the difficult methods of analysis used for the chemical structure.