Spectroscopic characterization and preparation of low molecular, water-soluble chitosan with free-amine group by novel method

Abstract

Low molecular, water-soluble chitosan (LMWSC) with a free amine group was prepared by the novel salts-removal method described in this study. A weight-average molecular weight and degree of deacetylation (DDA) of LMWSC were determined by viscometry and Kina titration, resulting in 18,579 Da and 93% DDA, respectively. In the Fourier transform infrared spectroscopic, 1H NMR and 13NMR spectra the absorption and band by the carboxyl group derived from lactic acid and the impurities formed in the enzymatic process disappeared or were significantly lower than that of the control chitosan. Also, from the 1H NMR and 13C NMR spectra the empirical value for the area ratio of the proton and carbon corresponds nearly to its theoretical values. The matrix-assisted laser desorption/ionization time-of-flight mass spectrum identified the difference in the two adjacent peaks as 161.