2.2.1. 1H NMR Spectroscopy [6]
Dilute solutions (5–7 mg cm-3) of chitosan samples in a deuterated aqueous acid
DCl/D2O, at about pH 4 were prepared. 0.05 g - 0.07 g chitosan was weighted in plastic
tube. Next, 6 cm3 D2O and 1 cm3 deuterium chloride was added to every sample to obtain
a solution. D2O and DCl were further added to the final volume of 10 cm3 and pH of ca.
4. The samples were twice freeze-dried using D2O (99.9%) to exchange labile protons by
deuterium atoms. Measurements were made for three samples of every kind of chitosan.
Spectra between 0 - 6 ppm were recorded using a NMR spectrometer Bruker Avance II (700
MHz) at the temperature 27 °C and 60 °C. Integrals under characteristic signal are used to
calculation degree of deacetylation.