In this study four chitosan samples were used, of similar nominal viscosity (ca.
1000 mPas at 1% in 1% acetic acid, 20 °C) but different degrees of deacetylation. Samples
have been manufactured and donated by Heppe Medical Chitosan GmbH. Chitosans were
of high purity (Chitoscience® product line) and had individual certificates of analysis. These
samples are denoted here as S1, S2, S3 and S4. DD values of these samples determined by 1H NMR technique were taken as the reference values for all other determination methods.
Chitosan samples were dried at 40 °C in vacuum until constant mass. All reagents were of
analytical purity.