washing the precipitates with water and methanol, and
drying overnight at 65 C) was followed in order to remove
potential solid impurities. Stock L/M/H chitosan solutions of
concentrations in the range 0.01–0.05 g/100 ml were prepared
by dissolving 0.1 g of each purified chitosan in 100 ml of
0.1 M acetic acid/0.2 M sodium chloride before viscosity
measurements. The analysis of each sample (at 25 0.1 C)
was repeated five times [37].