Chitosan (CH) was kindly provided by the Norwegian Chitosan (Norway). Its deacetylation degree (DDA), determined NMR spectroscopy (in D20 containing 1% of CD3COOD) using a RX-300 Bruker instrument was found to be 90%. its viscosity average molecular weight, obtained at 25*C from a 0.3 M CH3CO2H/0.2 M CH3CO2Na solution using the published Mark- Houwink constants , was 90,000.