43
5. Viscosity
The determination of viscosity was made by rotary viscometer at 20C° equipped with a
spindle in the rotational speed and 20 revolutions per min.
6. Water insoluble substance
➢ Add 2 gr of chitosan hydrochloride to 400 ml of water, stir until the salt is completely
dissolved.
➢ Pour the solution into a 2-litter precipitation vessel then add 200 ml of water.
➢ Boil gently for 2h, covering the vase to precipitate during the operation.
➢ Filter through sintered glass filter 40, wash the residue with water and dry to constant
mass in an oven at 100-105C°.
7. Chlorides : 10-20%
Insert 0.200 g of chitosan hydrochloride into a 250 ml borosilicate flask with reflux
refrigerant. Add 40 ml of a mixture of 1 volume of nitric acid R and 2 volumes of water R.
Boil gently at reflux for 5 min. Cool and add 25 ml water R through the refrigerant. Add 16.0
ml of nitrate silver 0.1M and then shake vigorously. Titrate by the 0.1 M ammonium
thiocyanate, in the presence of 1 ml Ferric sulphate and ammonium R2 solution, stirring
vigorously approaching the turn. Perform a titration blank.
1 ml of silver nitrate 0,1 M corresponds to 3,55 mg of Cl.
8. Loss on drying : 10%
Determined in an oven at 105° on 1g of chitosan hydrochloride.