The Mark–Houwink equation was used to determine
the molecular weight of the different chitosans using the
measured viscosity numbers. The tests were carried out
in an Ubbelohde-type capillary viscometer (Visco System
AVS 350, Schott-Gerate, Germany). Purification of 1% (w/v)
chitosan based solutions in 0.8% (v/v) acetic acid (by
precipitating with a sodium hydroxide solution, filtering,