This commercial sample was purified

This commercial sample was purified by reprecipitation from apreviously filtered 1% aqueous CH3CO2H solution into an excess ofa 10% NaOH aqueous solution. The ensuing precipitate was exten-sively washed with distilled water until a neutral pH. The solutionsof chitosan and its fluorescent derivative in aqueous CH3CO2H usedin this study were prepared from this purified sample by stirringfor 24 h at room temperature, filtering and degassing. They werethereafter stored in the dark.