Characterization of silver-binding chitosan by thermal analysis and electron impact mass spectrometry

Chitosan becomes thermally less stable as a result of complex formation with silver. A comparison of the thermal curves of a sample containing 210 mg silver g⁻¹ chitosan with those of chitosan showed that not all the polymer is engaged in complex formation and only about 52% of the silver present is actually complexed, the remainder being retained by sorption. The evaporation curves obtained in mass spectrometry exhibited a maximum for chitosan and two maxima for silver-containing chitosan. A comparison of the peak ratios 80:60, 67:60 and 80:42 for the components of each maximum corroborates the fact that silver-containing chitosan can be considered as a mixture of complexed and uncomplexed polymer.