Qualitative investigation using a highly sensitive colorlessreagent hydroquinone, which turns to black colored quinine dur-ing the reaction with oxygen, have shown that dry chitosan beadskept in air for a long time (2–3 days) adsorb rather small amountsof oxygen. When air or oxygen passes through chitosan-deionizedwater slurry, the amount of adsorbed oxygen remarkably increases.It is especially high in the case of anodic treatment of chitosan.However, due to the sensitivity of hydroquinone to oxygen and thecomplexity of the required installations for the precise investiga-tions, the amounts of adsorbed oxygen onto the chitosan surface inthe case of forced introduction of oxygen were not determined.