Process for the removal of endotoxins to produce medical quality chitosan and other polysaccharides

Abstract

A process of making low-endotoxin chitosan or alkali-stable polysaccharide is performed by suspending bulk chitosan fibers or flakes or alkali-stable polysaccharide to form a reaction mixture in an aqueous solution of alcohol. Ammonia is the added to the reaction mixture to raise pH of the reaction mixture to above 9.5. The reactive mixture with a pH above 9.5 is heated at a temperature of at least 130° C. for at least 20 minutes. The heated reaction mixture is cooled to less than 60° C. and then sparged with an inert gas to remove ammonia. Separating the chitosan or alkali-stable polysaccharide from the sparged reaction mixture. The chitosan fibers or polysaccharide is rinsed with an endotoxin-free aqueous liquid to form a rinsed fiber mass. The rinsed fiber mass is further rinsed with an alcohol to remove water, and dried at a temperature below 100° C. to form the low-endotoxin chitosan or alkali-stable polysaccharide.