The properties of insoluble particles which are formed on the storage of 10% Dextran in vials containing injectable solution were investigated. No evident difference between the insoluble particles and Dextran 40 was detected in the physico-chemical properties such as mp, specific rotation, intrinsic viscosity, and sedimentation constant. Furthermore, the insoluble particles were found to consist mainly of α-1, 6-glucan by measurement of nuclear magnetic resonance and infrared of the substance and after acid hydrolysis. The insoluble particles were found to be soluble in water at 90° and in solutions of 8M urea, 3M guanidine hydrochloride, 2.5M NaOH, and dimethyl sulfoxide. The solution of Dextran 40 of more than 30% in concentration tended to become turbid on standing, followed by gelation. From these facts it was speculated that the formation of particles in the vial might be that Dextran 40 adhered was concentrated on the surface of a rubber stopper and formed an intermolecular hydrogen bonding with one another.
