An international collaborative study of dextran sulfate.

A collaborative study to determine the suitability of establishing an Author's Preparation of dextran sulfate as an international standard has been carried out. It was concluded from the results that the existing Author's Preparation should not be used for this purpose. The factors governing this decision were (a) that only a small amount of the preparation is now available, and (b) that the amount of material in the ampoules is not as accurately known as is desirable for an international standard owing to the degree of hydration of the original material.The International Unit of Dextran Sulfate has been defined as the activity contained in 0.04 mg of the Author's Preparation.