International Reference Preparation for vitamin B12.

The International Reference Preparation for Vitamin B(12) was prepared in tablet form from a mixture of anhydrous cyanocobalamin and sodium chloride. In an international collaborative study, in which eleven laboratories participated, this preparation was examined qualitatively and quantitatively by spectrophotometric and microbiological methods. It was concluded that the International Reference Preparation is substantially pure and has a potency of 9.3 mug of cyanocobalamin per 20 mg of tablet.