Preparation of Radiocyanocobalamin-60Co

When cobalt-60 was added in the fermentation medium of Streptomyces griseus, cyanocobalamin (vitamin B₁₂) labeled with Co⁶⁰ was obtained by biosynthesis. The extraction and purification method of radiocyanocobalamin from the fermentation broth was established in consideration of improving radiochemical purity and protection against radiation. In this procedure radiocyanocobalamin was purifled using the techniques of chromatography with alumina and treatment with ion exchange resins. It was evidenced by paper chromatography that the radioactive impurities were thoroughly removed by this purification procedure. Also, the method of quality test of radiocyanocobalamin solution was established. Finally, about 1 mc of Co⁶⁰ with specific activity of 14 mc/mg was added in the fermentation medium and radiocyanocobalamin- Co⁶⁰ was prepared. In the purified solution, radiocyanocobalamin with specific activity of 0.5 mc/mg was contained with concentration of 1.1 mic ons/ml. This solution was sufficientiy pure for practical