Improved method for measuring vitamin B12 in serum using intrinsic factor 57CoB12 and coated charcoal

摘要

An improved and simplified method is described for the measurement of vitamin B12 in serum using intrinsic factor, ⁵⁷CoB12, and coated charcoal. The extraction of serum in the presence of cyanide and the incorporation of B12-deficient serum into the intrinsic factor control has increased the accuracy of the method for both sera and crystalline B12 solutions. There are interesting differences between the results obtained for some sera by the isotope and L. leichmannii methods and the reasons for these differences are discussed.