British standard for human serum vitamin B12

Seven laboratories took part in a collaborative study of an ampouled preparation of normal serum labelled 81/563. Each laboratory calibrated the preparation in terms of pure cyanocobalamin by use of Euglena assay. The inclusion of pernicious anaemia serum in the study and additional tests for safety and stability indicated that 81/563 would be a suitable standard for diagnostic testing. In 1985 the National Biological Standards Board established the preparation as the British Standard for Human Serum Vitamin B12 and, with the agreement of participants in the study, assigned it a potency of 320 picograms per ampoule.