[The Cyanocobalamin Reference Standard (Control 931) of the National Institute of Health Sciences].

Raw cyanocobalamin material was tested for preparation of the "Cyanocobalamin Reference Standard (Control 931)". Analytical data obtained were as follows: loss on drying, 4.2%; infrared spectrum, the same as that of the JP Cyanocobalamin Reference Standard (Control 901); thin-layer chromatography, four impurities were detected; high-performance liquid chromatography (HPLC), seven to eight kinds of impurities were detected, but the total amount of impurities was only 1.0 +/- 0.52% (n = 5); assay results, 100.6% by spectrophotometry in the JP XII and 99.7% by HPLC. Based on the above findings, the raw material was authorized as the JP Cyanocobalamin Reference Standard (Control 931).