抄録
The procedures for releasing and extracting vitamin B12 from proteins in whole blood was investigated by the microbiological assay using Lactobacillus leichmannii ATCC 4797.
The treatment of the whole blood by heating with potassium cyanide was found to give constant values at each level of the vitamin, and good recoveries of the added vitamin in the assay.
The individual values of the vitamin in whole blood estimated by heating with potassium cyanide are in agreement with those obtained by using sodium metabisulfite and those by papain digestion, but not with those by digestion with the trypsin preparation available in this country.
The vitamin B12 content of healthy human whole blood was found to range from 0.10 to 0.66mγ/ml, the average value being 0.28±0.05 (U.S.A.) and 0.37±0.07mγ/ml (Japan).
