Investigations into the Euglena method for the assay of the vitamin B12 in serum

摘要

Details are given of a modified Euglena method for the assay of B12 in serum. Serum in very small quantities is usually inhibitory to the growth of the Euglena. In general, this inhibition is most marked when the organism is growing prolifically. For estimating serum B12 values, a standard curve is used from B12 standards containing 0·01 ml. of serum of low B12 content, so that growth in test serum solutions is compared with growth in serum-containing standards. The recovery of B12 added to serum, incomplete when estimated from aqueous standards, is now complete and the variation in results from batch to batch is markedly reduced.