Cup Assay with Vitamin B 12 as a Standard

Abstract
Factors crucial for assay by the cup method apply equally well to the detn. of growth-promoting and antibiotic factors. The technic allows a rigid control of influential factors, hence gives great precision. The constituents and preparation of the media and assay organism are described and details of the technic are given. Standard deviations found for cup assay were [plus or minus] 10% as compared with t 21% for the titrimetric assay with the same organism and similar replications.
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