Abstract
The cup-plate assay method for pantothenic acid with Lactobacillus arabinosus as test organism, in the case of a pure solution of the vitamin was satisfactory enough in the specificity, precision and response range, though it was relatively insensitive. However, when the assay solutions for total pantothenic acid from several animal and vegetable samples obtained both by an enzymatic treatment and by a boiling water extraction were used, it was almost unable to determine the net content of the vitamin, because of a presence in these samples of certain factors affecting the growth zone responses of the test organism. Thus, so far as the present preparations of pantothenic acid from natural products are employed, the valid and reliable assay of the vitamin by the plate technique cannot be expected.
