Vitamin methods

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Abstract
The cyanogen bromide-[rho]-aminoacetophenone method of Harris and Raymond for the estimation of nicotinic acid in urine has been further studied, and several additional improvements have been introduced, viz. (a) decolorization of the digested urine by washing with isobutanol and oxidation with KMnO4; (b) the use of a lower temp., a shorter time for the reaction of CNBr with nicotinic acid, and the addition of larger amts. of p-aminoacetophenone to the reaction mixture; and (c) the introduction of a modified blank. The normal excretion of nicotinic acid by 10 healthy subjects and the response to test doses of nicotinic acid by 4 of them has been studied. The maximum excretion of ingested nicotinic acid occurs in the first 3 hrs., the 1st hr. showing the highest output. It is emphasized that when test doses of nicotinic acid are used for assessing the body reserves of the vit., they should be administered under standardized conditions. For obtaining reliable information of the nutritional status in regard to the anti-pellagra vit., dosing with nicotinic amide is to be preferred to dosing with nicotinic acid, and estimation should then be made of the excretion of trigonelline, as well as that of other substances related to nicotinic acid.