Determination of Nicotinic acid
The chemical methods of assay are based on colour reactions of pyridine. Nicotinic acid and nicotinamide are converted by cyanogen bromide into a derivative of the glutacone aldehyde, which is condensed with aromatic amines to form polymethine dyes (yellow colouring reactions).
The microbiological assay involves the titrimetric determination of lactic acid produced by Lactobacillus arabinosus ATCC 8014.