Unsulfonated aromatic amines

One of the main concerns regarding azo dyes is related to the possibility of their reduction by azoreductases, with the formation of unsulfonated aromatic amines with potential carcinogenicity. 

N Richfield-Fratz, JE Bailey, CJ Bailey. Determination of unsulfonated aromatic amines in FD C yellow no. 6 by diazotization and coupling procedure followed by reverse-phase high performance liquid chromatography J Chromatogr 331 109-123, 1985. 

Organic compounds other than coloring matters <0.5% Unsulfonated primary aromatic amines < 0.01 %, as aniline Purity (US) ... 

Azo colors comprise that largest group of certified colorants. They are characterized by the presence of one or more azo bonds (—N=N—) and are synthesized by the coupling of a diazotized primary aromatic amine to a coupling component, usually a naphthol. Certifiable azo colors can be subdivided into four groups insoluble unsulfonated pigments, soluble unsulfonated dyes, insoluble sulfonated pigments, and soluble sulfo-nated dyes. 

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