D&C Red No. 17 (R17, Colour Index No. 26100, Sudan III) is a color additive permitted in the United States for coloring externally applied drugs and cosmetics, and contact lenses. Under different names, it is also approved for use in cosmetics in the European Union (as CI 26100), Japan (as Red 225), and other countries. R17 consists mainly of 1-[[4-(phenylazo)phenyl]azo]-2-naphthalenol (<b>Sudan III</b>) with small amounts of unreacted starting materials as well as some intermediates and reaction by-products, which are produced during the manufacturing process and carried over as impurities into the final dye product. Before it may be used as a color additive, R17 is subject to batch certification by the U.S. Food and Drug Administration (FDA) to ensure compliance with specified limits for several impurities given in the U.S. Code of Federal Regulations. Among the impurities are the by-products 1-(phenylazo)-2-naphthol (Sudan I) and 1-[[2-(phenylazo)phenyl]azo]-2-naphthalenol (<b>Sudan III o-isomer</b>). The present study reports the development and application of a high-performance liquid chromatography (HPLC) method for the quantitative determination of these impurities in one analysis. Sudan III o-isomer was newly synthesized for use as reference material. The HPLC method is rapid (14 min for the total analysis) and simple to implement. It was applied to the analysis of test portions from 22 lots of D&C Red No. 17 submitted to FDA for certification.

Determination of Sudan I and of a newly synthesized Sudan III positional isomer in the color additive D&C Red No. 17 using high-performance liquid chromatography

253rd National Meeting (2017)

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