A form of Quinoline Yellow (QY, Color Index No. 47005) is certifiable in the U.S. by the Food and Drug Administration as D&C Yellow No. 10 (Y10) for use in drugs, cosmetics, and contact lenses. The EU and Australia permit QY in foods and drugs, designating it as E104. To be certified in the U.S., a QY batch must comply with specifications in the Code of Federal Regulations (CFR) for certain components and impurities. Non-CFR-specified impurities should not be present, if avoidable by Good Manufacturing Practice. This study focused on identifying an impurity present in most QY batches submitted for certification as Y10. The impurity was isolated by high-speed countercurrent chromatography from a sample of Y10 and characterised as 6-sulfo-2-quinolinecarboxylic acid (6S2QCA) by spectroscopic methods and by comparison with several synthesised isomers. All 28 Y10 batches analysed by HPLC contained 6S2QCA. Quantifiable levels ranged from 0.008% to 0.234% (mean = 0.070%).
Weisz et al. (Thu,) studied this question.