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A SYSTEMATIC METHOD FOR IDENTIFICATION OF FOOD, DRUG AND COSMETIC AZO DYES BY Jos•. M. PL•-DELFINA* TSE water-soluble monoazo colors probably are the dyes used most frequently in foods, drugs and cosmetics, except that specific forms of the latter may require pigments. These dyes appear repeatedly in all inter- national lists of permitted colors, monoazo dyes comprising ahnost 80 per cent of all the listed dyes. Although paper chromatography alone can sometimes be used to separate and identify the principal "universal" food colors (1, 2, 3), the use of so simple an analytical procedure becomes insufficient if drugs and cosmetics are added to the list. Such an increase in the number of dyes and their interactions necessitates the use of complementary methods of analysis, solvent extraction, column chromatography, chemical color reactions, etc., for effective separation (4, 5, 6). An attempt was made in our laboratory to develop a simple systematic, wholly paper chromatographic method for at least a limited group of dyes. The results reported below show that such a method is feasible for all im- portant water-soluble food, drug and cosmetic monoazo dyes. After a review of the principal legislative trends (7-13) as well as of in- ternational classification codes (14-17) and of special literature (18-22), we have concluded that all important monoazo colors are listed in Table 1, which also includes their chemical constitution and their status f*or food, drug and cosmetic use in several countries. The authorities for this tabu- lation have been the following: a) British list of the "Food Standards Committee" (F.S.C.). b) German list of the "Deutsche Forschungsgemeinscbaft" (D.F.G.). c) List of the United States "Food and Drug Administration" (F.D.A.). d) French version of the proposed cosmetic list for European Common Market (12). e) Spanish list for foods and food packaging. With the help of several commercial firms,•' it was possible to obtain * Practical Pharmacy Dept. (C.S.I.C.), University of Barcelona, Spain. •' The samples were available by courtesy of the firms Azamon, Ciba, Sandoz, Geigy, Rovira, Bachs y Macia and Unicolor. 214