Sudan Red Dye Standards

By: Ingrid Hayenga, AnalytiX Volume 8 Article 4

New standards and deuterated standards for the reliable analysis of these carcinogenic compounds in foodstuffs

Senior Chemist, R&D Europe


Sudan dyes belong to a family of industrial azo-dyes used to give colour to plastics and other materials, including leather, fabrics, fats, oils, waxes, polystyrene, cellulose and synthetic lacquers and polishes. However, problems arise when the Sudan dyes are used illicitly to enhance and maintain the colour of food, especially chili and chili-derived products. In 2003, the dyes were found in chili and chili products imported from India. Since then, Sudan dyes have been detected in foods, including chili and curry powders and the processed foods that contain them, sumac, curcuma and palm oil.

Sudan Red and health

Sudan dyes are classified by the International Agency for Research on Cancer (IARC) as Group 3 carcinogens and are banned as food additives world-wide (1). In 2005 the European Food Safety Authority (EFSA) initiated a review of the toxicology of a number of dyes found illegally in food in the EU. The EFSA came to the conclusion that, especially for Sudan I, there is strong evidence for both genotoxicity and carcinogenicity. Because of structural similarities between Sudan I and the other Sudan dyes, the larger group is presumed to have the same deleterious effects (2,3).

Legislation and limits

The EU issued Decision 2003/460/EC requiring that all hot chili and hot chili products imported to Europe be tested for Sudan I. The Decision was amended in January of 2004 (2004/92/EC) to include Sudan II, III and IV. This requirement remains in effect. Although regulations do not restrict analysts to a particular analytical method, permissible levels of these dyes have generally followed the limit of quantification (LOQ) which is currently 0.5–1.0 mg/kg using LC-UV.


Part No. Description Purity Purity
51383 Sudan I > 96 % 25 mg
07937 Sudan II > 96 % 25 mg
68562 Sudan III > 96 % 25 mg
67386 Sudan IV > 96 % 25 mg
43207 Sudan Orange G > 96 % 25 mg
53373 Sudan Red 7B > 96 % 25 mg
91282 Sudan Red G > 96 % 25 mg
51602 Sudan Red B > 96 % 25 mg
34184 d5-Sudan I enrichment > 98 atom % D 10 mg
34161 d6-Sudan IV enrichment > 98 atom % D 10 mg


Table 1 Sudan Red dye standards


New Sigma-Aldrich Sudan Dye standards

Reliable reference standards are necessary to perform the analysis of Sudan dyes in foodstuffs. We have recently rounded out our line of Sudan dyes standards to include four new standards and two deuterated standards in neat form.

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  1. “Opinion of the Scientific Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food on a request from the Commission to review the toxicology of a number of dyes illegally present in food in the EU” The EFSA Journal (2005) 263, 1–71, online content:, accessed June 27, 2008.
  2. Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 8: Some Aromatic Azo Compounds, Summary of Data Reported and Evaluation, World Health Organization, International Agency for Research on Cancer (IARC). IARC website (http://monographs.iarc. fr/ENG/Monographs/vol8/volume8.pdf) accessed 27 June, 2008.
  3. “EFSA reviews toxicological data of illegal dyes in food” European Food Safety Authority (EFSA) website ( 12 September 2005, accessed 27 June, 2008.

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