Development of a Fast Analytical Method for the Determination of Sudan Dyes in Chili- and Curry-Containing Foodstuffs by High-Performance Liquid Chromatography-Photodiode Array Detection VANESSA CORNET,* YASMINE GOVAERT,GOEDELE MOENS, JORIS VAN LOCO, AND JEAN-MARIE DEGROODT Department of Pharmaco-bromatology, Food Section, Institute of Public Health, J. Wytsmanstreet 14, 1050 Brussels, Belgium A simple and fast analytical method for the determination of sudans I, II, III, and IV in chili- and curry-containing foodstuffs is described. These dyes are extracted from the samples with acetonitrile and analyzed by high-performance liquid chromatography coupled to a photodiode array detector. The chromatographic separation is carried out on a reverse phase C 18 column with an isocratic mode using a mixture of acetonitrile and water. An “in-house” validation was achieved in chili- and curry- based sauces and powdered spices. Depending on the dye, limits of detection range from 0.2 to 0.5 mg/kg in sauces and from 1.5 to 2 mg/kg in spices. Limits of quantification are between 0.4 and 1 mg/kg in sauces and between 3 and 4 mg/kg in spices. Validation data show a good repeatability and within-lab reproducibility with relative standard deviations < 15%. The overall recoveries are in the range of 51-86% in sauces and in the range of 89-100% in powdered spices depending on the dye involved. Calibration curves are linear in the 0-5 mg/kg range for sauces and in the 0-20 mg/kg range for spices. The proposed method is specific and selective, allowing the analysis of over 20 samples per working day. KEYWORDS: Sudan dyes; chili- and curry-containing foodstuffs; HPLC-PDA; food safety INTRODUCTION A lot of dyes are used as food additives and include both natural and synthetic substances, covering a wide range of chemical entities. The most common artificial food colors are azo dyes. The list of authorized food colors and the maximum permitted levels in foodstuffs are laid down in the annexes of Council Directive 94/36/EC (1). Other azo dyes such as the sudan dyes are nonauthorized and are illegally used in the food industry to enhance and maintain the appearance of food products. Sudans I, II, III, and IV are phenyl-azoic derivatives widely used in chemical industries for coloring materials such as hydrocarbon solvents, oils, fats, plastics, printing inks, and shoe and floor polishes. Their chemical structures are illustrated in Figure 1. Repeated notifications about the detection of the nonauthorized sudan dyes in foods have been disseminated by the European Union rapid alert system since 2003. On the 9th of May 2003, French sanitary authorities detected sudan I in hot chili products imported from India (2). As sudan I is classified as a category 3 carcinogen by the International Agency for Research on Cancer (IARC) and as a category 3 mutagen in Annex I of the Council Directive 67/548/EEC (3-6), this synthetic dye constitutes a potential risk for public health if it enters the food chain. Except in some African or Asian countries, their use as additives, at any level, in food products destined for human consumption is prohibited worldwide. Consequently, the Commission Decision 2005/402/EC (7) requires that all chili-, curry-, and curcuma-containing food products and palm oil coming into any European Union member state are certified to be free of sudan dyes. Since July 2003, more than 160 products have been recalled for destruction in the United Kingdom because of the detection of sudan dyes. As the illegal use of dyes has major economic consequences for most European Union food industries as well as an impact on public health, suitable analytical screening and confirmatory methods are required for compliance verification of these foodstuffs. At this moment, very few analytical methods have been described in the literature. A method including a Soxtec extraction and a gel permeation chromatography cleanup followed by high- performance liquid chromatography (HPLC) with ultraviolet/ visible detection has been recently proposed by Mazzetti et al. for the detection of sudan I in chili powder and chili-containing food products (8). A second method using thin-layer chroma- tography has been developed for the qualitative analysis of sudans I, II, III, and IV in palm oil (9). The scope of these two * To whom correspondence should be addressed. Tel: +32 2 642 51 25. Fax: +32 2 642 56 91. E-mail: vanessa.cornet@iph.fgov.be. J. Agric. Food Chem. 2006, 54, 639-644 639 10.1021/jf0517391 CCC: $33.50 © 2006 American Chemical Society Published on Web 01/13/2006