Sudan dyes

Electrolytic solution Glycerol Organic solvents Benzpyrene Sudan dyes... 

Mejia, E., Ding, Y. S., Mora, M. F., and Garda, C. D. Determination of banned Sudan dyes in chili powder by capillary electrophoresis. Food Chem., 102, 1027, 2007. 

Sudan red dyes are synthetically produced dyes normally used for colouring shoe and floor polish, oils, and solvents. For example, Sudan red is used to colour petroleum products to prevent misuse. The dye is added to diesel products to prevent substitution of less expensive fuel oils. Some of the Sudan dyes have been used in the past to colour foodstuffs however, many of these, including Sudan I (see Figure 11.7), Sudan III, and Sudan IV are now banned substances. Sudan dyes have been shown to cause cancer in animal studies and thus have been declared carcinogens. They are not permitted as an additive in any foodstuff in the United Kingdom and the rest of the European Union. 

Solid phase extraction (see Chapter 3) has been successfully used to extract Sudan dyes from spices using a surface-modified polymeric-based column that has hydrophilic, hydrophobic, or tt-tt retention mechanisms. This particular phase can be used to extract both polar and nonpolar compounds. An example of a Sudan red dye is given in Figure 11.7. 

Kowalski, J. Simple HPLC analysis for Sudan dyes monitoring Sudan I, II, III, and IV in a single, isocratic analysis. Restek Chromatography Products. Available online. 

In the cat s adrenal cortex, Bennett found that yellow phenylhydra-zones and metallic silver both appeared predominantly in the outer portion of the zona fasciculata, the so-called spongy zone. These reactions failed to develop if the sections were previously extracted with acetone or ethyl alcohol at room temperature, indicating that the reactive compounds were readily soluble in such lipid solvents. In this same zone, the cells contained abundant small hpid droplets, as demonstrated with Sudan dyes or osmic acid. 

Sudan, Dyes, BASF Corp., Coatings Colorants Div. 

Sudan dyes, for example, Spices All [M-hH]" Schwack and Pellissier... 

Cationic dyes acridine orange, crystal violet, Janus green B, methyl violet, neutral red, Pyronin B, Pyronin Y (G), Safranin, Victoria blue B, and Victoria blue 4R, commonly used in histology, were studied by TLC on the Marshall and Lewis system (115). Marshall also separated some Sudan dyes, used for the histological staining of fats, on silica gel TLC sheets using benzene-CHCl3 (10 1) as the mobile phase (115). 

A new analytical method, pressurized capillary electrochromatography (pCEC) with AD using 1.5 mm reversed phase nonporous silica packed columns has been developed for the rapid separation and determination of four Sudan dyes in hot chili [36]. The influence of several experimental parameters on the retention behavior has been investigated. The electrochemical oxidation of Sudans I-FV separated by pCEC can be reliably monitored with a carbon electrode at 0.95 V (vs. Ag/AgCl). Fast and efficient separation of the analytes was achieved within 7 min by pCEC under the optimum conditions. To evaluate the feasibility and reliability of this method, the proposed pCEC-AD method was further demonstrated with hot chili samples spiked with Sudan dyes. 

A method for the analysis of such dyes has been developed. The method is based on coupling of ionic liquid-based extraction with HPLC. In this way, Sudan dyes and Para Red in chib powder, chib oil, and food additive samples can be found. 

Also, the conditions for the extraction of Sudan dyes and Para Red were optimized. Under optimal conditions, a good reproducibility of extraction performance was obtained, with relative standard deviation values of 2.0-3.5% (7). 

The ionic liquids were prepared according to a previously reported method (8,9). The Sudan dyes and Para Red standard solutions were obtained from Zhejiang Entry-Exit Inspection and Quarantine Bureau (Hangzhou, China). 

Table 1.2 Detection limits and recoveries for Sudan dyes and Para Red (7).

Water-insoluble azo dyes soluble in fats (Sudan dyes), or disperse dyes can usually be easily chromatographed on papers impregnated with organic solvents. For example, Sudan dyes are well separated in systems with paraffin oil as stationary phase (impregnation) and ethanol-water mixture (8 2) or ethanol-ammonia (8 2) as the mobile phase for obtaining rapid information papers impregnated with 50% dimethylformamide and hexane as the moving phase may be used. Dyes can be applied onto the paper in acetone solution in an amount up to 20 pg (48). 

Zhang Y, Wu HL, Xia AL, Han QJ, Cui H, Yu RQ. Interference-free determination of Sudan dyes in chilli foods using second-order cahbration algorithms coupled with HPLC-DAD. Talanta 2007 72 926-31. 

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