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The natural colouring matters of foods can be isolated and identified simultaneously with the synthetic dyes by the benzalkonium method. In the course of isolation anthocyanins, carmine, betanin, caramel and riboflavin are separated from synthetic dyes, as well as from one another, with the exception of first two, which are separated from one another by chromatography or distinguished by oxidation.

A previously developed ion chromatographic method for the determination of salts in water-soluble certifiable color additives was automated, using a Model 12 Dionex ion chromatograph equipped with a program controller and programmable computing integrator. Programs were written for the program controller for continuous automated analysis of up to 59 samples in about 20 h, with periodic regeneration of the suppressor column and automatic shut-down. All data were processed through the integrator, programmed to give results in weight/weight percent. Recoveries were performed on 4 anions: chloride, phosphate, bromide, and sulfate. Twenty-five color additives could be analyzed by the method. Standard deviations in the determinations ranged from 0.01 to 0.16 at addition levels of 0.20-9.45% with 6 replications. Recoveries for addition levels of 0.2-5.0% with 2 replications fell within the range of 84.0-105.0%. Approximate lower limits of detection for each anion were as follows: chloride, 0.07%; phosphate, 0.10%; bromide, 0.06%; sulfate, 0.07%.

Two main coloring constituents in the commercial madder color were isolated and identified as ruberthric acid and lucidin-3-O-primeveroside. On quantitative analysis by high-performance liquid chromatography, the contents of ruberthric acid and lucidin-3-O-primeveroside in commercial madder color were determined 0.07% and 0.04%, respectively.

A method for the determination or 4-methylimidazole in caramel color, based on cationic separation of the sample by capillary isotachophoresis, is described. No pretreatment of the sample is necessary and the detection limit was found to be 5 ppm.

A reliable method has been developed for the rapid separation and identification of the 7 permitted FD&C dyes (Red Nos. 3 and 40; Blue Nos. 1 and 2; Yellow Nos. 5 and 6; Green No. 3) and the recently banned FD&C Red No. 2 in foods. The colors are separated by using the C18 cartridge, and their identity is confirmed by spectrophotometry.

Eighteen water-soluble food dyes have been studied by chromatography on thin layers of anion-exchange (AG 1-X4, DEAE-cellulose, PAB-cellulose and chitosan) and cation-exchange (Dowex 50-X4, Rexyn 102 and humic acid) materials; layers of silanised silica gel impregnated with cationic or anionic detergent were also used. Fourteen of the dyes were separated, but the two orange and the two black dyes were not. Some applications of the techniques to commercial products are reported.

A derivative spectroscopic method and a HPLC-method are described for the determination of the annatto dye-stuffs, norbixin and bixin, in cheese. Both methods enable a simple and quick sample preparation since the separation of beta-carotene and fat is not required. The sample preparation step consists of extraction with acetone, filtration, evaporation of the extract and separation of water residues by the addition of a few milliliters of absolute ethanol. This is followed by evaporation and extraction of the residual solution with chloroform/acetic acid (99.5 +/- 0.5) for the derivative spectroscopic method or with acetone for the HPLC method. The qualitative detection (detection limit greater than 0.67 mg/kg, depending on the genuine beta-carotene content) as well as the quantitative determination is possible by means of the derivative spectroscopic method. Therefore, this technique may be used within the rigorous Austrian regulations or for controlling the quantities and limits of annatto dye-stuffs in cheese, if its application is allowed. The method also has the advantage of quick detection (only 75 s) and saving of material used. The HPLC method allows for the separation and quantification of norbixin and bixin as well as the other carotenoids such as beta-carotene, beta-apo-8'-carotenal and beta-apo-8'-carotenoic acid--ethylester, which may also be found in varieties of cheese (detection limit of norbixin and bixin: 0.2 mg/kg). The time required for the separation of the above mentioned substances is 20 min and the HPLC method is proposed for the confirmation of low concentrations of these substances.

The rapid qualitative detection of coal tar dyes, chemicals added to color meat products, and some natural coloring materials was investigated through extraction and subsequent identification by spectrophotometric, paper chromatographic, and specific reaction techniques. These techniques will detect the presence of coal tar dyes, imidazole, histamine, histidine, cochineal, beet powder, annatto, alkanet, carotene, paprika, saffron, turmeric, and materials causing discoloration in meats.

A technique for the determination of food dyes using reversed-phase thin-layer chromatography on octadecyl-modified silica is described. A solvent system containing 5.0% aqueous sodium sulphate solution enables good separation of the food dyes. Their separation is dependent on the pH of the solvent system, good separation among all dyes being obtained between pH 6.0 and 7.0. The determination of thirteen dyes can be achieved by a combination of methanol-acetonitrile-5.0% aqueous sodium sulphate solution (3:3:10) (solvent system A) and methanol-methyl ethyl ketone-5.0% aqueous sodium sulphate solution (1:1:1) (solvent system B). Solvent system A was used for the determination of Tartrazine, Amaranth, Indigo Carmine, New Coccine, Sunset Yellow FCF, Allura Red AC, Fast Green FCF and Brilliant Blue FCF and for the screening of Acid Red (R-106), Eosin (R-103), Erythrosin (R-3), Rose Bengale (R-105) and Phloxine (R-104). When the spots of R-3, R-103, R-104, R-105 and R-106 appear on the plate, their determination can be achieved by using solvent system B. Each calibration graph was linear between 0.2 and 1.0 micrograms.

Fourteen analysts from 9 laboratories evaluated a high pressure liquid chromatographic procedure for the determination of 4,4'-(diazoamino)-dibenzenesulfonic acid (DAADBSA) in FD&C Yellow No. 6. Each collaborator analyzed 5 samples nominally containing 0-0.050% DAADBSA. The repeatability and reproducibility of the method are estimated to be 0.003% and 0.020%, respectively. The method has been adopted as offical fist action.

The authors put forward a new principle for colouration of cooked products, based on the use in the composition of the curing mixture of disodium hemin chloride (3 mg%), this enabling it to reduce the amount of the introduced nitrite down to 3 mg%. The advantage of the said curing mixtures consists also in that the sausages produced with this curing mixture did not demonstrate the presence of any residual nitrite and N-nitrose-amine compounds, whereas in control specimens (7.5 mg% of nitrite) they were present.

Biochemical degradation test of food coal-tar dyes using sludge was studied in order to evaluate their safety. It was found that some dyes were little decomposed under aerobic condition but four azo dyes were readily decomposed under anaerobic condition. These were Food Yellow No. 4, No. 5, and Food Red No. 2, No. 102. Decomposed products of these four azo dyes by sludge under anaerobic condition were identified as sulfonilic, naphthionic acids and so on.

After an introduction on the production, classification, legislative regulations, toxicology, and analysis of caramel colours, a report is given on the examination of these colourings by Curie-point pyrolysis-capillary gas chromatography-mass spectrometry. This method enables the differentiation between the four classes of caramel colours on the basis of the most concentrated of more than 100 identified pyrolysis products, which requires small quantities of substance (100 micrograms) and short periods of time (1 h).

The stability of sunset yellow FCF (E110) was investigated in a model soft drinks system, with and without the addition of sodium metabisulphite. The rate of dye degradation was monitored by spectrophotometry and HPLC. In samples containing both sunset yellow and sodium metabisulphite, the formation of a lemon-yellow-coloured compound was clearly demonstrated. Isolation and subsequent analysis by NMR and FAB-MS showed the structure of the compound to be that resulting from sulphonation at carbon 4 of the sunset yellow molecule. Examination of a stored commercial soft drinks sample indicated the presence of the same lemon-yellow compound.

Allergic reactions to food colors have been known since 1958. Reactions to tartrazine, our example, include generalized pruritus, urticaria, angioedema, paresthesias, vomiting, migraine, rhinorrhea and nasal obstruction, coughing, asthma attacks and purpura. Many patients who are allergic to antiinflammatory drugs such as acetyl-salicylic acid and indomethacin show cross-reaction to tartrazine. Doses producing these reactions range from minimal amounts up to 750 mg. Symptoms appear after periods of time ranging from minutes to 6 to 14 hours. In view of these facts (some of which represent a threat to the patient's life), additives, colouring matter, etc, do not usually appear in product labels or specifications, or in handbooks or catalogues used in practice. We drew up a list of drugs which may contain food dyes and coloring matter, yellow No. 5. A letter was written to 233 laboratories of which 159 (68%) replied. 72 (45%) in the affirmative and 87 (55%) in the negative, 74 (32%) did not reply.

A new method has been proposed for detection of lac color in food. Lac color is a natural color additive derived from a secretion of the insect Coccus Laccae (Laccifer lacca Kerr). It is extracted from food with methanolic oxalic acid and eluted from a column of Amberlite XAD-2 with the same solvent. The fraction containing the lac color is treated with diazomethane to produce 2 reddish-orange markers. The marker species in the reaction mixture are detected by both thin-layer chromatography and reverse-phase liquid chromatography.

Liquid liquid chromatography was performed with columns packed with stationary phases chemically bonded to silica microparticules. These columns show a high efficiency and are used very easily. Flavouring compounds like aromatic aldehydes which have a low volatility were analyzed in brandy using a polar phase alkylnitrile. Sapid substances like amarogentin in Gentiana lutea or glyryrrhizin in Glycyrrhiza glabra were determined by reversed phase chromatography. Finally ionizable substances like synthetic dyes can be analyzed by paired ion chromatography witha non polar stationary phase.