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A thin layer chromatographic method is presented by which higher and lower sulfonated subsidiary dyes are simultaneously separated from FD&C Yellow No. 6. After separation, the colors are quantitated directly, using a spectrodensitometer. Recoveries of 1, 2, and 5% of added 1-(4-sulfophenylazo)-2-naphthol-3,6-disulfonic acid ranged from 92 to 111%. Recoveries of 1, 2, and 5% of added 1-(4-sulfophenylazo)-2-naphthol ranged from 90 to 110%.

Various meals being currently consumed by urban Japanese were determined for iodine. The meal samples were collected in 1982 and 1984. The habitual daily home meals of 4 middle-aged Japanese living in urban areas contained 45-1,921 micrograms (mean; 362, 361, 429 and 1,023 micrograms, respectively) of iodine per day. The regular meals served in two university hospitals contained 95-287 micrograms (mean; 195 micrograms) and 89-4,746 micrograms (mean; 1,290 micrograms) of iodine per day, respectively, and the diets for diabetes mellitus contained 59-144 micrograms (mean; 96 micrograms) of iodine per day. In the daily meals containing iodine exceeding ca. 300 micrograms, some kinds of seaweeds and, in some cases, several foods containing a red food color with low iodine bioavailability, erythrosine, provided a large portion of iodine. The iodine contents of refectory meals in a university were 47-203 micrograms (mean; 113 micrograms) per meal and those of lunches in two elementary schools were 25-31 micrograms (mean; 27 micrograms) and 18-43 micrograms (mean; 36 micrograms) per lunch, respectively. These results suggest that the current daily iodine intake of urban Japanese is not great and that erythrosine elevates the iodine content of meals.

Samples from all the British manufacturers of food grade Amaranth and Sunset Yellow FCF were examined by a densitometric thin-layer chromatographic procedure which provides a rapid and convenient method for producing a qualitative and quantitative statement on the impurity profiles of dye materials. Wide variations in the impurities were found which could account for variations in toxicological results. The method could be incorporated into official specifications to control more precisely the quality of food grade dyes.

A published procedure using Amberlite LA-2 (a liquid anion exchange resin) solutions to extract colors from food and the salt solution cellulose chromatographic technique to separate colors from each other were updated and submitted to collaborative study. Three batches of cookies and 4 purchased products were analyzed by 13 collaborators. The 3 batches of cookies contained different color mixtures requiring the selection of various procedures. The 4 purchased products were selected principally to include a variety of foods. Some results were partially deficient. The deficiencies reflect certain inadequacies in the directions as written rather than basic flaws in the method. Some improvements were suggested by the collaborators. The Assocaite Referee recommends that the method be further revised to correct the present inadequacies and to include some improvements, and that the revised method be submitted to another collaborative study.

Synthetic dyes were extracted from yogurt by different methods, but all methods had in common a liberation of dyes from the food followed by ion-pair formation with tri-n-octylamine. Extraction with pH 5.5 phosphate buffer gave high recoveries for 5 of the 7 dyes investigated and was relatively fast. Precipitation of proteins followed by polyamide adsorption and desorption gave high yields for all the dyes but was tedious and long.

Selected aromatic hydrocarbons, phthalate esters, and food, drug and cosmetic (FD&C) dyes are isolated from aqueous solutions with Chrom-Prep PRP-1 and Sep-Pak C18 cartridges. The Chrom-Prep cartridges demonstrate greater adsorption capacity for model aromatic hydrocarbons and phthalate esters than Sep-Pak C18 cartridges; however, the latter exhibits greater capacity for the FD&C dyes, which have breakthrough volumes that are a function of pH. Both cartridge types show a small amount of analyte leakage during the trace enrichment step, which is measured by monitoring the cartridge effluents for the presence of 14C-labeled solute. Two PRP-1 cartridges connected in tandem reduce the amount of activity in the effluent by approximately one half.