Analysis of Food Coal-Tar Dyes in Commercial Dairy Product, Soft Drink, Child Food, Pickle and Vegetarian Food

JIIN-FUNG SHYU, AH-SHIH LEE AND JASON DALANG HONG

National Laboratories of Foods and Drugs, Department of Health, Executive Yuan. 161-2, Kuen Yang Street, Nan Kang, Taipei, Taiwan, R.O.C.

ABSTRACT

   A TLC analysis of coal-tar dyes in 62 dairy products, 67 soft drinks, 76 child foods, 57 pickles and 55 vegetarian foods were performed. Samples were extracted by the appropriate solvent according to the required methods. Then were diluted three fold with water, adsorbed in a polyamide column, and re-dissloved from column by a mixture of 1-3% ammonia water and methanol. The eluent was concentrated and was analyzed by TLC method with Cellulose TLC plate, the mobile phase was solublized in n-Butanol/Ethanol/l% Ammonia water(6 : 2 : 3) or n-Butanol/Ethanol/0.5 N Acetic acid (6 : 2 : 3). The results showed a good reproducibility and most of samples qualifiable to meet the requirement of sanitary regulations, except 6 samples of pickels contained yellow coal-tar dye and 5 samples of vegetarian foods contained tartrazine and green coal-tar dye which the official regulation does not permit.

Key words: Coal-Tar Dye, Cellulose Thin Layer Plate, Silica Gel Thin Layer Plate, Polyamide.