Determination of food dyes in carbonated beverages

Objective. Research and identification of food dyes in carbonated soft drinks of domestic producers. Methodology. Thin layer chromatography was used to study and identify food dyes in soft drinks. The experiments used Sorbfil TLC plates (TU26-11-17-89), aluminium foil substrate, STX1A wide-pore silica gel sorbent of 90-120 μm thickness, sorbent layer thickness variation on a plate ±5 μm, starch as binding substance; chromatography chambers; calibrated capillary or microsyringe; chemical beakers. The reagents used were test solutions of dyes; colored solutions of the analyzed carbonated beverages; the solvents (mobile phase): system A, n-propanol 100 cm3 , ethyl acetate 30 cm3 , water 30 cm3 , ammonia 1 cm3 ; and system B: acetic acid 20 cm3 , isobutane 50 cm3 , water 20 cm3 . Findings. The following carbonated soft drinks were tested in the experiment: «Mirinda» orange (manufacturer «PepsiCo»), «Fruits» orange, Isotonic, «Sokovynka» cherry («Carpathian mineral waters»), «Chambo» («Biola»). The studies were performed according to the following scheme: plate №1 - «Mirinda» orange - determination of the presence of the dye E110 (yellow «sunset»); plate №2, «Fruits» orange, determination of E102 (tartrazine); plate №3, Isotonic, determination of E132 (indigo carmine); plate №4, «Sokovynka» cherry, determination of E124 (Ponceau 4R); plate №5, «Chambo», determination of E142 (green S). The height equivalent to a theoretical plate (HETP) was found for chromatograms of all plates obtained for various test samples. HETP values for each dye were recorded. Next, the values of the mobility coefficient Rf for the dyes were calculated from the obtained chromatograms. If the mixture of the food dyes is not separated in the system A, or the Rf values of the food dyes are close, the chromatographic separation in the solvent system B was then performed. It was found that the soft drinks «Mirinda», «Fruts» and «Isotonic» contain dyes E110, E102 and E132. “Sokovynka” drink does not contain synthetic dye E124 which indicates that the color of the drink is achived by the natural dye. “Chambo” drink also does not contain the investigated dye E142, but the green color of the drink is achieved by a mixture of dyes E110 and E102. Practical value. Our proposed method of determination of dyes which was used in carbonated beverages for the determination of Tartrazine, Yellow «Sunset», Ponceau 4R can be used to identify food dyes in other foodstuffs, in particular, candy

food dyes; synthetic food dyes; carbonated soft drinks; separation factor; thin layer chromatography; height equivalent to a theoretical plate; mobility colefficient