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B12-P: DETERMINATION OF NINE WATER-SOLUBLE FOOD DYES BY THE MEANS OF REVERSED-PHASE PLANAR CHROMATOGRAPHY

F. Andrić, J. Vjaković, J. Trifković, Ž. Tešić, D. Milojković-Opsenica

Faculty of Chemistry, University of Belgrade, P.O.Box 51, 11158 Belgrade, Serbia

 

     

A reversed-phase ion pair thin-layer chromatographic method for the determination of nine water-soluble foodstuff dyes: Tartrazine (E102), Quinoline Yellow (E104), Yellow orange (E110), Amaranth (E123), Ponceau 4R (E124), Eryhrozine (E127), Patent blue (E131), Indigo carmine (E132), and Brilliant blue (E133) was developed. The mobile phase containing 30 % v/v of ethanol and ammonium-sulphate as ion pair reagent in concentration of 0.7 mol dm-3 was used in combination with C-18 modified silica as a stationary phase. The horizontal and ascending developing techniques were compared. Individual zones were detected on four wavelengths: 450, 490, 520 and 625nm in order to cover in the case of horizontal technique and the scanning wavelength of 550 nm were used instead of 520 nm in the case of ascending chromatography. The validation of method was carried out thoroughly. For most of the colors good linearity was obtained in the range of 20-300 ng per spot, with correlation coefficient r > 0.9721 in the case of horizontal technique and r > 0.9509 in the case of ascending development.  In the case of E131 and E133 the range extends to the 450 ng per spot. Intra-day precision (RSD) were ranging from 0.97 % in the case of E131 (ascending method) up to 5.03 % in the case of E102, and for the horizontally developed plates: 1.36 % (E133) - 6.07 % (E132). Limit of detection varied according to the detection wavelength from 10 mg/dm3 in the case of ascending chromatography to 7 mg/dm3 for the horizontal technique. The method was applied to the determination of water-soluble colorants in various types of puddings and jelly candies.