METHOD IDENTIFYING SYNTHETIC FOOD DYES Russian patent published in 2010 - IPC G01N21/25 C09B61/00 

FIELD: chemistry.

SUBSTANCE: water sample containing synthetic food dyes is mixed with ammonium sulphate until achieving its concentration in the solution of 43 wt %. The mixture is extracted with a mixture of acetone - 2-propanol solvents in ratio of 60:40 wt % in volume ratio of the mixture of solvents to the aqueous solution equal to 1:10. The extract is separated. The mixture of dyes separated through thin layer chromatography on Silufol plates. The mobile phase used is a mixture of acetone-isobutyl alcohol-potassium hydroxide solution with concentration of 0.1 mol/dm³ in volume ratio of 0.5:1:0.5-0.7. Chromatographic separation takes not more than 60 minutes. The dyes are identified from colour and/or shift factor which is calculated using the formula: R_f = X/X_f, where X the shift front of the identified dye; X_f is the shift front of the solvent.

EFFECT: proposed method enables identification of six synthetic dyes E102 Tartrazine, E110 Sunset Yellow, E122 Azorubine, E124 Ponceau 4R, E129 Allura red, E132 Indigo Carmine separately or in a mixture using less toxic solvents and reduction of the detection level.

1 cl, 1 tbl, 2 ex