RU2398217C1 - Method identifying synthetic food dyes - Google Patents

Abstract

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.

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Description

The invention relates to analytical chemistry of organic compounds and can be used to identify synthetic food dyes E102, E110, E122, E124, E129, E132 in the analytical control of food products and pharmaceuticals.

The closest in technical essence and the achieved effect is a method for the identification of synthetic food colors, for example, in alcoholic beverages, including the use of a mixture of pyridine, isoamyl, isobutyl, ethyl alcohol and aqueous ammonia as an eluent [V. Bolotov. Food colors: classification, properties, analysis, application. / V.M. Bolotov, A.P. Nechaev, L.A. Sarafanova, - St. Petersburg: GIORD, 2008. - 240 p.].

The disadvantage of this method is the use of toxic solvents with a pungent odor.

An object of the invention is to develop a method for the identification of synthetic food colors E102 (Tartrazine), E110 (Sunny sunset), E122 (Azorubin), E124 (Ponso 4R), E129 (Charming Red), E132 (Indigo carmine), which allows the use of less toxic solvents and reduces detection limit.

To solve the technical problem of the invention, a method for the identification of synthetic food colors is proposed, characterized in that ammonium sulfate is added to an aqueous sample containing synthetic food colors to its concentration in a solution of 43 wt.%, Extracted with a mixture of solvents acetone - 2-propanol in a ratio of 60: 40 wt.%, When the volume ratio of the mixture of solvents and the aqueous solution is 1:10, the extract is separated, the mixture of dyes is separated by thin layer chromatography on Silufol plates, using as a mobile phase form a mixture of acetone - isobutyl alcohol, - potassium hydroxide solution with a concentration of 0.1 mol / dm ³ in a volume ratio of 0.5: 1 (0.5: 0.7), the duration of the chromatographic separation of no more than 60 minutes, colorants identified color and / or an offset coefficient, which is calculated by the formula

R _f = X / X _f ,

where X is the displacement front of the identified dye; X _f is the solvent displacement front.

The technical result consists in the almost complete extraction of synthetic food dyes with a mixture of hydrophilic solvents from a saturated aqueous solution of ammonium sulfate and the selective separation of synthetic food dyes by thin layer chromatography.

The developed method for the identification of synthetic food colors is carried out according to the following method.

To 10 cm ^{3 of an} aqueous solution containing a mixture of dyes E102, E110, E122, E124, E129, E132, crystalline ammonium sulfate is added to a salt concentration in the solution of 43%. Then, 1 cm of a mixture of acetone - 2-propanol in a ratio of 60:40 wt.% Is introduced into the mixture, extracted on a vibratory mixer for 5 minutes, the extract is separated. Dyes are identified by thin layer chromatography on Silufol plates. To do this, 0.001 cm ^{3 of the} extract is taken with a syringe, applied to the start line on a chromatographic plate, dried in air and the finish line is marked at a distance of 10 cm from the start line. At the bottom of the chromatographic chamber, acetone, isobutyl alcohol and a solution of potassium hydroxide with a concentration of 0.1 mol / dm ³ in a volume ratio of 0.5: 1: (0.5: 0.7) are placed. Chromatograph the dye mixture for 60 minutes. After the mobile phase reaches the finish line, the plate is removed from the chromatographic chamber and dried.

Dyes are identified by color and bias coefficient (R _f ), which is calculated by the equation

R _f = X / X _f ,

where X is the displacement front of the identified dye; X _f is the solvent displacement front.

96-99% of synthetic food dyes from the water-salt solution pass into the organic phase, almost complete separation of the dyes is achieved, the displacement coefficients of the known and proposed methods are shown in the table.

Examples of the method for the identification of synthetic food colors.

Example 1

To 10 cm ^{3 of an} aqueous solution containing a mixture of dyes E102, E110, E122, E124, E129, E132, crystalline ammonium sulfate is added to a salt concentration in the solution of 43%. Then, 1 cm of a mixture of acetone - 2-propanol in a ratio of 60:40 wt.% Is introduced into the mixture, extracted on a vibratory mixer for 5 minutes, the extract is separated. Dyes are identified by thin layer chromatography on Silufol plates. To do this, 0.001 cm ^{3 of the} extract is taken with a syringe, applied to the start line on a chromatographic plate, dried in air and the finish line is marked at a distance of 10 cm from the start line. At the bottom of the chromatographic chamber is placed acetone, isobutyl alcohol and a solution of potassium hydroxide with a concentration of 0.1 mol / dm ³ in a volume ratio of 0.5: 1: 0.5. Chromatograph the dye mixture for 60 minutes. After the mobile phase reaches the finish line, the plate is removed from the chromatographic chamber and dried.

Dyes are identified by color and / or bias coefficient (R _f ), which is calculated by the formula

R _f = X / X _f ,

where X is the displacement front of the identified dye; X _f is the solvent displacement front.

Achieve almost complete separation of the dyes, the color of the spots and the displacement coefficients are shown in the table.

The method is feasible.

Example 2. The identification of synthetic food colors is carried out analogously to example 1, but as the mobile phase, a mixture of acetone - isobutyl alcohol - potassium hydroxide solution with a concentration of 0.1 mol / dm ³ in a volume ratio of 0.5: 1: 0.7 is used.

Achieve almost complete separation of the dyes, the color of the spots and the displacement coefficients are shown in the table.

The method is feasible.

Table Dye (stain coloring) Offset factors Known method Example 1 Example 2 E102 (yellow) 0.27 0.16 0.22 E110 (orange) 0.39 0.33 0.41 E124 (red) 0.24 0.22 0.25 E122 (raspberry) 0.34 0.40 0.53 E129 (red) 0.50 0.36 0.44 E132 (blue) 0.36 0.26 0.36

The most selective is the system shown in example 1. Outside of the claimed intervals for the content of the components of the mixture in the mobile phase, chromatographic separation of the mixture of six synthetic food colors is not possible. The use of a mixture of acetone - 2-propanol in other ratios does not provide almost complete extraction of synthetic dyes (R <96%).

The proposed method for the identification of synthetic food dyes allows the identification of six synthetic dyes separately and in their joint presence with the use of less toxic solvents.

Claims (1)

A method for the identification of synthetic food colors, characterized in that ammonium sulfate is added to an aqueous sample containing synthetic food colors to its concentration in a solution of 43 wt.%, Extracted with a mixture of solvents acetone-2-propanol in a ratio of 60:40 wt.% With volumetric the ratio of the mixture of solvents and aqueous solution is 1:10, the extract is separated, the dye mixture is separated by thin layer chromatography on Silufol plates, a mixture of acetone - isobutyl alcohol - hydrochloride is used as the mobile phase potassium sulfide with a concentration of 0.1 mol / dm ³ in a volume ratio of 0.5: 1: 0.5-0.7, the duration of chromatographic separation is not more than 60 minutes, dyes are identified by color and / or bias coefficient, which is calculated by the formula :
R _f = X / X _f ,
where X is the displacement front of the identified dye; X _f is the solvent displacement front.