Detection of eight synthetic colorants in red wine

1. Sample information Sample component structure type lemon yellow Xinhong Amaranth Indigo Carmine Sunset yellow Temptation red Bright blue
two. Purpose

Refer to "Determination of Synthetic Colorants in Foods" (GB / T5009.35-2003) to establish an SPE-HPLC detection method for synthetic colorants in red wine.

3. Experimental method

3.1 Experimental reagents

l acetic acid;

l methanol;

l Ammonium acetate solution (0.02mol / L): Weigh 1.54g ammonium acetate, add water to dissolve and dilute to 1000mL;

l Ammonia solution: measure 2ml of ammonia water, add water to 100mL, mix well;

l Methanol / formic acid (6 + 4) solution: measure 60mL of methanol and 40mL of formic acid, mix well;

l Citric acid solution: Weigh 20g citric acid, add water to 100mL to dissolve, mix well;

l Anhydrous ethanol-ammonia solution-water: Measure 70mL of absolute ethanol, 20mL of ammonia solution and 10mL of water, and mix well;

l Water (PH = 6.0): water plus citric acid solution to adjust PH = 6.0;

l Water (PH = 4.0): water plus citric acid solution to adjust PH = 4.0;

l Water: ultrapure water

l Synthetic colorant stock solution: Each 1.0mL contains an aqueous solution of lemon yellow, new red, amaranth, indigo, carmine, sunset yellow, brilliant blue 0.5mg, temptation red 0.1mg;

l Synthetic colorant use solution: The above synthetic colorant stock solution is diluted stepwise into an aqueous solution containing 5 μg each of lemon yellow, new red, amaranth, indigo, carmine, sunset yellow, and brilliant blue in 1.0 mL, and 1 μg of lure red;

3.2. Experimental consumables

Name Specifications Order No. Venusil® XBP C18 5μm, 100A, 4.6 * 150mm VX951505-0 protection column 4.6 * 10mm, 4 / pk VX950105-0 protection column sleeve for 4.6 * 10mm protection column CH-100 Cleanert® JAX 1g / 6ml, 30 / box JXA0006 Hydrophilic PTFE 0.45um, 13mm, 100 / bag AS081345

3.3. Sample processing

Take 20ml of sample (red wine of a certain brand), add 1.0mL of synthetic colorant mixed standard solution, mix well, adjust the pH to about 6.0 with 10% ammonia water, pass all the samples through Cleanert® JAX column, and use water (PH = 4.0), Rinse with 6 mL of methanol / acid (6 + 4) solution, then rinse with 10 mL of water, elute with 6 mL of ethanol-ammonia solution-water (7 + 2 + 1), collect the eluent and evaporate to dryness in a 50 ° C water bath , Add water to bring the volume to 1.0 mL, filter through a 0.45 μm filter membrane, and wait for the test.

3.4 Liquid chromatography conditions

Column: Venusil® XBP C18, 5μm; 4.6 * 150mm;

Mobile phase: A: 0.02mol / L ammonium acetate solution (acetic acid adjusts pH = 4);

B: methanol

Flow rate: 1.0mL / min;

Injection volume: 20μL;

Wavelength: 254nm;

gradient:

Time A% B% 0 95 5 10 80 20 18 40 60 25 40 60 25.01 95 5 40 95 5

four. Experimental results

Sample Component Standards Column 1 Standards Column 2 Red Wine Sample 1 Red Wine Sample 2 Lemon Yellow 318 320 315 294 324 New Red 471 474 461 482 473 Amaranth Red 266 269 262 277 279 Indigo 314 282 279 273 275 Carmine 266 267 263 246 240 Sunset Yellow 234 238 234 210 212 Allure Red 33 33 33 35 34 Bright Blue 39 40 39 37 37 Sample component standard column 1 (%) Standard sample column 2 (%) Red wine sample 1 (%) Red wine sample 2 (%) Lemon yellow 100.6 99 92.5 102 New red 100.6 97.8 102 100 Amaranth 101 101 88.5 104 105 Indigo 89.8 88.8 86.9 87.5 Carmine 100.3 98.8 92.5 90.2 Sunset Yellow 101 100 90 90.6 Temptation Red 100 100 106 103 Bright Blue 102 100 95 95

V. Experimental conclusion

The experimental results show that Cleanert® JAX cartridges and Venusil® XBP C18 liquid chromatography columns can be used for the detection of synthetic colorants in red wine. This method is fast and accurate.

Six, matters needing attention

l The red wine sample is weakly acidic, and its pH value should be adjusted to about 6 before loading, to ensure that the small column can adsorb the synthetic colorant well;

l If the alcohol content of the sample is too high, it is recommended to remove alcohol from the sample before loading;

l During the purification of the SPE cartridge, attention should be paid to the control of the flow rate, which is recommended to be controlled at about 1mL / min;

l After the eluent is blown and reconstituted with nitrogen, it should be filtered with an aqueous filter to prevent the loss of the sample due to the adsorption of the filter. It is recommended to use the Agela Hydrophilic PTFE filter.

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