Acid Red 51 CAS 568-63-8

After the sample is dissolved, it is diluted, acidified, boiled, and filtered by constant weight before being weighed and calculated.

Hydrochloric acid solution: 1+49; 1+199; Instrument and equipment: G4 glass sand crucible shaped filter.

Weigh approximately 2.5g of the sample (accurate to 0.0001g), place it in a beaker, dissolve it in water, transfer it to a 250mL volumetric flask, dilute to the mark, and shake well. Take 50mL of the solution and place it in a 250mL beaker. Heat it to boiling, then add 20 mL of hydrochloric acid solution (1+49) and boil it again. Rinse the inner wall of the beaker with 5 mL of water, cover the surface dish, heat it on a boiling water bath for about 5 hours, cool it to room temperature, bake it to a constant amount at 135 ℃± 2 ℃, and cool the weighed G4 glass sand core crucible. Filter the precipitate. Rinse with 15mL hydrochloric acid solution (1+199) each time, wash twice, then rinse again with 15mL water. Bake the precipitate and G4 glass sand core crucible in a constant temperature drying oven at 135 ℃± 2 ℃ to a constant amount, cool in the dryer for 30 minutes, and weigh.

Dissolve the sample and the standard sample with known content in water, measure their absorbance at the maximum absorption wavelength, and then calculate the content of the sample.

Ammonium acetate solution; Red moss red standard sample (content ≥ 85.0%); Spectrophotometer; Color comparison dish: 10mm.

Preparation of Red Moss Red Standard Sample Solution: Weigh approximately 0.25g (accurate to 0.0001g) of Red Moss Red Standard Sample, dissolve it in an appropriate amount of water, transfer it to a 1000mL brown volumetric flask, dilute with water to the mark, and shake well. Accurately aspirate 10 mL and transfer it into a 500 mL brown volumetric flask. Dilute with ammonium acetate solution to the mark and shake well.

Preparation of Red Moss Red Sample Solution: Weighing and operating methods are the same as the preparation of standard sample solution.

Place the Acid Red 51 standard solution and the red moss red sample solution in 10mm colorimetric dishes respectively, and measure their absorbance values using a spectrophotometer at the maximum absorption wavelength. Use ammonium acetate solution as the reference solution.

The synthetic colorants in food are extracted by polyamide adsorption method or liquid-liquid distribution method, and then made into aqueous solutions. They are injected into a high-performance liquid chromatograph and separated by reverse phase chromatography. Qualitative analysis is carried out based on retention time and quantitative analysis is compared with peak area.

The minimum detection amount of synthetic colorants in food using high-performance liquid chromatography is 18ng. When the sample injection amount is 0.025g, the minimum detection concentration is 0.20.72mg/kg.

Put the prepared sample solution into a separating funnel, add 2 mL of hydrochloric acid and 10~20mL of tri-n-octylamine n-butanol solution (5%), shake and extract thoroughly, let it stand and separate the organic phase. Repeat the extraction 2-3 times, 10mL each time, until the organic phase is colorless. Combine the organic phases, wash twice with saturated sodium sulfate solution, 10mL each time, separate the organic phase, and place it in an evaporating dish. Heat and concentrate it in a water bath to 10mL, transfer it to the separating funnel, add 60mL of n-hexane, mix well, and extract 2-3 times with ammonia solution, 5mL each time. Combine the layers of ammonia solution (water-soluble acidic pigment), wash with n-hexane for 2 times. Three times, divide the ammonia water layer and add acetic acid to make it neutral. Heat and evaporate in a water bath until almost dry, and add water to make up to 5mL. Filter through a filter membrane (0.45 μ m) and take 10 μ L to enter the high-performance liquid chromatograph.

JP-303 Oscillographic Polarograph Chengdu Instrument Factory; Three electrode system with dropwise mercury electrode, saturated calomel telegraphy, platinum electrode; Bottom solution: 0.25 tool/L sodium acetate -140 mol/L hexanoic acid (pH 3.6) buffer solution; Hydrochloric acid, tri-n-octylamine, n-butanol, n-hexane, hexanoic acid; Saturated sodium sulfate solution; Ammonia solution (2+98); Red moss red standard solution (1 n~nlL).

Polarographic conditions: Take an appropriate amount of 0.10 1.00mL of the above sample extraction solution and transfer it to a 10 mL colorimetric tube with a stopper. Add the base solution to 100 mL, mix well, and pour it into an electrolytic cell for measurement. Three electrode system, cathode second derivative scanning. The initial potential is 350 mv, and the height of the polarographic derivative wave is recorded at 570] TIr~r.

Standard curve preparation: Take red moss standard solutions of 0.00, 0.50, 1.0o, 250, 5.0o, 10.0, 20.0, and 500 μ g into a 10 mL colorimetric tube for measurement.