A method for accurately analyzing the content of Tartrazine, specifically carried out according to the following steps:
(1), take the Tartrazine sample (accurate to 0.0002 gram) of m gram (about 2 gram) in 250ml Erlenmeyer flask, add 50ml mass fraction and be 65% concentrated nitric acid, shake well, cook on electric furnace, keep slightly Boiling state for 2 hours, m≤2;
(2) Take off the Erlenmeyer flask and cool to room temperature, add 55ml of a mixed strong acid solution with a mass fraction of 65% concentrated nitric acid and a mass fraction of 71% perchloric acid with a volume ratio of 10:1, shake well, cook on an electric stove, and keep slightly Boiling state 1 hour, until the solution in the Erlenmeyer flask is light green; if not, add 65% concentrated nitric acid and 71% perchloric acid with a mass fraction of 10:1 mixed strong acid solution 22ml, Continue to heat and boil slightly until the solution is digested and turns light green;
(3) Take off the Erlenmeyer flask and cool it to room temperature, add 100ml of distilled water, and boil on an electric stove to remove excess acid in the solution until the remaining 30ml of the solution;
(4) Take off the Erlenmeyer flask, rinse the mouth of the bottle and the wall of the bottle with a small amount of distilled water, add 60ml of barium chloride solution with a concentration of 60g/L and shake well, put it on an electric stove and boil it, remove it, and cool it to room temperature. There will be white barium sulfate precipitate at the bottom of the Erlenmeyer flask. Finally, filter it with a 30ml glass sand core crucible with a known weight m0 and wash it with distilled water for 10 times until the filtrate is tested with silver nitrate and there is no white precipitate. And the pH is 6-7, otherwise continue to rinse with distilled water;
(5) Place the cleaned and precipitated glass sand core crucible in an oven at 100-105°C for 2 hours, take it out and place it in a desiccator to cool to room temperature, then weigh the total weight m1 of the crucible and the precipitate;
(6) Weigh m grams (about 2 grams) of Tartrazine sample (accurate to 0.0002 grams) into a 300ml beaker, add 150ml of distilled water, stir with a glass rod to completely dissolve the tartrazine, then add 20 grams of activated carbon, and add nitric acid Mix 1ml of nitric acid solution with a volume ratio of 1:1 to water, stir evenly, let it stand for 30 minutes, and filter it with dry filter paper. If there is still color, replace the activated carbon and re-operate;
(7) Collect all the colorless filtrates in step (6), add 30ml of barium chloride solution with a concentration of 60g/L and shake them well, put them on an electric stove and boil them, take them off, and cool them down to room temperature. White barium sulfate precipitate appears, and finally use a 30ml glass sand core crucible that has been washed and dried in advance and has a known weight m2 to suction filter, wash the precipitate with distilled water for several times, until the filtrate is tested by silver nitrate and has no white precipitate and the pH is 6‑ 7, otherwise continue to rinse with distilled water;
(8) Bake the glass sand core crucible with the cleaned sediment in step (7) in an oven at 100-105°C for 2 hours, take it out and place it in a desiccator to cool to room temperature, then weigh the total weight of the crucible and the sediment m3;
(9) Calculation: The main content of tartrazine% = {(m1‑m0)‑(m3‑m2)}×100/(0.8736×m)%
Wherein: 0.8736 is the quality of the barium sulfate that the sulfonic acid group that 1 gram 100% Tartrazine contains forms.
