TNN Determination of sodium benzoate

See the analysis method specified in gb1902-94.

Name of method: determination of sodium benzoate, neutralization titration with sodium benzoate.

Scope of application: This method uses titration to determine the sodium benzoate content.

Principle of the method: place the test sample in a separating funnel, add 25 ml of water, 50 ml of ether and 2 drops of methyl orange indicator solution, titrate with hydrochloric acid titrant (0.5 mol/l), shake with drop until a layer of water becomes visible. Orange-red; Separate the aqueous layer and pour into a stoppered conical flask. Rinse the ether layer with 5 ml of water. Pour the wash solution into a conical flask, add 20 ml of ether, continue titration with hydrochloric acid titrant (0.5 mol/l), shake with a drop, stop titration when the aqueous layer glows orange-red continuously, read the amount of hydrochloric acid and Calculate sodium benzoate content.

Reagent:

1. Water

2. Ether

3. Hydrochloric acid titrant (0.5 mol/l).

4. Methyl orange indicator solution: Take 0.1 g methyl orange and add 100 ml water to dissolve it.

Tools and equipment:

Sample preparation: 1. Hydrochloric acid titrant (0.5 mol/l).

Preparation: take 45 ml of hydrochloric acid, add the required amount of water to 1000 ml and shake well.

Calibration: Dry about {{0}}.75g standard anhydrous sodium carbonate to constant weight at 270~300 degree, add 50ml water to dissolve it, add 10 drops of methyl red and bromocresol green mixed indicator solution, titrate with this solution until the color of the solution changes from green. until purple-red, boil for 2 minutes, cool to room temperature and continue titrating until the solution changes from green to dark purple. Each 1 ml of hydrochloric acid titrant (0.5 mol/l) is equivalent to 26.5 mg of anhydrous sodium carbonate. Calculate the concentration of the solution depending on the flow rate of the solution and the amount of anhydrous sodium carbonate.

Work steps: Take about 1.5 g of this product, weigh it accurately, place it in a separatory funnel, add 25 ml water, 50 ml ether and 2 drops of methyl orange indicator solution, titrate with hydrochloric acid titrant ({{1 0}}.5 mol/l). shake with a drop until the layer of water turns orange-red; Separate the aqueous layer and pour into a stoppered conical flask. Rinse the ether layer with 5 ml of water. Place the wash solution in a conical flask, add 20 ml of ether, continue titration with hydrochloric acid titrant (0.5 mol/l), shake dropwise until the water layer turns a continuous orange-red color. Each 1 ml of hydrochloric acid titrant (0.5 mol/l) is equivalent to 72.06 mg of c7h5o2na.

Note 1: "Accurate weighing" means that the weight must be accurate to one thousandth of the weight, and "Measurement accuracy" means that the accuracy of volume measurement must meet the accuracy requirements of that volume dispenser in the national standard.