TNN Determination of sodium benzoate

Refer to the analysis method specified in gb1902-94.

Method name: sodium benzoate determination of sodium benzoate neutralization titration

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

Method principle: put the test sample into the separating funnel, add 25ml of water, 50ml of ether and 2 drops of methyl orange indicator solution, titrate with hydrochloric acid titrant (0.5mol / L), shake with the drop until the water layer shows orange red; Separate the water layer and put it into a corked conical flask. Wash the ether layer with 5ml of water. Incorporate the washing solution into the conical flask, add 20ml of ether, continue to titrate with hydrochloric acid titrant (0.5mol / L), shake with the drop, stop the titration when the water layer shows continuous orange red, read out the amount of hydrochloric acid titrant and calculate the content of sodium benzoate.

Reagent:

1. Water

2. Ether

3. Hydrochloric acid titrant (0.5mol/l)

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

Instruments and equipment:

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

Preparation: take 45ml hydrochloric acid, add appropriate amount of water to make it 1000ml, and shake well.

Calibration: dry about 0.75g of reference anhydrous sodium carbonate to constant weight at 270 ~ 300 ℃, add 50ml of water to dissolve it, add 10 drops of methyl red bromocresol green mixed indicator solution, titrate with this solution until the solution changes from green to purplish red, boil for 2 minutes, cool to room temperature, and continue titrating until the solution changes from green to dark purple. Every 1ml of hydrochloric acid titrant (0.5mol / L) is equivalent to 26.5mg of anhydrous sodium carbonate. Calculate the concentration of the solution according to the consumption of the solution and the amount of anhydrous sodium carbonate.

Operation steps: take about 1.5g of this product, weigh it accurately, place it in the separating funnel, add 25ml of water, 50ml of ether and 2 drops of methyl orange indicator solution, titrate with hydrochloric acid titrant (0.5mol / L), shake with the drop until the water layer shows orange red; Separate the water layer and put it into a corked conical flask. Wash the ether layer with 5ml of water. Incorporate the washing solution into the conical flask, add 20ml of ether, continue to titrate with hydrochloric acid titrant (0.5mol / L), shake with the drop until the water layer shows continuous orange red. Every 1ml of hydrochloric acid titrant (0.5mol / L) is equivalent to 72.06mg of c7h5o2na.

Note 1: "precision weighing" means that the weight should be accurate to one thousandth of the weight, and "precision measuring" means that the accuracy of measuring the volume should meet the accuracy requirements of the pipette of this volume in the national standard.