Method name:

Determination of Naproxen Sodium - Neutralization Titration

Application:

The method is used for the determination of Naproxen Sodium by titration.

The method is applicable to naproxen sodium.

Principle of the method:

After adding glacial acetic acid to dissolve the test material, add crystal violet indicator solution, titrate with perchloric acid titrant (0.1 mol/L) until the solution shows blue-green color, record the amount of perchloric acid titrant used, calculate, and it is obtained.

Reagents:

1. water (freshly boiled and placed at room temperature)

2. perchloric acid titrant (0.1mol/L)

3. crystalline violet indicator solution

4. glacial acetic acid

5. baseline potassium hydrogencarboxylate

Instruments and equipment:

Sample preparation:

1. Perchloric acid titrant (0.1mol/L)

Preparation: take anhydrous glacial acetic acid (according to the water content, add acetic anhydride 5.22mL per 1g water) 750mL, add perchloric acid (70%-72%) 8.5mL, shake well, add acetic anhydride 23mL slowly at room temperature drop by drop, shake while adding, and shake well after adding, cool it down, add anhydrous glacial acetic acid in appropriate amount to make it into Add 1000mL of anhydrous glacial acetic acid, shake well and leave for 24 hours. If the test product is easily acetylated, the water content of this page should be measured by water content measurement method, and then adjusted to the water content of the solution with water and acetic anhydride is 0.01%-0.2%.

Calibration: take about 0.16g of the benchmark potassium hydrogen phthalate dried to constant weight at 105℃, weigh it precisely, add 20mL of anhydrous glacial acetic acid to make it dissolve, add 1 drop of crystal violet indicator solution, titrate the solution slowly to blue, and correct the result of titration with a blank test. Each 1mL of perchloric acid titrant (0.1mol/L) is equivalent to 20.42mg of potassium hydrogen phthalate. The concentration of this solution can be calculated according to the consumption of this solution and the amount of potassium hydrogen phthalate taken.

Storage: in a brown glass bottle, tightly closed.

2. Crystalline violet indicator solution

Take 0.5g of crystalline violet, add 100mL of glacial acetic acid to dissolve, it is obtained

Operating procedure:

Weigh 0.2g of this product, add 30mL of glacial acetic acid to dissolve, add 1 drop of crystalline violet indicator solution, titrate the blue-green color of the solution with the titration solution of perchloric acid (0.1 mol/L), and correct the titration results with a blank test. Correct with blank test, record the volume of perchloric acid titrant consumed (mL), each 1mL perchloric acid titrant (0.1mol/L) is equivalent to 25.22mg of sodium naproxen (C14H13NaO3), that is obtained.

Note 1: "Precision weighing" means that the weight should be accurate to one-thousandth of the weighed weight, and "Precision measuring" means that the accuracy of the measured volume should be in accordance with the national standards for the precision of the volume pipette.

References:

Chinese Pharmacopoeia of the People's Republic of China, compiled by the State Pharmacopoeia Committee, Chemical Industry Press, 2005 edition, Part II, p. 648.