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Methyl Paraben Sodium B.P.

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Chemical Name Sodium Methyl 4-Hydroxybenzoate
 Molecular Formula C8H7NaO3
 Molecular Weight 174.1

 Structural Formula
 CAS Number 5026-62-0
 Packing 25 Kg, 20kg(4 x 5 kg)
 The Shelf-life 3 years
 Storage conditions and precautions Store in a well-closed containers.
 Characters A white, crystalline powder, freely soluble in water, sparingly soluble in alcohol, practically insoluble in methylene chloride.

First identification A, B, E

Second identification A, C, D, E

A.       Dissolve 0.5 g in 50 ml of water R. Immediately adds 5ml of hydrochloric acid R1. Filter and wash the precipitate with water R. Dry under vacuum at 80oC for 2 hours. The precipitate obtained melts (2.2.14) at 125°C to 128°C.

B.       Examine the precipitate obtained in identification test A by infrared absorption spectrophotometry (2.2.24) comparing with the spectrum obtained with methyl parahydroxy benzoate CRS.

C.      Examine the chromatograms obtained in the test for related substances. The principal spot in the chromatogram obtained with test solution (b) is similar in position and size to the principal spot in the chromatogram obtained with reference solution (c).

D.      To about 10 mg in a test-tube add 1 ml of sodium carbonate solution R, boil for 30s and cool. Add 5 ml of aminopyrazolone solution R and 1 ml of potassium ferricyanide solution R and mix. An orange to red colour develops.

E.   To 1 ml of Solution S (see Tests) add 1 ml of water R. The solution gives reaction (a) of sodium (2.3.1)

3. Appearance of solution Dissolve 5 gm in carbon-dioxide free water R prepared from distilled water R and dilute to 50 ml examine immediately after preparation is clear (2.2.1) and not more intensely coloured than reference solution BY6 (2.2.2, Method I).
4. pH Between 9.5 to 10.5 (1 gm in 1000 ml carbon-dioxide free water)
5. Related substances

Impurity A: any spot due to impurity A is not more intense than the spot in the Chromatogram obtained with reference solution (a) (4 %)

Any other impurity: Any spot, apart from the principal spot and due to 4-hydroxy benzoic acid is not more intense than the spot in the chromatogram obtained with reference solution (b) (0.5 %)

System suitability: The test is not valid unless the chromatogram obtained with reference solution (d) shows two clearly separated principal spots.

6. Chlorides Not more than 350 ppm.
7. Sulphate Not more than 300 ppm.
8. Heavy Metals Not more than 10 ppm.
9. Water Not more than 5.0%.
10. Assay Not less than 99.0% to not more than 102.0% of sodium 4-(methoxycabonyl) Phenolate, calculated with reference to the anhydrous substance.  
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