Pharmaceutical methylparaben is regulated in the use of preservatives

Specification for the use of methylparaben in preservatives [99-76-3] This product is methyl 4-hydroxybenzoate, which is made of
methanol and parabenation.
According to the calculation of dry products, the content of C8H8O3 should be 98.
0%~102.
0%.

【Properties】This product is white or off-white crystalline or crystalline powder
.
This product is soluble in methanol or ethanol, and very slightly soluble
in water.
Melting point The melting point of this product (General 0612) is 125~128 °C
.
【Identification】(1) In the chromatogram recorded under the content determination item, the retention time of the main peak of the test solution should be consistent
with the retention time of the main peak of the reference solution.
(2) take this product, add ethanol to dissolve and dilute to make about 5μg of solution per 1ml, according to ultraviolet-visible spectrophotometry (General 0401), there is a maximum absorption
at a wavelength of 258nm.
(3) The infrared light absorption spectrum of this product should be consistent
with the control spectrum (spectral set 853 figure).
【Check】Acidity take 2.
0ml of solution under the item of clarity and color of the solution, add 2ml of ethanol and 5ml of water, shake well, add 2 drops of bromocresol green indicator solution, titrate with sodium hydroxide titration solution (0.
1mol/L) to blue, and consume the volume of sodium hydroxide titration solution (0.
1mol/L) shall not exceed 0.
1ml
。 Clarity and color of the solution take 1.
0g of this product, add 10ml of ethanol to dissolve, check according to law (General rule 0901 and general rule 0902), the solution should be clear and colorless; if colored, compared with yellow or yellow-green No.
1 standard colorimetric solution (General rule 0901 first method), it should not be deeper
.
chloride take 2.
0g of this product, add 50.
0ml of water, heat in a water bath at 80 °C for 5 minutes, cool, filter; take 5.
0ml of continued filtrate, check according to law (General 0801), and compare with the control solution made of 7.
0ml of standard sodium chloride solution, it should not be more concentrated (0.
035%)
.
Sulfate take 25.
0ml of the continued filtrate under the chloride item, check according to law (General 0802), and compare with the control solution made of 2.
4ml of standard potassium sulfate solution, it shall not be more concentrated (0.
024%)
.