Pharmaceutical grade methylparaben 500 g of methylparaben is available in batches

Pharmaceutical grade methylparaben 500 g of methylparaben has a batch [check] acidity Take the clarity and color of the solution under the solution 2.
0ml, add ethanol 2ml and water 5ml, shake well, add 2 drops of bromocresol green indicator solution, titrate with sodium hydroxide titration solution (0.
1mol / L) to appear blue, consume the volume of sodium hydroxide titration solution (0.
1mol / L) shall not exceed 0.
1ml
.

The clarity and color of the solution Take 1.
0g of this product, add ethanol 10ml to dissolve, check according to law (general rule 0901 and general rule 0902), the solution should be clear and colorless; such as color rendering, compared with yellow or yellow-green No.
1 standard colorimetric solution (general rule 0901 first law), must not be deeper
.

Chloride Take 2.
0g of this product, add 50.
0ml of water, heat it in a water bath at 80 ° C for 5 minutes, let it cool, filter it; take 5.
0ml of filtrate, check according to law (general 0801), and compare with the control solution made of standard sodium chloride solution of 7.
0ml, no more concentrated (0.
035%)
.

Sulfate Take 25.
0ml of the sub-filtrate under the chloride, check according to law (general 0802), and compare with the control solution made of standard potassium sulfate solution of 2.
4ml, no more concentrated (0.
024%)
.

Relevant substances Take an appropriate amount of this product, weigh it precisely, add a mobile phase to dissolve and quantitatively dilute it to make a solution containing about 1 mg per 1 ml as a test solution; Take 1 ml of precision, place it in a 100 ml measuring flask, dilute it to the scale with the mobile phase, shake well, as a control solution; Take an appropriate amount of parahydroxybenzoic acid control, weigh it precisely, add the mobile phase to dissolve and quantitatively dilute it to make a solution containing about 3 μg per 1 ml as a control solution; Take 5 ml of the control solution, place it in a 50 ml measuring flask, dilute it to the scale with the mobile phase, shake well, and use it as a sensitivity solution
.

According to the chromatographic conditions under the content determination, take 20 μl of the sensitivity solution and inject it into the liquid chromatograph, and the signal-to-noise ratio of the parahydroxybenzoic acid peak should be greater than 20
.

Then take 20 μl of the test solution, control solution and control solution, inject it into the liquid chromatograph respectively, and record the chromatogram to 4 times
the retention time of the main peak.

If there is a peak in the chromatogram of the test solution that is consistent with the peak retention time of the parahydroxybenzoate, the peak area shall not exceed 0.
3% according to the external standard method, and the peak area of other individual impurities shall not be greater than 0.
4 times (0.
4%) of the main peak area of the control solution, and the peak area of each impurity shall not be greater than 0.
8 times (0.
8%)
of the main peak area of the control solution.

Loss of weight to dry Take this product, placed in a silicone dryer, dry under reduced pressure to constant weight, and the weight loss shall not exceed 0.
5% (General 0831).
Blazing residue Take 1.
0g of this product, check according to law (General Principle 0841), and the residual residue shall not exceed 0.
1%.