Specifications of Hydrous Benzoyl Peroxide USP Grade
C14H10O4 (anhydrous) --- 242.23
Peroxide, dibenzoyl.
Benzoyl peroxide --- CAS 94-36-0

Hydrous Benzoyl Peroxide contains not less than 65.0 percent and not more than 82.0 percent of C14H10O4. It contains about 26 percent of water for the purpose of reducing flammability and shock sensitivity.
Caution:Hydrous Benzoyl Peroxide may explode at temperatures higher than 60C or cause fires in the presence of reducing substances. Store it in the original container, treated to reduce static charges.

Packaging and storage: Store in the original container, at room temperature. [NOTE: Do not transfer Hydrous Benzoyl Peroxide to metal or glass containers fitted with friction tops. Do not return unused material to its original container, but destroy it by treatment with sodium hydroxide solution (1 in 10) until addition of a crystal of potassium iodide results in no release of free iodine.]
Identification:
A: Chromatograph Comparision to pass the test.
B: To pass the test.

Hydrous Benzoyl Peroxide BP Ph Eur Grade
C14H10O4 --- 242.2 --- 94-36-0
Action and use: Used topically in the treatment of acne.

DEFINITION
Content:
dibenzoyl peroxide : 70.0 per cent to 77.0 per cent;
water: minimum 20.0 per cent.

CHARACTERS
Appearance: White or almost white, amorphous or granular powder.
Solubility: Practically insoluble in water, soluble in acetone, soluble in methylene chloride with the separation of water, slightly soluble in ethanol (96 per cent).
It loses water rapidly on exposure to air with a risk of explosion.
Mix the entire sample thoroughly before carrying out the following tests.

IDENTIFICATION
First identification B.
Second identification A, C, D.
A. Ultraviolet and visible absorption spectrophotometry.
B. Infrared absorption spectrophotometry. Comparison Ph. Eur. reference spectrum of hydrous benzoyl peroxide.
C. Dissolve about 25 mg in 2 mL of acetone. Add 1 mL of a 10 g/L solution of diethylphenylenediamine sulfate and mix. A red colour develops which quickly darkens and becomes dark violet within 5 min.
D. To 1 g add 5 mL of ethanol (96 per cent), 5 mL of dilute sodium hydroxide solution and 10 mL of water. Boil the mixture under reflux for 20 min. Cool. The solution gives reaction of benzoates.

TESTS
Acidity: Dissolve a quantity of the substance to be examined containing the equivalent of 1.0 g of dibenzoyl peroxide in 25 mL of acetone, add 75 mL of water and filter. Wash the residue with two quantities, each of 10 mL, of water. Combine the filtrate and the washings and add 0.25 mL of phenolphthalein solution. Not more than 1.25 mL of 0.1 M sodium hydroxide is required to change the colour of the indicator. Carry out a blank test.
Related substances: To pass the test.
Chlorides: Maximum 0.4 per cent.