Hydroquinone
(hye'' droe kwin' one).
+'&img=../../images/v35300/g-413.gif&casNumber=123-31-9&usp=35&nf=30&chemicalStructureImage=true&ID='+parent.myID,600,500);)
110.111,4-Benzenediol.
Hydroquinone
[123-31-9].» Hydroquinone contains not less than 99.0 percent and not more than 100.5 percent of C6H6O2, calculated on the anhydrous basis.
Packaging and storage—
Preserve in tight, light-resistant containers.
USP Reference standards 
11
—
11—
USP Hydroquinone RS 
') + '&img=../../images/v35300/cas-123-31-9.gif',600,500);)
Identification—
B:
Prepare a solution of it in methanol containing approximately 1 mg per mL, and prepare a similar solution of USP Hydroquinone RS. Apply 5 µL of each solution to a suitable thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of equal volumes of methanol and chloroform until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the solvent to evaporate. Heat on a hot plate or under a lamp until spots appear: the RF value of the principal spot obtained from the solution under test corresponds to that obtained from the Standard solution.
621) coated with a 0.25-mm layer of chromatographic silica gel. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of equal volumes of methanol and chloroform until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the solvent to evaporate. Heat on a hot plate or under a lamp until spots appear: the RF value of the principal spot obtained from the solution under test corresponds to that obtained from the Standard solution.
C:
A 1 in 40,000 solution in methanol exhibits an absorbance maximum at 293 ± 2 nm.
Melting range 741:
between 172
and 174.
741:
between 172 and 174.
Water, Method I 921:
not more than 0.5%.
921:
not more than 0.5%.
Residue on ignition 281:
not more than 0.5%.
281:
not more than 0.5%.
Assay—
Dissolve about 250 mg of Hydroquinone, accurately weighed, in a mixture of 100 mL of water and 10 mL of 0.1 N sulfuric acid, add 3 drops of diphenylamine TS, and titrate with 0.1 N ceric sulfate VS until a red-violet endpoint is reached. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N ceric sulfate is equivalent to 5.506 mg of C6H6O2.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Feiwen Mao, M.S.
Senior Scientific Liaison 1-301-816-8320 |
(SM32010) Monographs - Small Molecules 3 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 3451