Hydroquinone
;)
1,4-Benzenediol.
Hydroquinone [123-31-9].
»Hydroquinone contains not less than 99.0percent and not more than 100.5percent of C6H6O2,calculated on the anhydrous basis.
Packaging and storage—
Preserve in tight,light-resistant containers.
Identification—
A:
Infrared Absorption á197Kñ.
B:
Prepare a solution of it in methanol containing approximately 1mg per mL,and prepare a similar solution of USP Hydroquinone RS.Apply 5µLof each solution to a suitable thin-layer chromatographic plate (see Chromatography á621ñ)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 RFvalue of the principal spot obtained from the solution under test corresponds to that obtained from the Standard solution.
C:
A1in 40,000solution in methanol exhibits an absorbance maximum at 293±2nm.
and 174
Water,Method Iá921ñ:
not more than 0.5%.
Residue on ignition á281ñ:
not more than 0.5%.
Organic volatile impurities,Method Iá467ñ:
meets the requirements.
Assay—
Dissolve about 250mg of Hydroquinone,accurately weighed,in a mixture of 100mLof water and 10mLof 0.1Nsulfuric acid,add 3drops of diphenylamine TS,and titrate with 0.1Nceric sulfate VSuntil a red-violet endpoint is reached.Perform a blank determination,and make any necessary correction.Each mLof 0.1Nceric sulfate is equivalent to 5.506mg of C6H6O2.
Auxiliary Information—
Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist
Expert Committee:(PA6)Pharmaceutical Analysis 6
USP28–NF23Page 974
Phone Number:1-301-816-8389