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C6H6O2 110.11

Resorcinol [108-46-3].
» Resorcinol contains not less than 99.0 percent and not more than 100.5 percent of C6H6O2, calculated on the dried basis.
Packaging and storage— Preserve in well-closed, light-resistant containers.
A: Infrared Absorption 197K[note—If necessary to recrystallize, dissolve in dehydrated alcohol.]
B: Dissolve 100 mg in 2 mL of 1 N sodium hydroxide, add 1 drop of chloroform, and heat the mixture: an intense crimson color is produced. Then add a slight excess of hydrochloric acid: the color changes to pale yellow.
C: To 10 mL of a solution (1 in 100) add 1 drop of ferric chloride TS: a blue-violet color is produced, and it fades slowly.
Melting range 741: between 109 and 111.
Loss on drying 731 Dry it over silica gel for 4 hours: it loses not more than 1.0% of its weight.
Residue on ignition 281: not more than 0.05%.
Phenol— Heat gently a solution (1 in 20): the odor of phenol is not perceptible.
Catechol— To 10 mL of a solution (1 in 20) previously mixed with 2 drops of 1 N acetic acid add 0.5 mL of lead acetate TS: no turbidity is produced.
Ordinary impurities 466
Test solution: methanol.
Standard solution: methanol.
Eluant: a mixture of hexanes and ethyl acetate (70:30).
Visualization: 17 and then 1.
Application volume: 10 µL.
Limits: not more than 1.0%.
Assay— Dissolve about 1.5 g of Resorcinol, accurately weighed, in water to make 500.0 mL. Transfer to an iodine flask 25.0 mL of the resulting solution, add 50.0 mL of 0.1 N bromine VS, dilute with 50 mL of water, add 5 mL of hydrochloric acid, and at once insert the stopper in the flask. Shake for 1 minute, allow to stand for 2 minutes, and add 10 mL of potassium iodide TS while slightly loosening the stopper. Shake thoroughly, allow to stand for 5 minutes, remove the stopper, and rinse it and the neck of the flask with 20 mL of water into the flask. Titrate the liberated iodine with 0.1 N sodium thiosulfate VS, adding starch TS as the endpoint is approached. Perform a blank determination. From the volume of 0.1 N sodium thiosulfate VS used, calculate the volume, in mL, of 0.1 N bromine VS consumed by the resorcinol. Each mL of 0.1 N bromine is equivalent to 1.835 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.
(MDOOD05) Monograph Development-Ophthalmics Oncologics and Dermatologicals
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 3494
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.