Packaging and storage—
Preserve in well-closed, light-resistant containers.
Identification—
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.
Loss on drying 
731
—
Dry it over silica gel for 4 hours: it loses not more than 1.0% of its weight.
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%.
Organic volatile impurities, Method IV 467:
meets the requirements.
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 C
6H
6O
2.
;)
and 111