» Butamben, dried over phosphorus pentoxide for 3 hours, contains not less than 98.0 percent and not more than 101.0 percent of C11H15NO2.
Packaging and storage Preserve in well-closed containers.
Completeness and color of solution One g dissolves completely in 30 mL of alcohol and in 30 mL of ether, and the solutions are colorless.
Identification, Infrared Absorption 197K.
Melting range, Class I 741: between 57 and 59.
Reaction Dissolve 1 g in 10 mL of neutralized alcohol: a clear solution results. Dilute this solution with 10 mL of water, and add 2 drops of phenolphthalein TS and 1 drop of 0.1 N sodium hydroxide: a red color is produced.
Loss on drying 731 Dry it over phosphorus pentoxide for 3 hours: it loses not more than 1.0% of its weight.
Residue on ignition 281: not more than 0.2%.
Chloride To a solution of 200 mg in 10 mL of alcohol add 1 mL of 2 N nitric acid and a few drops of silver nitrate TS: no opalescence is produced.
Heavy metals, Method I 231 Dissolve 2 g in 2 mL of 1 N acetic acid and sufficient alcohol to make 25 mL: the limit is 0.001%.
Ferrocyphen indicator solution Dissolve, without warming, 0.5 g of ferrocyphen in 50 mL of sulfuric acid.
Procedure Dissolve about 400 mg of Butamben, previously dried and accurately weighed, in a mixture of 100 mL of water and 20 mL of hydrochloric acid. Add 1 mL of Ferrocyphen indicator solution. Cool the solution in an ice bath to about 10, and titrate with 0.1 M sodium nitrite VS to a violet endpoint that is stable for not less than three minutes. Perform a blank determination, and make any necessary correction. Each mL of 0.1 M sodium nitrite is equivalent to 19.32 mg of C11H15NO2.
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USP32NF27 Page 1737