Iopanoic Acid
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C11H12I3NO2 570.93

Benzenepropanoic acid, 3-amino--ethyl-2,4,6-triiodo-, (±)-.
(±)-3-Amino--ethyl-2,4,6-triiodohydrocinnamic acid [96-83-3].
» Iopanoic Acid contains an amount of iodine equivalent to not less than 97.0 percent and not more than 101.0 percent of C11H12I3NO2, calculated on the dried basis.
Packaging and storage— Preserve in tight, light-resistant containers.
Identification— Mix about 100 mg with 500 mg of sodium carbonate in a crucible, and heat until thoroughly charred. Cool, add 5 mL of hot water, heat on a steam bath for 5 minutes, and filter: the solution responds to the tests for Iodide 191.
Melting range 741: between 152 and 158, with decomposition.
Loss on drying 731 Dry it at 105 for 1 hour: it loses not more than 1.0% of its weight.
Residue on ignition 281: not more than 0.1%.
Free iodine— Shake about 200 mg with 2 mL of water and 2 mL of chloroform for 1 minute: the chloroform layer shows no violet color.
Halide ions— Place about 500 mg in a glass-stoppered, 50-mL cylinder, add 10 mL of 2 N nitric acid and 15 mL of water, shake for 5 minutes, and filter through paper: 10 mL of the filtrate shows no greater turbidity than corresponds to 0.05 mL of 0.020 N hydrochloric acid (see Chloride and Sulfate 221).
Assay— Transfer about 250 mg of Iopanoic Acid, accurately weighed, to a glass-stoppered, 250-mL conical flask. Add 30 mL of 1.25 N sodium hydroxide and 500 mg of powdered zinc, and reflux the mixture for 30 minutes. Cool to room temperature, wash the condenser with 20 mL of water, and filter the mixture. Wash the flask and the filter with small portions of water, adding the washings to the filtrate. Add to the filtrate 5 mL of glacial acetic acid and 1 mL of tetrabromophenolphthalein ethyl ester TS, and titrate with 0.05 N silver nitrate VS until the color of the yellow precipitate just changes to green. Each mL of 0.05 N silver nitrate is equivalent to 9.516 mg of C11H12I3NO2.
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Topic/Question Contact Expert Committee
Monograph Ian DeVeau, Ph.D.
Director, Veterinary Drugs and Radiopharmaceuticals
(RMI05) Radiopharmaceuticals and Medical Imaging Agents 05
USP32–NF27 Page 2670