Diatrizoic Acid
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C11H9I3N2O4(anhydrous) 613.91

Benzoic acid,3,5-bis(acetylamino)-2,4,6-triiodo-.
3,5-Diacetamido-2,4,6-triiodobenzoic acid [117-96-4].

Dihydrate 649.95 [50978-11-5].
»Diatrizoic Acid is anhydrous or contains two molecules of water of hydration.It contains not less than 98.0percent and not more than 102.0percent of C11H9I3N2O4,calculated on the anhydrous basis.
Packaging and storage— Preserve in well-closed containers.Store at room temperature.
Labeling— Label it to indicate whether it is anhydrous or hydrous.
Identification—
A: It responds to the Thin-Layer Chromatographic Identification Test á201ñ,the test solution and the Standard solution being prepared at a concentration of 1mg per mLin a 0.8in 1000solution of sodium hydroxide in methanol,the solvent mixture being a mixture of chloroform,methanol,and ammonium hydroxide (20:10:2),and short-wavelength UVlight being used to locate the spots.
B: Heat about 500mg in a suitable crucible:violet vapors are evolved.
Water,Method Iá921ñ: not more than 1.0%(anhydrous form),and between 4.5%and 7.0%(hydrous form).
Residue on ignition á281ñ: not more than 0.1%.
Iodine and iodide—
Test preparation— Suspend 10.0g in 10mLof water,and add in small portions,with stirring,1.5mLof sodium hydroxide solution (2in 5).When solution is complete,adjust to a pHbetween 7.0and 7.5with a dilute solution (1in 125)of sodium hydroxide or hydrochloric acid,and dilute with water to 20mL.
Procedure— Dilute 4.0mLof Test preparationwith 20mLof water in a 50-mLcentrifuge tube provided with a stopper,and proceed as directed for Procedureunder Diatrizoate Meglumine.
Heavy metals á231ñ— To a 50-mLcolor-comparison tube transfer 2.0mLof solution prepared as directed for Test preparationin the test for Iodine and iodide,add 5mLof 1Nsodium hydroxide,dilute with water to 40mL,and mix.Using this as the Test preparation,proceed as directed in the test for Heavy metalsunder Diatrizoate Meglumine:the limit is 0.002%.
Free aromatic amine— Transfer 1.0g to a 50-mLvolumetric flask,and add 12.5mLof water and 2.5mLof 1Nsodium hydroxide.Proceed as directed in the test for Free aromatic amineunder Diatrizoate Meglumine,beginning with “To a second 50-mLvolumetric flask transfer 4mLof water.”The absorbance of the solution from the Diatrizoic Acid is not greater than that of the Standard solution (0.05%).
Assay— Transfer about 300mg of Diatrizoic Acid,accurately weighed,to a glass-stoppered,125-mLconical flask,and proceed as directed in the Assayunder Diatrizoate Meglumine,beginning with “add 30mLof 1.25Nsodium hydroxide.”Each mLof 0.05Nsilver nitrate is equivalent to 10.23mg of C11H9I3N2O4.
Auxiliary Information— Staff Liaison:Andrzej Wilk,Ph.D.,Senior Scientific Associate
Expert Committee:(RMI)Radiopharmaceuticals and Medical Imaging Agents
USP28–NF23Page 617
Phone Number:1-301-816-8305