Aminobenzoic Acid
(a mee'' noe ben zoe' ik as' id).
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C7H7NO2 137.14

Benzoic acid, 4-amino.
p-Aminobenzoic acid [150-13-0].
» Aminobenzoic Acid contains not less than 98.5 percent and not more than 101.5 percent of C7H7NO2, calculated on the dried basis.
Packaging and storage— Preserve in tight, light-resistant containers.
USP Reference standards 11
USP Aminobenzoic Acid RS Click to View Structure
Solution: 5 µg per mL.
Medium: 0.001 N sodium hydroxide.
Melting range 741: between 186 and 189.
Loss on drying 731 Dry it at 105 for 2 hours: it loses not more than 0.2% of its weight.
Residue on ignition 281: not more than 0.1%.
Volatile diazotizable substances—
Standard preparation— Dissolve 10 mg of p-toluidine in 5 mL of methanol in a 100-mL volumetric flask, dilute water to volume, and mix. Transfer 1 mL to a 100-mL volumetric flask, dilute with water to volume, and mix.
Test preparation— Transfer 5.0 g of Aminobenzoic Acid to a suitable flask, and add a volume of 1.25 N sodium hydroxide that is just sufficient to dissolve the test specimen and to render the solution just alkaline to phenolphthalein TS. Dilute with water to 50 mL, and steam-distill the solution, collecting about 95 mL of the distillate in a 100-mL volumetric flask. Add water to volume, and mix.
Procedure— Transfer 20.0-mL portions of the Standard preparation and the Test preparation to separate 100-mL beakers, and transfer 20.0 mL of water to a third 100-mL beaker to provide the blank. Treat each as follows. Add 5.0 mL of 1 N hydrochloric acid, and cool in an ice bath. Add 2.0 mL of 0.1 M sodium nitrite dropwise, with stirring, allow to stand for 5 minutes in order for the diazotization reaction to be complete, add quickly to 10.0 mL of a cold solution of guaiacol (freshly prepared by dissolving 0.20 g of guaiacol in 100 mL of 1 N sodium hydroxide), mix, and allow to stand for 30 minutes. Concomitantly determine the absorbances of the solutions in 1-cm cells at the wavelength of maximum absorbance at about 450 nm, using the blank to set the instrument: the absorbance of the solution obtained from the Test preparation does not exceed that of the solution obtained from the Standard preparation, corresponding to not more than 0.002% of volatile diazotizable substances, as p-toluidine.
Ordinary impurities 466
Test solution: alcohol.
Standard solution: alcohol.
Eluant: a mixture of toluene, ethyl acetate, and alcohol (60:20:20), in a nonequilibrated chamber.
Visualization: 1.
Assay— Weigh accurately about 250 mg of Aminobenzoic Acid, and proceed as directed under Nitrite Titration 451. Each mL of 0.1 M sodium nitrite is equivalent to 13.71 mg of C7H7NO2.
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Topic/Question Contact Expert Committee
Monograph Feiwen Mao, M.S.
Senior Scientific Liaison
(SM32010) Monographs - Small Molecules 3
Reference Standards RS Technical Services
USP35–NF30 Page 2166