Aminobenzoic Acid
(a mee'' noe ben zoe' ik as' id).
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137.14Benzoic 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
—
11—
USP Aminobenzoic Acid RS 
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Identification—
Solution:
5 µg per mL.
Medium:
0.001 N sodium hydroxide.
Melting range 741:
between 186
and 189.
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.
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%.
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.
Heavy metals, Method II 231:
0.002%.
231:
0.002%.
Ordinary impurities 466—
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.
451. Each mL of 0.1 M sodium nitrite is equivalent to 13.71 mg of C7H7NO2.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Feiwen Mao, M.S.
Senior Scientific Liaison 1-301-816-8320 |
(SM32010) Monographs - Small Molecules 3 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 2166