Sodium Benzoate
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C7H5NaO2 144.10

Benzoic acid, sodium salt.
Sodium benzoate [532-32-1].
» Sodium Benzoate contains not less than 99.0 percent and not more than 100.5 percent of C7H5NaO2, calculated on the anhydrous basis.
Packaging and storage— Preserve in well-closed containers.
A: Infrared Absorption 197M, on the undried specimen.
B: It responds to the tests for Sodium 191 and for Benzoate 191.
Alkalinity— Dissolve 2 g in 20 mL of hot water, and add 2 drops of phenolphthalein TS: the pink color produced, if any, is discharged by the addition of 0.20 mL of 0.10 N sulfuric acid.
Water, Method I 921: not more than 1.5%.
Heavy metals 231 Dissolve 4.0 g in 40 mL of water, add, dropwise, with vigorous stirring, 10 mL of 3 N hydrochloric acid, and filter. Use 25 mL of the filtrate: the limit is 0.001%.
Assay— Transfer about 600 mg of Sodium Benzoate, accurately weighed, to a 250-mL beaker. Add 100 mL of glacial acetic acid, stir until the assay specimen is completely dissolved, add 2 drops of crystal violet TS, and titrate with 0.1 N perchloric acid VS to a green endpoint. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 14.41 mg of C7H5NaO2.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Robert H. Lafaver, B.A.
(EM105) Excipient Monographs 1
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 1339
Pharmacopeial Forum: Volume No. 31(3) Page 818
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.