C7H5KO2 160.21

Benzoic acid, potassium salt.
Potassium benzoate [582-25-2].

Packaging and storage— Preserve in well-closed containers.

Identification— It responds to the flame test for Potassium 191 and to the tests 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%.

Organic volatile impurities, Method I 467: meets the requirements.

Residual solvents 467: meets the requirements.

Assay— Transfer about 600 mg of Potassium 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. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 16.02 mg of C7H5KO2.

Expert Committee : (EM105) Excipient Monographs 1

USP29–NF24 Page 3407

Phone Number : 1-301-816-8262