Potassium Benzoate
C7H5KO2 160.21
Benzoic acid, potassium salt;
Potassium benzoate
[582-25-2].
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C7H5KO2 160.21
Benzoic acid, potassium salt;
Potassium benzoate
[582-25-2].DEFINITION
Potassium Benzoate contains NLT 99.0% and NMT 100.5% of potassium benzoate (C7H5KO2), calculated on the anhydrous basis.
IDENTIFICATION
• A. Identification Tests—General, Potassium 
191
and Benzoate 191:
Meets the requirements for the flame test for Potassium; meets the requirements for Benzoate
191 and Benzoate 191:
Meets the requirements for the flame test for Potassium; meets the requirements for Benzoate
ASSAY
• Procedure
Sample:
600 mg of Potassium Benzoate
Blank:
100 mL of glacial acetic acid
Titrimetric system
(See Titrimetry 541.)
541.)
Mode:
Direct titration
Titrant:
0.1 N perchloric acid VS
Endpoint detection:
Visual
Analysis:
Transfer the Sample to a 250-mL beaker. Add 100 mL of glacial acetic acid, stir until the Sample is completely dissolved, and add 2 drops of crystal violet TS. Titrate with Titrant. Perform a blank determination.
Calculate the percentage of potassium benzoate (C7H5KO2) in the portion of the Sample taken:
Result = {[(VS 
VB) × N × F]/W} × 100
VB) × N × F]/W} × 100| VS | = | = volume of Titrant consumed by the Sample (mL) |
| VB | = | = volume of Titrant consumed by the Blank (mL) |
| N | = | = actual normality of the Titrant (mEq/mL) |
| F | = | = equivalency factor, 160.2 mg/mEq |
| W | = | = weight of the Sample (mg) |
Acceptance criteria:
99.0%–100.5% on the anhydrous basis
IMPURITIES
• Heavy Metals 231
231
Test preparation:
Dilute 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.
Acceptance criteria:
NMT 10 ppm
SPECIFIC TESTS
• Alkalinity
Sample:
2 g
Analysis:
Dissolve the Sample in 20 mL in hot water, and add 2 drops of phenolphthalein TS.
Acceptance criteria:
If a pink color is produced, it is discharged by the addition of 0.20 mL of 0.10 N sulfuric acid.
• Water Determination, Method I 921:
NMT 1.5%
921:
NMT 1.5%
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Robert H. Lafaver, M.S.
Scientific Liaison 1-301-816-8335 |
(EXC2010) Monographs - Excipients |
USP35–NF30 Page 1927