Potassium Sorbate
(poe tas' ee um sor' bate).
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C6H7KO2 150.22
2,4-Hexadienoic acid, (E,E)-, potassium salt;    
2,4-Hexadienoic acid, potassium salt;    
Potassium (E,E)-sorbate;    
Potassium sorbate     [590-00-1; 24634-61-5].
Potassium Sorbate contains NLT 98.0% and NMT 101.0% of C6H7KO2, calculated on the dried basis.
•  A. Identification Tests—General, Potassium 191
Sample:  Dissolve 1 g of Potassium Sorbate in 10 mL of water.
Acceptance criteria:  Meets the requirements
•  B.
Sample:  0.2 g of Potassium Sorbate
Analysis:  Dissolve the Sample in 2 mL of water, and add a few drops of bromine TS.
Acceptance criteria:  The color is discharged.
•  Procedure
Sample:  300 mg of Potassium Sorbate
Blank:  40 mL of glacial acetic acid
Titrimetric system 
Mode:  Direct titration
Titrant:  0.1 N perchloric acid VS
Endpoint detection:  Visual
Analysis:  Dissolve the Sample in 40 mL of glacial acetic acid, warming, if necessary, to dissolve the solution. Cool to room temperature, and add 1 drop of crystal violet TS. Titrate with Titrant to a blue-green endpoint. Perform a blank determination.
Calculate the percentage of potassium sorbate (C6H7KO2) in the Sample taken:
Result = {[(VS VB) × N × F]/W} ×100
VS== Titrant consumed by the Sample (mL)
VB== Titrant consumed by the Blank (mL)
N== actual normality of the Titrant (mEq/mL)
F== equivalency factor, 150.2 mg/mEq
W== Sample weight (mg)
Acceptance criteria:  98.0%–101.0% on the dried basis
•  Heavy Metals, Method II 231: NMT 10 ppm
•  Acidity or Alkalinity
Sample solution:  1.1 g of Potassium Sorbate in 20 mL of water
Analysis:  Add phenolphthalein TS to the Sample solution.
Acceptance criteria:  If the solution is colorless, titrate with 0.10 N sodium hydroxide to a pink color that persists for 15 s: NMT 1.1 mL of 0.10 N sodium hydroxide is required. If the solution is pink in color, titrate with 0.10 N hydrochloric acid to discharge the pink color: NMT 0.80 mL of 0.10 N hydrochloric acid is required.
•  Loss on Drying 731: Dry a sample at 105 for 3 h: it loses NMT 1.0% of its weight.
•  Packaging and Storage: Preserve in tight containers, protected from light, and avoid exposure to excessive heat.
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
(EXC2010) Monographs - Excipients
USP35–NF30 Page 1929