Sorbic Acid
(sor' bik as' id).
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C6H8O2 112.13
2,4-Hexadienoic acid, (E,E)-; 2,4-Hexadienoic acid;    
(E,E)-Sorbic acid; Sorbic acid     [110-44-1].
Sorbic Acid contains NLT 99.0% and NMT 101.0% of C6H8O2, calculated on the anhydrous basis.
•  B. A 1-in-400,000 solution in isopropyl alcohol exhibits an absorbance maximum at 254 ± 2 nm.
•  Procedure
Sample solution:  Dissolve 250 mg of Sorbic Acid in a mixture of 50 mL of methanol and 25 mL of water that previously has been neutralized with 0.02 N sodium hydroxide. Add phenolphthalein TS.
Analysis:  Titrate with 0.1 N sodium hydroxide VS to the first pink color that persists for at least 30 s. Each mL of 0.1 N sodium hydroxide is equivalent to 11.21 mg of C6H8O2.
Acceptance criteria:  99.0%–101.0% on the anhydrous basis
Inorganic Impurities 
•  Residue on Ignition 281: NMT 0.2%
•  Packaging and Storage: Preserve in tight containers, protected from light, and avoid exposure to excessive heat.
•  USP Reference Standards 11
USP Sorbic Acid RS
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Monograph Robert H. Lafaver, M.S.
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(EXC2010) Monographs - Excipients
Reference Standards RS Technical Services
USP35–NF30 Page 1963
Pharmacopeial Forum: Volume No. 36(4) Page 951