POTASSIUM BENZOATE-苯甲酸钾

POTASSIUM BENZOATE Prepared at the 46th JECFA (1996), published in FNP 52 Add 4 (1996) superseding specifications prepared at the 17th JECFA (1974), published in FNP 4 (1978). Metals and arsenic specifications revised at the 63rd JECFA (2004). A group ADI of 0-5 mg/kg bw for benzoic acid and salts was established at the 27th JECFA (1983) and maintained at the 46th JECFA (1996). SYNONYMS INS No. 212 DEFINITION Chemical names Potassium benzoate, potassium salt of benzenecarboxylic acid, potassium salt of phenylcarboxylic acid C.A.S. number 582-25-2 (anhydrous) Chemical formula C7H5KO2 · 3H2O Structural formula Formula weight 160.22 (anhydrous) 214.27 (trihydrate) Assay Not less than 99.0% on the dried basis DESCRIPTION White crystalline powder FUNCTIONAL USES Antimicrobial preservative CHARACTERISTICS IDENTIFICATION Solubility (Vol. 4) Freely soluble in water, soluble in ethanol Test for benzoate (Vol. 4) Passes test Use a 10% solution of the sample Test for potassium (Vol. 4) Passes test Use a 10% solution of the sample PURITY Loss on drying (Vol. 4) Not more than 26.5% (105o, 4 h) Acidity or alkalinity Dissolve 2 g of the sample, weighed to the nearest mg, in 20 ml of freshly boiled water. Not more than 0.5 ml of either 0.1N sodium hydroxide or 0.1N hydrochloric acid should be required for neutralization, using phenolphthalein TS as indicator. Readily carbonizable substances Dissolve 0.5 g of the sample, weighed to the nearest mg, in 5 ml of sulfuric acid TS. The colour produced should not be darker than a light pink ("Matching Fluid Q") Chlorinated organic compounds (Vol. 4) Not more than 0.07% (as chlorine) Test 0.25 g of the sample using 0.5 ml of 0.01N hydrochloric acid in the control Readily oxidizable substances Add 1.5 ml of sulfuric acid to 100 ml of water, heat to boiling and add 0.1N potassium permanganate, dropwise, until the pink colour persists for 30 sec. Dissolve 1 g of the sample, weighed to the nearest mg, in the heated solution, and titrate with 0.1N potassium permanganate to a pink colour that persists for 15 sec. Not more than 0.5 ml should be required. Lead (Vol. 4) Not more than 2 mg/kg Determine using an atomic absorption technique appropriate to the specified level. The selection of sample size and method of sample preparation may be based on the principles of the method described in Volume 4, “Instrumental Methods.” METHOD OF ASSAY Weigh to the nearest 0.1 mg, 2.5 to 3 g of the dried sample, and transfer to a 250-ml Erlenmeyer flask. Add 50 ml of water to dissolve the sample. Neutralize the solution, if necessary, with 0.1N hydrochloric acid, using phenolphthalein TS as indicator. Add 50 ml of ether and a few drops of bromophenol blue TS and titrate with 0.5N hydrochloric acid, shaking constantly the flask, until the colour of the indicator begins to change. Transfer the lower aqueous layer to another flask. Wash the ethereal layer with 10 ml of water, and add the washing and an additional 20 ml of ether to the separated aqueous layer. Complete the titration with the 0.5N hydrochloric acid, shaking constantly the flask. Each ml of 0.5N hydrochloric acid is equivalent to 80.11 mg of C7H5KO2. POTASSIUM BENZOATE SYNONYMS DEFINITION Chemical names C.A.S. number Chemical formula Structural formula Formula weight Assay DESCRIPTION FUNCTIONAL USES CHARACTERISTICS IDENTIFICATION PURITY Acidity or alkalinity Readily carbonizable substances Readily oxidizable substances METHOD OF ASSAY