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Prepared at the 23rd JECFA (1979), published in FNP 12 (1979) and in FNP 52 (1992) |
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SYNONYMS |
Sylvine, sylvite; INS No. 508 |
DEFINITION | |
Chemical names |
Potassium chloride |
C.A.S. number |
7447-40-7 |
Chemical formula |
KCl |
Formula weight |
74.56 |
Assay |
Not less than 99.0% on the dried basis |
DESCRIPTION |
Colourless, elongated, prismatic, or cubital crystals, or white granular powder; odourless |
FUNCTIONAL USES |
Seasoning agent, gelling agent, yeast food |
CHARACTERISTICS | |
IDENTIFICATION | |
Solubility |
Freely soluble in water; insoluble in ethanol |
Test for potassium |
Passes test |
Test for chloride |
Passes test |
PURITY | |
Loss on drying |
Not more than 1% (105o, 2 h) |
Acidity or alkalinity |
To a solution of 5 g of the sample in 50 ml of recently boiled and cooled water add 3 drops of phenolphthalein TS. No pink colour is produced. Then add 0.3 ml of 0.02 N sodium hydroxide. A pink colour is produced. |
Iodide or bromide |
Dissolve 2 g of the sample in 6 ml of water, add 1 ml of chloroform, and then add, dropwise and with constant agitation, 5 ml of a mixture of equal parts of chlorine TS and water. The chloroform is free from even a transient violet or permanent orange colour. |
Test for sodium |
Negative test |
Arsenic |
Not more than 3 mg/kg (Method II) |
Heavy metals |
Not more than 10 mg/kg Test a solution of 2 g of the sample in 25 ml of water as directed in the Limit Test |
METHOD OF ASSAY |
Dissolve about 250 mg of the dried sample, accurately weighed in 50 ml of water in a glass-stoppered flask. Add, while agitating, 50 ml of 0.1 N silver nitrate, 3 ml of nitric acid, and 5 ml of nitrobenzene, shake vigorously, add 2 ml of ferric ammonium sulfate TS, and titrate the excess silver nitrate with 0.1 N ammonium thiocyanate. Each ml of 0.1 N silver nitrate is equivalent to 7.456 mg of KCl. |