POTASSIUM SORBATE
Prepared at the 51st JECFA (1998), published in FNP 52 Add 6 (1998)
superseding specifications prepared at the 17th JECFA (1973),
published in FNP 4 (1978) and republished in FNP 52 (1992). Group ADI
0-25 mg/kg bw for sorbic acid and its calcium, potassium and sodium
salts, expressed as sorbic acid, established at the 17th JECFA in 1973.
SYNONYMS INS No. 202
DEFINITION
Chemical names Potassium sorbate, potassium salt of trans, trans-2,4-hexadienoic acid
C.A.S. number 24634-61-5
Chemical formula C6H7KO2
Structural formula
Formula weight 150.22
Assay Not less than 98% and not more than 102% at the dried basis
DESCRIPTION White or yellowish-white crystals or crystalline powder or granules
FUNCTIONAL USES Preservative
CHARACTERISTICS
IDENTIFICATION
Solubility (Vol. 4)
Freely soluble in water; soluble in ethanol
Test for potassium (Vol. 4)
Passes test
Melting range of sorbic acid
derived from the sample
132- 135o
Acidify a solution of the sample with dilute hydrochloric acid TS. Collect
the precipitated sorbic acid on a filter paper, wash free of chloride with
water and dry under vacuum over sulfuric acid.
Test for unsaturation To 2 ml of a 1 in 10 solution of the sample, add a few drops of bromine
TS. The colour of the bromine disappears.
PURITY
Loss on drying (Vol. 4)
Not more than 1% (105º, 3 h)
Acidity or alkalinity Not more than about 1% (as sorbic acid or potassium carbonate)
Dissolve 1.1 g of the sample in 20 ml of water and add 3 drops of
phenolphthalein TS. If the solution is colourless, titrate with 0.1 N sodium
hydroxide to a pink colour that persists for 15 sec. Not more than 1.1 ml
should be required. If the solution is pink in colour titrate with 0.1 N
hydrochloric acid. Not more than 0.8 ml should be required to discharge
the pink colour.
Aldehydes Not more than 0.1% as formaldehyde
Prepare a 0.3% solution of the sample, adjust the pH to 4 with 1N HCl
and filter. To 5 ml of the filtrate add 2.5 ml of Schiff's reagent TS and
allow to stand for 10 - 15 min. Compare the colour with that produced by
5 ml of a control solution containing 15 µg of formaldehyde instead of
the sample. The colour of the test solution should not be more intense
than that of the control solution.
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, 0.25 g of the sample, previously dried at
105º for 3 h. Dissolve in 36 ml of glacial acetic acid and 4 ml acetic
anhydride in a 250-ml glass-stoppered flask, warming to effect solution.
Cool to room temperature, add 2 drops of crystal violet TS and titrate
with 0.1 N perchloric acid in glacial acetic acid to a blue-green end point
which persists for at least 30 sec. Perform a blank determination and
make any necessary correction. Each ml of 0.1 N perchloric acid is
equivalent to 15.02 mg of C6H7KO2.
POTASSIUM SORBATE
SYNONYMS
DEFINITION
Chemical names
C.A.S. number
Chemical formula
Structural formula
Formula weight
Assay
DESCRIPTION
FUNCTIONAL USES
CHARACTERISTICS
IDENTIFICATION
Melting range of sorbic acid derived from the sample
Test for unsaturation
PURITY
Acidity or alkalinity
Aldehydes
METHOD OF
ASSAY