SYNONYMS INS No. 202
Chemical names Potassium sorbate, potassium salt of trans, trans-2,4-hexadienoic acid
C.A.S. number 24634-61-5
Chemical formula C6H7KO2
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
Freely soluble in water; soluble in ethanol
Test for potassium
Melting range of sorbic acid
derived from the sample
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.
Loss on drying
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
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 colour of the test solution should not be more intense
than that of the control solution.
Not more than 2 mg/kg
Determine using an atomic absorption technique appropriate to the
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.