Potassium propionate

Prepared at the 49th JECFA (1997)
superseding specifications prepared at the 44th JECFA (1995),
published in FNP 52 Addendum 3 (1995)

SYNONYMS

Potassium propanoate, INS No. 283

DEFINITION

Chemical name

Potassium propionate

C.A.S. number

327-62-8

Chemical formula

C₃H₅KO₂

Structural formula

CH₃CH₂COO^-K⁺

Formula weight

112.17

Assay

Not less than 99.0 % on the dried basis

DESCRIPTION

White or colourless crystals

FUNCTIONAL USES

Preservative, antimould and antirope agent

CHARACTERISTICS

IDENTIFICATION

Solubility

Freely soluble in water, soluble in ethanol

Positive test for potassium

Passes test

Positive test for propionate

Warm the sample with sulfuric acid. The propionic acid evolved may be recognized by its odour.

Positive test for alkali salt of organic acid

Ignite the sample at a relatively low temperature. The alkaline residue effervesces with acid.

PURITY

Loss on drying

Not more than 4% (105°, 2h)

Water-insoluble matter

Not more than 0.1 %
See description under TESTS

pH

7.5 - 10.5 (1 in 10 soln)

Iron

Not more than 30 mg/kg
Test 0.5 g of the sample as described in the Limit Test using 1.5 ml of Iron Standard Solution (15 m g), in the control.

Lead

Not more than 5 mg/kg
Prepare a sample solution as directed for organic compounds in the Limit Test, using 5 m g of lead ion (Pb) in the control.

TESTS

PURITY TESTS

Water-insoluble matter

Weigh 5 g of the sample to the nearest mg, transfer into a 100-ml beaker and add 50 ml of water. Stir until all the sample appears to be completely dissolved. Filter through a Gooch crucible, tared to an accuracy of ± 0.2 mg. Rinse the beaker with 20 ml of water. Dry the crucible with its contents in a 60° oven to constant weight. Cool in a desiccator, weigh, and calculate as percentage.

METHOD OF ASSAY

Weigh, to the nearest mg, 3 g of the sample previously dried at 105° for 2 h into a distillation flask and add 200 ml of 50% phosphoric acid. Boil for 2 h and collect the distillate. During distillation keep the volume in the flask at about 200 ml by adding water using dropping funnel. Titrate the distillate with IN sodium hydroxide using phenolphthalein TS as indicator. Each ml of IN sodium hydroxide corresponds to 112.17 mg of C₃H₅KO₂.

SYNONYMS	Potassium propanoate, INS No. 283
DEFINITION
Chemical name	Potassium propionate
C.A.S. number	327-62-8
Chemical formula	C₃H₅KO₂
Structural formula	CH₃CH₂COO^-K⁺
Formula weight	112.17
Assay	Not less than 99.0 % on the dried basis
DESCRIPTION	White or colourless crystals
FUNCTIONAL USES	Preservative, antimould and antirope agent
CHARACTERISTICS
IDENTIFICATION
Solubility	Freely soluble in water, soluble in ethanol
Positive test for potassium
	Passes test
Positive test for propionate
	Warm the sample with sulfuric acid. The propionic acid evolved may be recognized by its odour.
Positive test for alkali salt of organic acid
	Ignite the sample at a relatively low temperature. The alkaline residue effervesces with acid.
PURITY
Loss on drying	Not more than 4% (105°, 2h)
Water-insoluble matter	Not more than 0.1 % See description under TESTS
pH	7.5 - 10.5 (1 in 10 soln)
Iron	Not more than 30 mg/kg Test 0.5 g of the sample as described in the Limit Test using 1.5 ml of Iron Standard Solution (15 m g), in the control.
Lead	Not more than 5 mg/kg Prepare a sample solution as directed for organic compounds in the Limit Test, using 5 m g of lead ion (Pb) in the control.
TESTS
PURITY TESTS
Water-insoluble matter	Weigh 5 g of the sample to the nearest mg, transfer into a 100-ml beaker and add 50 ml of water. Stir until all the sample appears to be completely dissolved. Filter through a Gooch crucible, tared to an accuracy of ± 0.2 mg. Rinse the beaker with 20 ml of water. Dry the crucible with its contents in a 60° oven to constant weight. Cool in a desiccator, weigh, and calculate as percentage.
METHOD OF ASSAY	Weigh, to the nearest mg, 3 g of the sample previously dried at 105° for 2 h into a distillation flask and add 200 ml of 50% phosphoric acid. Boil for 2 h and collect the distillate. During distillation keep the volume in the flask at about 200 ml by adding water using dropping funnel. Titrate the distillate with IN sodium hydroxide using phenolphthalein TS as indicator. Each ml of IN sodium hydroxide corresponds to 112.17 mg of C₃H₅KO₂.