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Sodium propionate

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

SYNONYMS

Sodium propanoate, INS No. 281

DEFINITION


Chemical name

Sodium propionate

C.A.S. number

137-40-6

Chemical formula

C3H5NaO2

Structural formula

CH3CH2COO-Na+

Formula weight

96.06

Assay

Not less than 99.0% on the dried basis

DESCRIPTION

White or colourless, hygroscopic crystals with not more than a faint characteristic odour

FUNCTIONAL USES

Preservative, antimould and antirope agent

CHARACTERISTICS


IDENTIFICATION


Solubility

Freely soluble in water, soluble in ethanol

Positive test for sodium

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 50 mg/kg
Test 0.5 g of the sample as described in the Limit Test using 2.5 ml of Iron Standard Solution (25 m g Fe) 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 1 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 a dropping funnel. Titrate the distillate with IN sodium hydroxide using phenolphthalein TS as indicator. Each ml of IN sodium hydroxide corresponds to 96.06 mg of C3H5NaO2.


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