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% |
pH |
7.5 - 10.5 (1 in 10 soln) |
Iron |
Not more than 50 mg/kg |
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. |