Prepared at the 53rd JECFA (1999) and published in FNP 52 Add 7 (1999), superseding tentative specifications prepared at the 51st JECFA (1998), published in FNP 52 Add 6 (1998). Group ADI 0-0.7 mg/kg bw as SO2 for sulfites established at the 51st JECFA in 1998. |
|
SYNONYMS |
Disodium sulfite, INS No. 221 |
DEFINITION |
|
Chemical names |
Sodium sulfite |
C.A.S. number |
7757-83-7 |
Chemical formula |
Na2SO3 |
Formula weight |
126.04 |
Assay |
Not less than 95.0% |
DESCRIPTION |
White powder with not more than a faint odour of sulfur dioxide |
FUNCTIONAL USES |
Antibrowning agent, antioxidant, preservative |
CHARACTERISTICS |
|
IDENTIFICATION |
|
Solubility (FNP 5) |
Freely soluble in water; sparingly soluble in ethanol |
Test for sodium (FNP 5) |
Passes test |
Test for sulfite (FNP 5) |
Passes test |
PURITY |
|
pH (FNP 5) |
8.5 - 10.0 (1 in 10 soln) |
Thiosulfate |
Not more than 0.1% |
Iron (FNP 5) |
Not more than 10 mg/kg |
Lead (FNP 5) |
Not more than 2 mg/kg |
Selenium |
Not more than 5 mg/kg |
TESTS |
|
PURITY TESTS |
|
Selenium |
Reagents: Hydrochloric acid, hydrazinium sulfate, standard selenium solution (100 �g Se/ml) Procedure Weigh 2.0 � 0.1 g of sample and transfer to a 50-ml beaker. Add 10 ml water, 5 ml hydrochloric acid and boil to remove SO2. |
METHOD OF ASSAY |
Weigh 250 mg of the sample, add to 50.0 ml of 0.1 N iodine in a glass-stoppered flask, and stopper the flask. Allow to stand for 5 min, add 1 ml of hydrochloric acid and titrate the excess iodine with 0.1 N sodium thiosulfate, adding starch TS as the indicator. Each ml of 0.1 N iodine is equivalent to 6.302 mg of Na2SO3. |