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 sulfite established at the 51st JECFA in 1998. | |
SYNONYMS |
INS No. 223 |
DEFINITION |
|
Chemical names |
Sodium disulfite, disodium pentaoxodisulfate, disodium pyrosulfite |
C.A.S. number |
7681-57-4 |
Chemical formula |
Na2S2O5 |
Formula weight |
190.11 |
Assay |
Not less than 90.0% |
DESCRIPTION |
White crystals or crystalline powder having an odour of sulfur dioxide |
FUNCTIONAL USES |
Antibrowning agent, antioxidant, flour treatment agent, preservative |
CHARACTERISTICS |
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IDENTIFICATION |
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Solubility (FNP 5) |
Freely soluble in water; slightly soluble in ethanol |
Test for sodium (FNP 5) |
Passes test |
Test for sulfite (FNP 5) |
Passes test |
PURITY |
|
Water insolubles |
Dissolve 20 g of the sample in 200 ml of water. The solution should be clear with only a trace of suspended matter |
pH (FNP 5) |
4.0 - 4.5 (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 |
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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 0.2 g of the sample to the nearest mg, 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 4.753 mg of Na2S2O5. |