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 |
INS No. 225 |
DEFINITION |
|
Chemical names |
Potassium sulfite |
C.A.S. number |
10117-38-1 |
Chemical formula |
K2SO3 |
Formula weight |
158.25 |
Assay |
Not less than 90.0% |
DESCRIPTION |
White, odourless, granular powder |
FUNCTIONAL USES |
Antibrowning agent, antioxidant, preservative |
CHARACTERISTICS |
|
IDENTIFICATION |
|
Solubility (FNP 5) |
Freely soluble in water; slightly soluble in ethanol |
Test for potassium (FNP 5) |
Passes test |
Test for sulfite (FNP 5) |
Passes test |
PURITY |
|
Alkalinity |
Between 0.25 and 0.45% as K2CO3 |
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 accurately about 0.75 g of the sample and dissolve in a mixture of 100 ml of 0.1 N iodine and 5 ml of dilute hydrochloric acid TS. 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 7.912 mg of K2SO3. |