SODIUM HYDROGEN SULFITE

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. 222

DEFINITION

Chemical names

Sodium hydrogen sulfite, sodium bisulfite

C.A.S. number

7631-90-5

Chemical formula

NaHSO₃

Formula weight

104.06

Assay

Not less than 58.5% and not more than 67.4% of SO₂

DESCRIPTION

White crystals or granular powder having an odour of sulfur dioxide

FUNCTIONAL USES

Antibrowning agent, antioxidant, preservative

CHARACTERISTICS

IDENTIFICATION

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)

2.5 - 4.5 (1 in 10 soln)

Iron (FNP 5)

Not more than 10 mg/kg
Proceed as directed in the Limit Test using 0.5 ml of Iron Standard Solution (5 ľg Fe) in the control

Lead (FNP 5)

Not more than 2 mg/kg
Determine by atomic absorption spectroscopy (FNP 5)

Selenium

Not more than 5 mg/kg
See description under TESTS

TESTS

PURITY TESTS

Selenium

Reagents: Hydrochloric acid, hydrazinium sulfate, standard selenium solution (100 ľg Se/ml)

Procedure
Weigh 2.0 ą 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.
Into a second beaker, weigh 1.0 ą 0.1 g of sample, add 0.05 ml standard selenium solution and proceed as above.
To each beaker add 2 g hydrazinium sulfate and warm to dissolve. Let stand for 5 min. Dilute the contents of each beaker to 50 ml in a Nessler tube and compare the colour of the two solutions. The sample should be less pink than the sample with the added standard.

METHOD OF ASSAY

Weigh 0.2 g of the sample, to the nearest mg, add 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 3.203 mg of SO₂.

	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. 222
DEFINITION
Chemical names	Sodium hydrogen sulfite, sodium bisulfite
C.A.S. number	7631-90-5
Chemical formula	NaHSO₃
Formula weight	104.06
Assay	Not less than 58.5% and not more than 67.4% of SO₂
DESCRIPTION	White crystals or granular powder having an odour of sulfur dioxide
FUNCTIONAL USES	Antibrowning agent, antioxidant, preservative
CHARACTERISTICS
IDENTIFICATION
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)	2.5 - 4.5 (1 in 10 soln)
Iron (FNP 5)	Not more than 10 mg/kg Proceed as directed in the Limit Test using 0.5 ml of Iron Standard Solution (5 ľg Fe) in the control
Lead (FNP 5)	Not more than 2 mg/kg Determine by atomic absorption spectroscopy (FNP 5)
Selenium	Not more than 5 mg/kg See description under TESTS
TESTS
PURITY TESTS
Selenium	Reagents: Hydrochloric acid, hydrazinium sulfate, standard selenium solution (100 ľg Se/ml) Procedure Weigh 2.0 ą 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. Into a second beaker, weigh 1.0 ą 0.1 g of sample, add 0.05 ml standard selenium solution and proceed as above. To each beaker add 2 g hydrazinium sulfate and warm to dissolve. Let stand for 5 min. Dilute the contents of each beaker to 50 ml in a Nessler tube and compare the colour of the two solutions. The sample should be less pink than the sample with the added standard.
METHOD OF ASSAY	Weigh 0.2 g of the sample, to the nearest mg, add 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 3.203 mg of SO₂.