New specifications prepared at the 53rd JECFA (1999) and published in FNP 52 Add 7 (1999). PTMDI 0.8 mg/kg bw for iron, established at the 27th JECFA in 1983. | |
DEFINITION |
Ferrous sulfate, dried consists primarily of the monohydrate with smaller amounts of the tetrahydrate |
Chemical formula |
FeSO4 � H2O |
Formula weight |
Monohydrate: 169.91 |
Assay |
Not less than 86% and not more than 89% of FeSO4 |
DESCRIPTION |
A greyish-white to buff-coloured powder |
FUNCTIONAL USES |
Nutrient supplement |
CHARACTERISTICS |
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IDENTIFICATION |
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Solubility (FNP 5) |
Dissolves slowly in water; insoluble in ethanol |
Test for iron (FNP 5) |
Passes test |
Test for sulfate (FNP 5) |
Passes test |
PURITY |
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Acid-insoluble matter |
Not more than 0.05% |
Lead (FNP 5) |
Not more than 2 mg/kg |
Mercury |
Not more than 1 mg/kg |
TESTS |
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PURITY TESTS |
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Mercury |
Dithizone extraction solution Dilute dithizone solution Hydroxylamine hydrochloride solution Mercury stock solution Diluted standard mercury solution Sodium citrate solution Sample solution Procedure Work in subdued light. Prepare a control containing 3 ml of Diluted standard mercury solution, 30 ml of 1.7 N nitric acid, 5 ml of Sodium citrate solution and 1 ml of Hydroxylamine hydrochloride solution. Using a pH meter, adjust the pH of the control and the sample solution to 1.8 with ammonium hydroxide and transfer them to separators. Extract with two 5-ml portions of Dithizone extraction solution followed by 5 ml of chloroform. Discard the aqueous solutions. Transfer into clean separators the combined extracts of the two solutions, add 10 ml of dilute hydrochloric acid (1 in 2), shake well and discard the chloroform layers. Wash the acid solutions with 3 ml of chloroform and discard the chloroform layers. Add to each separator 0.1 ml of 0.05 M disodium EDTA and 2 ml of 6 N acetic acid, mix, and then slowly add 5 ml of ammonium hydroxide. Stopper the separators, and cool under a stream of cold water. Dry the outside of the separators. Through the tops of the separators, pour the solutions carefully to avoid losses, into separate beakers, and using pH meters, adjust their pH to 1.8 with 6 N ammonium hydroxide. Return the solutions to their original separators, add 5 ml of Diluted dithizone extraction solution and shake vigorously. Any colour developed in the Sample solution does not exceed that in the control. |
METHOD OF ASSAY |
Dissolve about 1 g of the sample, accurately weighed, in a mixture of 25 ml of 2 N sulfuric acid and 25 ml of recently boiled and cooled water, add orthophenanthroline TS, and immediately titrate with 0.1 N ceric sulfate. Perform a blank determination, and make any necessary correction. Each ml of 0.1 N ceric sulfate is equivalent to 27.80 mg of FeSO4�7H2O. |