Packaging and storage—
Preserve in tight containers.
Labeling—
Label the Tablets in terms of ferrous fumarate (C4H2FeO4) and in terms of elemental iron.
Identification—
To a portion of powdered Tablets, equivalent to 1 g of ferrous fumarate, add 25 mL of dilute hydrochloric acid (1 in 2), mix, and add 25 mL of water. Boil the solution for a few minutes, cool, and filter: the filtrate responds to the tests for
Iron 
191
.
Dissolution 711—
Medium:
0.1 N hydrochloric acid in 0.5% sodium lauryl sulfate; 900 mL.
Apparatus 2:
75 rpm.
Time:
45 minutes.
Procedure—
Determine the amount of C4H2FeO4 dissolved, employing atomic absorption spectrophotometry at a wavelength of about 248.3 nm on filtered portions of the solution under test, suitably diluted with Dissolution Medium if necessary, in comparison with a Standard solution having a known concentration of iron in the same Medium.
Tolerances—
Not less than 75% (Q) of the labeled amount of C4H2FeO4 is dissolved in 45 minutes.
Assay—
Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 500 mg of ferrous fumarate, to a 250-mL beaker. Add 25 mL of water, 25 mL of nitric acid, and 7.5 mL of perchloric acid. Cover with a ribbed watch glass, and heat to the production of strong fumes. Cool, rinse the watch glass and the sides of the beaker with water, and evaporate in a hood to near-dryness. Wash down the watch glass and the sides of the beaker with 2 mL of hydrochloric acid and then with a small volume of water. Warm slightly, if necessary, to dissolve the residue. Transfer to a glass-stoppered, 250-mL conical flask. Repeat the washing with 2 mL of hydrochloric acid, and complete the transfer to the flask, using not more than 20 to 25 mL of water for the transfer. Add 4 g of potassium iodide to the flask, insert the stopper, and allow to stand in the dark for 5 minutes. Add 75 mL of water, and titrate with 0.1 N sodium thiosulfate VS, adding 3 mL of
starch TS as the endpoint is approached. Each mL of 0.1 N sodium thiosulfate is equivalent to 16.99 mg of ferrous fumarate (C
4H
2FeO
4).
