FeSO4·7H2O 278.02

Sulfuric acid, iron(2+) salt (1:1), heptahydrate.
Iron(2+) sulfate (1:1) heptahydrate [7782-63-0].

Anhydrous 151.91 [7720-78-7].

Packaging and storage— Preserve in tight containers.

Labeling— Label it to indicate that it is not to be used if it is coated with brownish yellow basic ferric sulfate.

Identification— It responds to the tests for Ferrous Salts 191 and for Sulfate 191.

Arsenic, Method I 211— Transfer 1.0 g to a round-bottom, 100-mL flask fitted with a glass joint, add 40 mL of 9 N sulfuric acid and 2 mL of potassium bromide solution (3 in 10), and immediately connect the flask to a condenser having a matching glass joint and a reservoir with a water jacket that is cooled by ice-water. Heat the flask gently over a low flame until the solid dissolves, then distill until 25 mL of distillate collects in the reservoir. Transfer this distillate to the arsine generator flask, and wash the condenser and the reservoir with several small portions of water, adding the washings to the generator flask. Swirl to mix, add bromine TS until the color of the solution is slightly yellow, and dilute with water to 35 mL. The limit is 3 ppm.

Lead— Using Ferrous Sulfate, proceed as directed in the test for Lead under Ferrous Gluconate: the limit is 0.001%.

Mercury— It meets the requirements of the test for Mercury under Ferrous Fumarate.

Organic volatile impurities, Method IV 467: meets the requirements.

Residual solvents 467: meets the requirements.

Assay— Dissolve about 1 g of Ferrous Sulfate, accurately weighed, in a mixture of 25 mL of 2 N sulfuric acid and 25 mL of freshly boiled and cooled water. Add orthophenanthroline TS, and immediately titrate with 0.1 N ceric sulfate VS. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N ceric sulfate is equivalent to 15.19 mg of FeSO4 or to 27.80 mg of FeSO4·7H2O.

Expert Committee : (DSN05) Dietary Supplements - Non-Botanicals

USP29–NF24 Page 901

Phone Number : 1-301-816-8389