Ferrous Sulfate Syrup

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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DEFINITION

Ferrous Sulfate Syrup contains, in each 100 mL, NLT 3.75 g and NMT 4.25 g of ferrous sulfate heptahydrate (FeSO₄ · 7H₂O), equivalent to NLT 0.75 g and NMT 0.85 g of elemental iron.

Ferrous Sulfate Syrup is prepared as follows.

Dissolve the Ferrous Sulfate, Citric Acid, Peppermint Spirit, and 200 g of Sucrose in 450 mL of Purified Water, and filter the solution until clear. Dissolve the remainder of the Sucrose in the clear filtrate, and add Purified Water to make 1000 mL. Mix, and filter if necessary, through a pledget of cotton.

1 IDENTIFICATION

A. Identification Tests—General, Iron, Ferrous Salts〈191〉 and Sulfate〈191〉

Sample solution: Dilute 1 mL of Syrup with water to 100 mL.

Acceptance criteria: Meets the requirements

2 ASSAY

Procedure

Sample: 25 mL of Syrup

Blank: Proceed as in the Analysis without the Sample.

Titrimetric system

(See Titrimetry 〈541〉.)

Mode: Direct titration

Titrant: 0.1 N ceric sulfate VS

Indicator: Orthophenanthroline TS

Endpoint detection: Visual

Analysis: Add 15 mL of 2 N sulfuric acid and 100 mL of water to the Sample, and shake well. Add 3 drops of orthophenanthroline TS, and titrate with Titrant until the color changes. Perform a blank determination.

Calculate the amount of ferrous sulfate heptahydrate (FeSO₄ · 7H₂O) in g per each 100 mL of Syrup:

Result = {[(V_S − V_B ) × N × F]/W} × 100

V_S = Titrant volume consumed by the Sample (mL)

V_B = Titrant volume consumed by the Blank (mL)

N = actual normality of the Titrant (mEq/mL)

F = equivalency factor, 0.278 g/mEq

W = volume of Ferrous Sulfate Syrup for the Sample taken (mL)

Acceptance criteria: 3.75–4.25 g in each 100 mL

3 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers.

Labeling: Label the Syrup in terms of the content of ferrous sulfate heptahydrate (FeSO₄ · 7H₂O) and in terms of the content of elemental iron.