Zinc Sulfate Oral Solution

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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1 DEFINITION

Zinc Sulfate Oral Solution contains NLT 90.0% and NMT 110.0% of the labeled amount of zinc sulfate monohydrate (ZnSO₄ · H₂O). It may contain one or more suitable flavors and sweeteners.

2 IDENTIFICATION

Identification Tests - General, Zinc 〈191〉 and Sulfate 〈191〉: Meets the requirements

3 ASSAY

Procedure

Sample: An accurately measured volume of Oral Solution, equivalent to 99 mg of zinc sulfate monohydrate (ZnSO₄ · H₂O)

Blank: 60 mL of water and 10 mL of ammonia–ammonium chloride buffer TS. Add 0.1 mL of eriochrome black TS.

Titrimetric system

(See Titrimetry 〈541〉.)

Mode: Direct titration

Titrant: 0.05 M edetate disodium VS

Endpoint detection: Visual

Analysis: Transfer the Sample to a 250-mL flask. Add 50 mL of water and 10 mL of ammonia–ammonium chloride buffer TS and 0.3 mL of eriochrome black TS. Titrate with Titrant to a green endpoint.

Calculate the percentage of the labeled amount of zinc sulfate monohydrate (ZnSO₄ · H₂O) in the portion of Oral Solution taken:

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

V_S = Titrant volume consumed by the Sample (mL)

V_B = Titrant volume consumed by the Blank (mL)

M = actual molarity of the Titrant (mM/mL)

F = equivalency factor, 179.46 mg/mM

W = nominal amount of zinc sulfate monohydrate in the Sample (mg)

Acceptance criteria: 90.0%–110.0%

4 SPECIFIC TESTS

Specific Gravity 〈841〉: 1.18–1.24

pH 〈791〉: 2.5–4.5

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers, and store in a cool, dry place protected from light.

Labeling: Label the Oral Solution in terms of zinc sulfate monohydrate (ZnSO · H O) and in terms of elemental zinc.