Zinc Sulfate Oral Solution
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.
IDENTIFICATION
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 
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 = {[(VS VB) × M × F]/W} × 100
VS== Titrant volume consumed by the Sample (mL)
VB== 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%
SPECIFIC TESTS
•  Specific Gravity 841: 1.18–1.24
•  pH 791: 2.5–4.5
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 (ZnSO4·H2O) and in terms of elemental zinc.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Natalia Davydova
Scientific Liaison
1-301-816-8328
(DS2010) Monographs - Dietary Supplements
USP35–NF30 Page 5077
Pharmacopeial Forum: Volume No. 31(2) Page 468