Zinc Sulfate Tablets
DEFINITION
Zinc Sulfate Tablets contain NLT 95.0% and NMT 105.0% of the labeled amount of zinc sulfate monohydrate (ZnSO4·H2O). It may contain one or more suitable flavors and sweeteners.
IDENTIFICATION
• A. Sulfate
Sample solution:
Dissolve a portion of powdered Tablets in water to obtain a solution containing 50 mg/mL of zinc sulfate.
Hydrochloric acid solution:
Dilute 20 g of hydrochloric acid with water to 100 mL.
Barium chloride solution:
61 mg/mL of barium chloride
Analysis:
To 5 mL of the Sample solution add 1 mL of Hydrochloric acid solution and 1 mL of Barium chloride solution.
Acceptance criteria:
A white precipitate is formed.
• B. Zinc
Sample solution:
Proceed as directed in Identification test A.
Sodium hydroxide solution:
42 mg/mL of sodium hydroxide
Ammonium chloride solution:
107 mg/mL of ammonium chloride
Glycerin solution:
A mixture of glycerin and water (85:15)
Sodium sulfide solution:
Dissolve 12 g of sodium sulfide with heating in a 45-mL mixture of Glycerin solution and water (29:10), allow to cool, and dilute with the same mixture of solvents to 100 mL. The solution should be colorless.
Analysis:
To 5 mL of the Sample solution add 0.2 mL of Sodium hydroxide solution.
Acceptance criteria:
A white precipitate is formed. When an additional 2 mL of Sodium hydroxide solution is added, the precipitate dissolves. When 10 mL of Ammonium chloride solution is added, the solution remains clear. When 0.1 mL of Sodium sulfide solution is added, a white precipitate is formed.
ASSAY
• Procedure
Sample:
Portion of the powder, equivalent to 90 mg of zinc (about 247 mg of zinc sulfate monohydrate), from NLT 20 finely powdered Tablets
Blank:
Proceed as directed in the Analysis without the Sample.
Titrimetric system
(See Titrimetry 
541
.)
541.)
Mode:
Direct titration
Titrant:
0.1 M edetate disodium VS
Endpoint detection:
Visual
Analysis:
Transfer the Sample to a 200-mL volumetric flask. Dissolve in 15 mL of dilute acetic acid, and sonicate for 15 min. Dilute with water to volume, and mix. Add 50 mg of xylenol orange triturate to the solution, and mix. Neutralize the solution with 2 g of methenamine until the solution is a violet-pink color. Titrate with Titrant until the solution is yellow. Perform a Blank determination.
Calculate the percentage of the labeled amount of zinc sulfate monohydrate (ZnSO4·H2O) in the Sample taken:
Result = {[(VS 
VB) × M × F]/W} × 100
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 taken (mg) |
Acceptance criteria:
95.0%–105.0%
PERFORMANCE TESTS
• Uniformity of Dosage Units 905:
Meet the requirements
905:
Meet the requirements
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers, and store at controlled room temperature.
• Labeling:
Label the Tablets 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 |
| 701 |
Margareth R.C. Marques, Ph.D.
Senior Scientific Liaison 1-301-816-8106 |
(GCDF2010) General Chapters - Dosage Forms |
USP35–NF30 Page 5077
Pharmacopeial Forum: Volume No. 31(1) Page 82