Zinc Gluconate Tablets
DEFINITION
Zinc Gluconate Tablets contain NLT 93.0% and NMT 107.0% of the labeled amount of Zn, in the form of zinc gluconate (C12H22O14Zn).
IDENTIFICATION
• A. Thin-Layer Chromatography
Standard solution:
USP Potassium Gluconate RS in water; 10 mg/mL
Sample solution:
Transfer a weighed quantity of powdered Tablets to a suitable flask, and add the necessary volume of water to obtain a solution containing about 10 mg/mL of zinc gluconate. Shake and sonicate, heating in a water bath at 60
, if necessary, and filter.
, if necessary, and filter.
Chromatographic system
Mode:
TLC
Adsorbent:
0.25-mm layer of chromatographic silica gel
Application volume:
5 µL
Developing solvent system:
Alcohol, water, ammonium hydroxide, and ethyl acetate (50:30:10:10)
Spray reagent:
Dissolve 2.5 g of ammonium molybdate in about 50 mL of 2 N sulfuric acid in a 100-mL volumetric flask, add 1.0 g of ceric sulfate, swirl to dissolve, dilute with 2 N sulfuric acid to volume, and mix.
Analysis
Samples:
Standard solution and Sample solution
When the solvent front has moved about three-fourths the length of the plate, remove the plate from the chamber, and dry at 110 for 20 min. Allow to cool, spray with Spray reagent, and heat the plate at 110 for about 10 min.
for 20 min. Allow to cool, spray with Spray reagent, and heat the plate at 110 for about 10 min.
Acceptance criteria:
The principal spot from the Sample solution corresponds in color, size, and RF value to that from the Standard solution.
• B. Procedure
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.
Sample solution:
Shake and sonicate the amount of powdered Tablets with the necessary volume of water to obtain a solution containing 100 mg/mL of zinc gluconate. Heat in a water bath at 60, if necessary, and filter.
, if necessary, and filter.
Analysis:
To 5 mL of the Sample solution add 0.2 mL of Sodium hydroxide solution, add an additional 2 mL of Sodium hydroxide solution, and add 10 mL of Ammonium chloride solution. Add 0.1 mL of Sodium sulfide solution.
Acceptance criteria:
A white precipitate is formed after the first addition of Sodium hydroxide solution. The precipitate dissolves after the second addition of Sodium hydroxide solution. The solution remains clear after addition of Ammonium chloride solution, and a white precipitate forms after addition of Sodium sulfide solution.
STRENGTH
• Procedure
Sample solution:
Weigh and finely powder NLT 20 Tablets. Weigh a portion of the powder, equivalent to about 80 mg of zinc, transfer to a suitable crucible, and ignite, gently at first, until free from carbon. Cool the crucible, add 25 mL of water and 5 mL of hydrochloric acid, and stir. Heat on a steam bath for 5 min, and filter, rinsing the filter with several portions of water. Dilute the combined filtrate and washes with water to about 100 mL.
Analysis:
Add ammonia–ammonium chloride buffer TS until the solution is neutral to litmus. Add 5 mL of ammonia–ammonium chloride buffer TS and 0.1 mL of eriochrome black TS, and titrate with 0.05 M edetate disodium VS to a blue endpoint. Each mL of 0.05 M edetate disodium is equivalent to 3.27 mg of Zn or 22.78 mg of zinc gluconate (C12H22O14Zn).
Acceptance criteria:
93.0%–107.0%
PERFORMANCE TESTS
• Disintegration 
701
:
For Tablets intended to be mixed with water prior to intake as oral liquids
701:
For Tablets intended to be mixed with water prior to intake as oral liquids
Time:
NMT 60 s
• Disintegration and Dissolution of Dietary Supplements 2040:
For Tablets not to be mixed with water prior to ingestion
2040:
For Tablets not to be mixed with water prior to ingestion
Medium:
Hydrochloric acid 0.01 N; 900 mL
Apparatus 2:
50 rpm
Time:
45 min
Analysis:
Determine the amount of C12H22O14Zn dissolved, employing atomic absorption spectrophotometry at the resonance emission line for zinc, at 213.8 nm, on filtered portions of the solution under test, suitably diluted with water, in comparison with a standard solution having a known concentration of zinc in the same Medium.
Tolerances:
NLT 75% of the labeled amount of C12H22O14Zn is dissolved.
• Uniformity of Dosage Units 905:
Meet the requirements
905:
Meet the requirements
ADDITIONAL REQUIREMENTS
• Packaging and storage:
Preserve in tight containers, protected from light.
• Labeling:
Label the Tablets in terms of elemental zinc, and also in terms of zinc gluconate (C12H22O14Zn).
The labeling indicates whether the Tablets are intended to be mixed with water before intake.
• USP Reference Standards 11
11
USP Potassium Gluconate RS 
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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 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 5072
Pharmacopeial Forum: Volume No. 35(3) Page 597