Zinc Gluconate (zink gloo' koe nate). DEFINITION Zinc Gluconate contains NLT 97.0% and NMT 102.0% of zinc gluconate (C12H22O14Zn), calculated on the anhydrous basis. IDENTIFICATION • A. Identification TestsGeneral, Zinc 191: A 100-mg/mL solution meets the requirements. • B. Thin-Layer Chromatography Standard solution: 10 mg/mL of USP Potassium Gluconate RS Sample solution: 10 mg/mL of Zinc Gluconate, heating in a water bath at 60, if necessary, to dissolve Chromatographic system Mode: TLC Adsorbent: 0.25-mm layer of chromatographic silica gel Application volume: 5 µL Developing solvent system: Alcohol, ethyl acetate, ammonium hydroxide, and water (50:10:10:30) Spray reagent: Dissolve 2.5 g of ammonium molybdate in 50 mL of 2 N sulfuric acid in a 100-mL volumetric flask, add 1.0 g of ceric sulfate, swirl to dissolve, and dilute with 2 N sulfuric acid to volume. Analysis Samples: Standard solution and Sample solution Develop the chromatogram until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the chamber, and dry at 110 for 20 min. Allow to cool, and spray with the Spray reagent. Heat the plate at 110 for about 10 min. Acceptance criteria: The principal spot of the Sample solution corresponds in color, size, and RF value to that of the Standard solution. ASSAY • Procedure Sample: 700 mg of Zinc Gluconate Blank: 100 mL of water Titrimetric system (See Titrimetry 541.) Mode: Direct titration Titrant: 0.05 M edetate disodium VS Endpoint detection: Visual Analysis: Dissolve the Sample in 100 mL of water. Add 5 mL of ammoniaammonium chloride buffer TS and 0.1 mL of eriochrome black TS. Titrate with Titrant until the solution is deep blue in color. Perform a Blank determination. Calculate the percentage of zinc gluconate (C12H22O14Zn) in the Sample taken: Result = {[(VS VB) × M × F]/W} × 100
Acceptance criteria: 97.0%102.0% on the anhydrous basis IMPURITIES • Chloride and Sulfate, Chloride 221 Standard solution: 0.7 mL of 0.020 N hydrochloric acid Sample: 1.0 g Acceptance criteria: NMT 0.05% • Chloride and Sulfate, Sulfate 221 Standard solution: 1.0 mL of 0.020 N sulfuric acid Sample: 2.0 g Acceptance criteria: NMT 0.05% • Limit of Lead [NoteFor the preparation of all aqueous solutions and for the rinsing of glassware before use, use water that has been passed through a strong-acid, strong-base, mixed-bed ion-exchange resin. Select all reagents to have as low a content of lead as practicable, and store all reagent solutions in containers of borosilicate glass. Cleanse glassware before use by soaking in warm 8 N nitric acid for 30 min and by rinsing with deionized water. ] Ascorbic acidsodium iodide solution: 100 mg/mL of ascorbic acid and 192.5 mg/mL of sodium iodide Trioctylphosphine oxide solution: 50 mg/mL of trioctylphosphine oxide in 4-methyl-2-pentanone. [CautionThis solution causes irritation. Avoid contact with eyes, skin, and clothing. Take special precautions in disposing of unused portions of solutions to which this reagent is added. ] Standard solution: Transfer 5.0 mL of Lead Nitrate Stock Solution, prepared as directed in Heavy Metals 231, to a 100-mL volumetric flask, and dilute with water to volume. Transfer 2.0 mL of the resulting solution to a 50-mL volumetric flask, and add 10 mL of 9 N hydrochloric acid and 10 mL of water. Add 20 mL of Ascorbic acidsodium iodide solution and 5.0 mL of Trioctylphosphine oxide solution. Shake for 30 s, and allow to separate. Add water to bring the organic solvent layer into the neck of the flask, shake again, and allow to separate. The organic layer is the Standard solution, and it contains 2 µg/mL of lead. Sample solution: To a 50-mL volumetric flask add 1.0 g of Zinc Gluconate, 10 mL of 9 N hydrochloric acid, 10 mL of water, 20 mL of Ascorbic acidsodium iodide solution, and 5.0 mL of Trioctylphosphine oxide solution. Shake for 30 s, and allow to separate. Add water to bring the organic solvent layer into the neck of the flask, shake again, and allow to separate. The organic layer is the Sample solution. Blank: To a 50-mL volumetric flask add 10 mL of 9 N hydrochloric acid, 10 mL of water, 20 mL of Ascorbic acidsodium iodide solution, and 5.0 mL of Trioctylphosphine oxide solution. Shake for 30 s, and allow to separate. Add water to bring the organic solvent layer into the neck of the flask, shake again, and allow to separate. The organic layer is the Blank, and it contains 0 µg/mL of lead. Instrumental conditions Mode: Atomic absorption spectrophotometry Analytical wavelength: 283.3 nm Lamp: Lead hollow-cathode Flame: Airacetylene System suitability Samples: Standard solution and Blank Suitability requirements: The absorbance of the Standard solution and the absorbance of the Blank are significantly different. Analysis Samples: Standard solution, Sample solution, and Blank Concomittantly determine the absorbances of the Blank, Standard solution, and the Sample solution. Use the Blank to set the instrument to zero. Acceptance criteria: NMT 10 ppm: the absorbance of the Sample solution does not exceed that of the Standard solution. • Limit of Cadmium Standard stock solution: 0.1372 mg/mL of cadmium nitrate Standard solution: Pipet 25 mL of the Standard stock solution into a 100-mL volumetric flask, add 1 mL of hydrochloric acid, dilute with water to volume, and mix. It contains 12.5 µg/mL of cadmium (Cd). Sample stock solution: Transfer 10.0 g of Zinc Gluconate into a 50-mL volumetric flask, and dissolve in and dilute with water to volume. Sample solution A: Transfer 5.0 mL of the Sample stock solution to a 25-mL volumetric flask, and dilute with water to volume. This solution contains 0 µg/mL of added cadmium from the Standard solution. Sample solution B: Transfer 5.0 mL of the Sample stock solution to a 25-mL volumetric flask, add 2.0 mL of the Standard solution, and dilute with water to volume. This solution contains 1.0 µg/mL of added cadmium from the Standard solution. Sample solution C: Transfer 5.0 mL of the Sample stock solution to a 25-mL volumetric flask, add 4.0 mL of the Standard solution, and dilute with water to volume. This solution contains 2.0 µg/mL of added cadmium from the Standard solution. Blank: Water Instrumental conditions Mode: Atomic absorption spectrophotometry Analytical wavelength: 228.8 nm Lamp: Cadmium hollow-cathode Flame: Airacetylene Analysis Samples: Sample solution A, Sample solution B, and Sample solution C Determine the absorbances. Correct the absorbance values of Sample solution A, Sample solution B, and Sample solution C from that of the Blank. Plot the corrected absorbances of Sample solution A, Sample solution B, and Sample solution C versus their added cadmium concentrations, in µg/mL. Draw the straight line best fitting the three points, and extrapolate the line until it intercepts the concentration axis. From the intercept, determine the amount, in µg/mL, of cadmium in Sample solution A. Calculate the content of cadmium in the portion of Zinc Gluconate taken: Result = (C × V)/W
Acceptance criteria: NMT 5 ppm • Reducing Substances Sample: 1.0 g of Zinc Gluconate Blank: 10 mL of water Titrimetric system (See Titrimetry 541.) Mode: Residual titration Titrant 0.1 N iodine VS Back titrant: 0.1 N sodium thiosulfate VS Endpoint detection: Visual Analysis: Transfer the Sample to a 250-mL conical flask, dissolve in 10 mL of water, and add 25 mL of alkaline cupric citrate TS. Cover the flask, boil gently for 5 min, accurately timed, and cool rapidly to room temperature. Add 25 mL of 0.6 N acetic acid, 10.0 mL of Titrant, and 10 mL of 3 N hydrochloric acid, and titrate with Back titrant, adding 3 mL of starch TS as the endpoint is approached. Perform the Blank determination. Calculate the percentage of reducing substances (as dextrose) in the Sample taken: Result = {[(VB VS) × N × F]/W} × 100
Acceptance criteria: NMT 1.0% SPECIFIC TESTS • Water Determination, Method Ib 921: NMT 11.6% ADDITIONAL REQUIREMENTS • Packaging and Storage: Preserve in well-closed containers. Auxiliary Information Please check for your question in the FAQs before contacting USP.
USP35NF30 Page 5070 Pharmacopeial Forum: Volume No. 29(3) Page 683Chromatographic Column Chromatographic columns text is not derived from, and not part of, USP 35 or NF 30. |