Magnesium Oxide Capsules
Magnesium Oxide Capsules contain NLT 90.0% and NMT 110.0% of the labeled amount of magnesium oxide (MgO).
• A. Identification TestsGeneral, Magnesium 191
Sample solution: Transfer the contents of 1 Capsule to a beaker. Add 10 mL of 3 N hydrochloric acid and 5 drops of methyl red TS, and heat to boiling. Add 6 N ammonium hydroxide until the color of the solution changes to deep yellow, then continue boiling for 2 min, and filter. Use the filtrate.
Acceptance criteria: Meet the requirements
Eriochrome black indicator solution: Dissolve 200 mg of eriochrome black T in a mixture of 15 mL of triethanolamine and 5 mL of dehydrated alcohol.
Sample solution: Mix the contents of NLT 20 Capsules. Transfer a portion of the powder, equivalent to 500 mg of magnesium oxide, to a beaker. Add 20 mL of water, and slowly add 40 mL of 3 N hydrochloric acid with mixing. Heat the mixture to boiling, cool, and filter into a 200-mL volumetric flask. Wash the beaker with water, adding the washings to the filter. Add water to volume.
Analysis: Transfer 20.0 mL of the Sample solution to a 400-mL beaker. Add 180 mL of water and 20 mL of triethanolamine, and stir. Add 10 mL of ammoniaammonium chloride buffer TS and 3 drops of Eriochrome black indicator solution. Cool the solution to 34 by immersion of the beaker in an ice bath. Remove, and titrate with 0.05 M edetate disodium VS to a blue endpoint. Perform a blank determination, substituting 20 mL of water for the Sample solution, and make any necessary correction (see Titrimetry 541). Each mL of 0.05 M edetate disodium consumed is equivalent to 2.015 mg of MgO.
Acceptance criteria: 90.0%110.0%
• Dissolution 711
Medium: 0.1 N hydrochloric acid; 900 mL
Apparatus 1: 100 rpm
Time: 45 min
Analysis: Using atomic absorption spectrophotometry at a wavelength of 285.2 nm, determine the amount of MgO dissolved, using filtered portions of the solution under test, suitably diluted with Medium if necessary, in comparison with a standard solution having a known concentration of magnesium in the same Medium.
Tolerances: NLT 75% (Q) of the labeled amount of MgO is dissolved.
• Uniformity of Dosage Units 905: Meet the requirements
• Acid-Neutralizing Capacity 301: NLT 5 mEq of acid is consumed by the minimum single dose recommended in the labeling, and NLT 85.0% of the expected mEq value calculated from the results of the Assay is obtained. Each mg of MgO has an expected acid-neutralizing capacity value of 0.0492 mEq.
• Packaging and Storage: Preserve in well-closed containers.
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USP35NF30 Page 3752