Packaging and storage—
Preserve in well-closed containers.
Identification—
A filtered solution of Tablets, equivalent to magnesium gluconate solution (1 in 10), diluted with water where necessary, responds to the
Identification tests under
Magnesium Gluconate.
Dissolution 
711
—
Medium:
water; 900 mL.
Apparatus 2:
50 rpm.
Time:
30 minutes.
Procedure—
Determine the amount of C12H22MgO14 dissolved, employing atomic absorption spectrophotometry at a wavelength of about 285.2 nm, in filtered portions of the solution under test, suitably diluted with water, in comparison with a Standard solution having a known concentration of magnesium in the same Medium.
Tolerances—
Not less than 80% (Q) of the labeled amount of C12H22MgO14 is dissolved in 30 minutes.
Assay—
Weigh and finely powder not fewer than 20 Tablets. Weigh accurately a portion of the powder, equivalent to about 800 mg of magnesium gluconate, 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 minutes, and filter, rinsing the filter with several portions of water. Dilute the combined filtrate and washings with water to about 150 mL. 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 20.73 mg of magnesium gluconate (C
12H
22MgO
14).
