C12H22MgO14·xH2O(anhydrous) 414.60

D-Gluconic acid,magnesium salt (2:1),hydrate.
Magnesium D-gluconate (1:2)hydrate.
Magnesium D-gluconate (1:2)dihydrate 450.64 [59625-89-7].

Anhydrous [3632-91-5].

Packaging and storage— Preserve in well-closed containers.

USP Reference standards á11ñ— USP Potassium Gluconate RS.

Identification—

pHá791ñ: between 6.0and 7.8,in a solution (1in 20).

Water,Method Ib á921ñ: between 3.0%and 12.0%,30minutes being allowed for solubilization of the specimen and for the reaction to reach completion,and a blank determination being performed with the same volume of Reagentbut without the specimen.Calculate the water content of the specimen,in mg,taken by the formula: in which Xbis the volume,in mL,of standardized Water-Methanol Solutionrequired to neutralize the unconsumed Reagentin the blank determination;and the other terms are as defined therein.

Chloride á221ñ— A1.0-g portion shows no more chloride than corresponds to 0.70mLof 0.020Nhydrochloric acid (0.05%).

Sulfate á221ñ— A2.0-g portion shows no more sulfate than corresponds to 1.0mLof 0.020Nsulfuric acid (0.05%).

Heavy metals á231ñ— Dissolve 1.0g in 10mLof water,add 6mLof 3Nhydrochloric acid,and dilute with water to 25mL:the limit is 0.002%.

Reducing substances— Transfer 1.0g to a 250-mLconical flask,dissolve in 10mLof water,and add 25mLof alkaline cupric citrate TS.Cover the flask,boil gently for 5minutes,accurately timed,and cool rapidly to room temperature.Add 25mLof 0.6Nacetic acid,10.0mLof 0.1Niodine VS,and 10mLof 3Nhydrochloric acid,and titrate with 0.1Nsodium thiosulfate VS,adding 3mLof starch TSas the endpoint is approached.Perform a blank determination,omitting the specimen,and note the difference in volumes required.Each mLof the difference in volume of 0.1Nsodium thiosulfate consumed is equivalent to 2.7mg of reducing substances (as dextrose):the limit is 1.0%.

Organic volatile impurities,Method Iá467ñ: meets the requirements.

Assay— Weigh accurately about 800mg of Magnesium Gluconate,dissolve in 20mLof water,add 5mLof ammonia-ammonium chloride buffer TSand 0.1mLof eriochrome black TS,and titrate with 0.05Medetate disodium VSto a blue endpoint.Each mLof 0.05Medetate disodium is equivalent to 20.73mg of C12H22MgO14.

Expert Committee:(DSN)Dietary Supplements:Non-Botanicals

USP28–NF23Page 1170

Phone Number:1-301-816-8389