Magnesium Chloride
MgCl2·6H2O 203.30

Magnesium chloride,hexahydrate
Magnesium chloride hexahydrate [7791-18-6].

Anhydrous 95.21 [7786-30-3].
»Magnesium Chloride contains not less than 98.0percent and not more than 101.0percent of MgCl2·6H2O.
Packaging and storage— Preserve in tight containers.
Labeling— Where Magnesium Chloride is intended for use in hemodialysis,it is so labeled.
Identification— Asolution (1in 20)responds to the tests for Magnesium á191ñand for Chloride á191ñ.
pHá791ñ: between 4.5and 7.0,in a 1in 20solution in carbon dioxide-free water.
Insoluble matter— Dissolve 20g,accurately weighed,in 200mLof water,heat to boiling,and digest in a covered beaker on a steam bath for 1hour.Filter through a tared filtering crucible,wash thoroughly,and dry at 115:the weight of the residue does not exceed 1mg (0.005%).
Sulfate á221ñ— A10-g portion shows no more sulfate than corresponds to 0.50mLof 0.020Nsulfuric acid (0.005%).
Barium— Dissolve 1g in 10mLof water,and add 1mLof 2Nsulfuric acid:no turbidity is produced within 2hours.
Limit of calcium—
Dilute hydrochloric acid ,Lanthanum solution,Standard preparations,and Blank solution—Proceed as directed in the test for Limit of calciumunder Magnesium Carbonate.
Test preparation— Transfer 10.0g of Magnesium Chloride to a 200-mLvolumetric flask,add water to dissolve it,add 4mLof Lanthanum solution,dilute with water to volume,and mix.
Procedure— Proceed as directed for Procedurein the test for Limit of calciumunder Magnesium Carbonate.Calculate the percentage of calcium in the Magnesium Chloride taken by multiplying the concentration,in µg per mL,of calcium found in the Test preparationby 0.002:the limit is 0.01%.
Potassium— Dissolve 5g in 5mLof water,and add 0.2mLof sodium bitartrate TS:no turbidity is produced within 5minutes.
Aluminum á206ñ(where it is labeled as intended for use in hemodialysis)— Proceed as directed using 2.0g of Magnesium Chloride to prepare the Test Preparation:the limit is 1µg per g.
Heavy metals á231ñ— Dissolve 2g in water to make 25mL:the limit is 0.001%.
Organic volatile impurities,Method Iá467ñ: meets the requirements.
Assay— Weigh accurately about 450mg of Magnesium Chloride,dissolve in 25mLof 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 0.05Mdisodium edetate is equivalent to 10.17mg of MgCl2·6H2O.
Auxiliary Information— Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(PA4)Pharmaceutical Analysis 4
USP28–NF23Page 1168
Pharmacopeial Forum:Volume No.30(3)Page 893
Phone Number:1-301-816-8251
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