Sodium Borate
Na2B4O7·10H2O 381.37

Borax.
Borax [1303-96-4].

Anhydrous 201.22 [1330-43-4].
»Sodium Borate contains an amount of Na2B4O7equivalent to not less than 99.0percent and not more than 105.0percent of Na2B4O7·10H2O.
Packaging and storage— Preserve in tight containers.
Identification— Asolution (1in 20)responds to the tests for Sodium á191ñand for Borate á191ñ.
Carbonate and bicarbonate— To 5mLof a solution (1in 20),contained in a test tube,add 1mLof 3Nhydrochloric acid:no effervescence is observed.
Heavy metals á231ñ— Dissolve 1g in 16mLof water and 6mLof 1Nhydrochloric acid,and dilute with water to 25mL:the limit is 0.002%.
Assay— Dissolve about 3g of Sodium Borate,accurately weighed,in 50mLof water,add methyl red TS,and titrate with 0.5Nhydrochloric acid VS.[NOTE—Heating on a steam bath may be required initially to effect solution.]Each mLof 0.5Nhydrochloric acid is equivalent to 95.34mg of Na2B4O7·10H2O.
Auxiliary Information— Staff Liaison:Catherine Sheehan,B.Sc.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 3075
Phone Number:1-301-816-8262