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Sodium Borate
Na2B4O7·10H2O 381.37

Borax [1303-96-4].

Anhydrous 201.22 [1330-43-4].
» Sodium Borate contains an amount of Na2B4O7 equivalent to not less than 99.0 percent and not more than 105.0 percent of Na2B4O7·10H2O.
Packaging and storage— Preserve in tight containers.
Identification— A solution (1 in 20) responds to the tests for Sodium 191 and for Borate 191.
Carbonate and bicarbonate— To 5 mL of a solution (1 in 20), contained in a test tube, add 1 mL of 3 N hydrochloric acid: no effervescence is observed.
Heavy metals 231 Dissolve 1 g in 16 mL of water and 6 mL of 1 N hydrochloric acid, and dilute with water to 25 mL: the limit is 0.002%.
Residual solvents 467: meets the requirements.
(Official January 1, 2007)
Assay— Dissolve about 3 g of Sodium Borate, accurately weighed, in 50 mL of water, add methyl red TS, and titrate with 0.5 N hydrochloric acid VS. [NOTE—Heating on a steam bath may be required initially to effect solution.] Each mL of 0.5 N hydrochloric acid is equivalent to 95.34 mg of Na2B4O7·10H2O.
Auxiliary Information— Staff Liaison : Catherine Sheehan, B.Sc., Scientist
Expert Committee : (EM105) Excipient Monographs 1
USP29–NF24 Page 3421
Phone Number : 1-301-816-8262