H3BO3 61.83

Boric acid (H3BO3).
Boric acid (H3BO3) [10043-35-3].

Packaging and storage— Preserve in well-closed containers.

Labeling— Label the container with a warning that it is not for internal use.

Solubility in alcohol— One g dissolves completely in 10mLof boiling alcohol.

Completeness of solution— One g dissolves in 25mLof water,producing a clear solution.

Identification— It responds to the tests for Borate á191ñ.

Loss on drying á731ñ— Dry it over silica gel for 5hours:it loses not more than 0.5%of its weight.

Heavy metals,Method Iá231ñ— Dissolve 1g in 23mLof water,and add 2mLof 1Nacetic acid:the limit is 0.002%.

Assay— Dissolve about 2g of Boric Acid,accurately weighed,in 100mLof a mixture of equal volumes of glycerin and water,previously neutralized to phenolphthalein TS,and titrate with 1Nsodium hydroxide VS.Discharge the pink color by the addition of 50mLof glycerin,neutralized to phenolphthalein TS,and continue the titration until the pink color reappears.Each mLof 1Nsodium hydroxide is equivalent to 61.83mg of H3BO3.

Expert Committee:(EMC)Excipients:Monograph Content

USP28–NF23Page 2967

Phone Number:1-301-816-8262