Ammonium Phosphate
(NH4)2HPO4 132.06

Phosphoric acid,diammonium salt.
Diammonium phosphate [7783-28-0].
»Ammonium Phosphate contains not less than 96.0percent and not more than 102.0percent of (NH4)2HPO4.
Packaging and storage— Preserve in tight containers.
Identification— Asolution (1in 20)responds to the tests for Ammonium á191ñand for Phosphate á191ñ.
pHá791ñ: between 7.6and 8.2,in a solution (1in 100).
Chloride á221ñ— A1.0-g portion shows no more chloride than corresponds to 0.40mLof 0.020Nhydrochloric acid (0.03%).
Sulfate á221ñ— A0.20-g portion shows no more sulfate than corresponds to 0.30mLof 0.020Nsulfuric acid (0.15%).
Heavy metals á231ñ— Dissolve 2.0g in 25mLof water:the limit is 0.001%.
Assay— Dissolve about 600mg of Ammonium Phosphate,accurately weighed,in 40mLof water,and titrate with 0.1Nsulfuric acid VSto a pHof 4.6,determined potentiometrically.Each mLof 0.1Nsulfuric acid is equivalent to 13.21mg of (NH4)2HPO4.
Auxiliary Information— Staff Liaison:Catherine Sheehan,B.Sc.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 2956
Phone Number:1-301-816-8262