Carbonic acid, monoammonium salt, mixt. with ammonium carbamate.
Monoammonium carbonate mixture with ammonium carbamate [8000-73-5].

Packaging and storage— Preserve in tight, light-resistant containers, at a temperature not above 30.

Identification— When heated, it is volatilized without charring, and the vapor is alkaline to moistened litmus paper. A solution (1 in 20) effervesces with acids.

Residue on ignition 281: not more than 0.1%.

Chloride 221— A 2.0-g portion shows no more chloride than corresponds to 0.10 mL of 0.020 N hydrochloric acid (0.0035%).

Sulfate 221— A 2.0-g portion shows no more sulfate than corresponds to 0.10 mL of 0.020 N sulfuric acid (0.005%).

Heavy metals, Method I 231— Reduce to a coarse powder and volatilize 2 g of it on a steam bath. Add to the residue 1 mL of 3 N hydrochloric acid, and evaporate to dryness. Dissolve the residue in 2 mL of 1 N acetic acid, and add water to make 25 mL: the limit is 0.001%.

Assay— Place in a weighing bottle about 10 mL of water, tare the bottle and its contents, add about 2 g of Ammonium Carbonate, and weigh accurately. Transfer the contents of the bottle to a 250-mL flask, add 50.0 mL of 1 N sulfuric acid VS, and, when solution has been effected, add methyl orange TS, and titrate the excess acid with 1 N sodium hydroxide VS. Perform a blank determination (see Residual Titrations under Titrimetry 541). Each mL of 1 N sulfuric acid is equivalent to 17.03 mg of NH3.

Topic/Question	Contact	Expert Committee
Monograph	Robert H. Lafaver, B.A. Scientist 1-301-816-8335	(EM105) Excipient Monographs 1

USP32–NF27 Page 1165