KHCO3 100.12

Carbonic acid,monopotassium salt.
Monopotassium carbonate [298-14-6].

Packaging and storage— Preserve in well-closed containers.

Identification— Asolution (1in 10)responds to the tests for Potassium á191ñand for Bicarbonate á191ñ.

Loss on drying á731ñ— Dry it over silica gel for 4hours:it loses not more than 0.3%of its weight.

Normal carbonate— Grind 3.0g of Potassium Bicarbonate with 25mLof alcohol and 5mLof water in a porcelain mortar.Add 3drops of phenolphthalein TS,and titrate slowly with barium chloride solution,prepared by dissolving 12.216g of barium chloride in 300mLof water and diluting with alcohol to obtain 1000mLof solution,until the suspension becomes colorless.Continue the grinding for 2minutes,and if the color turns pink,continue the titration with the barium chloride solution to a colorless end-point.Repeat the grinding for 2minutes and the addition of the barium chloride solution,if necessary,until the suspension is colorless after 2minutes of grinding.Each mLof the barium chloride solution is equivalent to 6.911mg of K2CO3:not more than 2.5%is found.

Heavy metals,Method Iá231ñ— To 2g add 5mLof water and 8mLof 3Nhydrochloric acid,heat to boiling,and maintain that temperature for 1minute.Add 1drop of phenolphthalein TSand sufficient 6Nammonium hydroxide,dropwise,to give the solution a faint pink color.Cool,add 2mLof 1Nacetic acid,and then dilute with water to 25mL:the limit is 0.001%.

Organic volatile impurities,Method IVá467ñ: meets the requirements.

Assay— Dissolve about 4g of Potassium Bicarbonate,accurately weighed,in 100mLof water,add methyl red TS,and titrate with 1Nhydrochloric acid VS.Add the acid slowly,with constant stirring,until the solution becomes faintly pink.Heat the solution to boiling,cool,and continue the titration until the pink color no longer fades after boiling.Each mLof 1Nhydrochloric acid is equivalent to 100.1mg of KHCO3.

Expert Committee:(PA1)Pharmaceutical Analysis 1

USP28–NF23Page 1581

Phone Number:1-301-816-8379