Packaging and storage—
Preserve in well-closed containers.
Identification—
A solution (1 in 10) responds to the tests for
Potassium 
191
and for
Bicarbonate 191.
Loss on drying 731—
Dry it over silica gel for 4 hours: it loses not more than 0.3% of its weight.
Normal carbonate—
Grind 3.0 g of Potassium Bicarbonate with 25 mL of alcohol and 5 mL of water in a porcelain mortar. Add 3 drops of phenolphthalein TS, and titrate slowly with barium chloride solution, prepared by dissolving 12.216 g of barium chloride in 300 mL of water and diluting with alcohol to obtain 1000 mL of solution, until the suspension becomes colorless. Continue the grinding for 2 minutes, and if the color turns pink, continue the titration with the barium chloride solution to a colorless end-point. Repeat the grinding for 2 minutes and the addition of the barium chloride solution, if necessary, until the suspension is colorless after 2 minutes of grinding. Each mL of the barium chloride solution is equivalent to 6.911 mg of K2CO3: not more than 2.5% is found.
Heavy metals, Method I 231—
To 2 g add 5 mL of water and 8 mL of 3 N hydrochloric acid, heat to boiling, and maintain that temperature for 1 minute. Add 1 drop of phenolphthalein TS and sufficient 6 N ammonium hydroxide, dropwise, to give the solution a faint pink color. Cool, add 2 mL of 1 N acetic acid, and then dilute with water to 25 mL: the limit is 0.001%.
Organic volatile impurities, Method IV 467:
meets the requirements.
Assay—
Dissolve about 4 g of Potassium Bicarbonate, accurately weighed, in 100 mL of water, add methyl red TS, and titrate with 1 N hydrochloric 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 mL of 1 N hydrochloric acid is equivalent to 100.1 mg of KHCO3.
