Packaging and storage—
Preserve in tight containers.
Identification—
Asolution (1in 25)responds to the tests for
Sodium á191ñ.
Insoluble substances and organic matter—
Asolution (1in 20)is complete,clear,and colorless to slightly colored.
Potassium—
Acidify 5mLof a solution (1in 20)with 6Nacetic acid,then add 5drops of sodium cobaltinitrite TS:no precipitate is formed.
Heavy metals á231ñ—
Dissolve 0.67g in a mixture of 5mLof water and 7mLof 3Nhydrochloric acid.Heat to boiling,cool,and dilute with water to 25mL:the limit is 0.003%.
Assay—
Dissolve about 1.5g of Sodium Hydroxide,accurately weighed,in about 40mLof carbon dioxide-free water.Cool the solution to room temperature,add phenolphthalein TS,and titrate with 1Nsulfuric acid VS.At the discharge of the pink color of the indicator,record the volume of acid solution required,add methyl orange TS,and continue the titration until a persistent pink color is produced.Each mLof 1Nsulfuric acid is equivalent to 40.00mg of total alkali,calculated as NaOH,and each mLof acid consumed in the titration with methyl orange is equivalent to 106.0mg of Na2CO3.