Potassium Hydroxide
KOH
56.11
Potassium hydroxide.
Potassium hydroxide [1310-58-3].
»Potassium Hydroxide contains not less than 85.0percent of total alkali,calculated as KOH,including not more than 3.5percent of K2CO3.
Caution—Exercise great care in handling Potassium Hydroxide,as it rapidly destroys tissues.
Packaging and storage—
Preserve in tight containers.
Identification—
Asolution (1in 25)responds to the tests for Potassium á191ñ.
Insoluble substances—
Dissolve 1g in 20mLof water:the solution is complete,clear,and colorless.
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 Potassium Hydroxide,accurately weighed,in 40mLof carbon dioxide-free water.Cool the solution to 15
,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,then add methyl orange TS,and continue the titration to a persistent pink color.Each mLof 1Nsulfuric acid is equivalent to 56.11mg of total alkali,calculated as KOH,and each mLof acid consumed in the titration with methyl orange is equivalent to 138.2mg of K2CO3.
,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,then add methyl orange TS,and continue the titration to a persistent pink color.Each mLof 1Nsulfuric acid is equivalent to 56.11mg of total alkali,calculated as KOH,and each mLof acid consumed in the titration with methyl orange is equivalent to 138.2mg of K2CO3.
Auxiliary Information—
Staff Liaison:Karen A Russo,Ph.D.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 3065
Phone Number:1-301-816-8379