KOH 56.11

Potassium hydroxide.
Potassium hydroxide [1310-58-3].

Packaging and storage— Preserve in tight containers.

Identification— A solution (1 in 25) responds to the tests for Potassium 191.

Insoluble substances— Dissolve 1 g in 20 mL of water: the solution is complete, clear, and colorless.

Heavy metals 231— Dissolve 0.67 g in a mixture of 5 mL of water and 7 mL of 3 N hydrochloric acid. Heat to boiling, cool, and dilute with water to 25 mL: the limit is 0.003%.

Residual solvents 467: meets the requirements.

Assay— Dissolve about 1.5 g of Potassium Hydroxide, accurately weighed, in 40 mL of carbon dioxide-free water. Cool the solution to 15, add phenolphthalein TS, and titrate with 1 N sulfuric 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 mL of 1 N sulfuric acid is equivalent to 56.11 mg of total alkali, calculated as KOH, and each mL of acid consumed in the titration with methyl orange is equivalent to 138.2 mg of K2CO3.

Expert Committee : (EM105) Excipient Monographs 1

USP29–NF24 Page 3407

Phone Number : 1-301-816-8262