Potassium Hydroxide Solution Content Potassium Hydroxide Solution contains 95－120% of the labeled content of potassium hydroxide (KOH=56.11). Description Potassium Hydroxide Solution is a colorless or slightly colored liquid. Identification (1) Potassium Hydroxide Solution in water (1 → 50) is strongly alkaline. (2) Potassium Hydroxide Solution responds to all tests for Potassium Salt as described in the Qualitative Tests. Purity (1) Clarity and color of solution Colorless, almost clear. Test Solution To Potassium Hydroxide Solution, add freshly boiled and cooled water to prepare 20% w/v solution of KOH, calculated from the labeled content, and use this solution as the sample solution. Measure 5 ml of the sample solution, mix with 20 ml of water. (2) Potassium Carbonate Not more than 2.0% as K2CO3 per KOH. Proceed as directed under Purity (2) for Potassium Hydropxide. (3) Heavy metals Not more than 30 µg/g as Pb per KOH. Proceed as directed under Purity (3) for Potassium Hydropxide. (4) Lead Not more than 10 µg/g as Pb per KOH. Proceed as directed under Purity (4) for Potassium Hydropxide. (5) Mercury Not more than 0.10 µg/g as Hg per KOH. Proceed as directed under Purity (5) for Potassium Hydropxide. (6) Arsenic Not more than 4.0 µg/g as As2O3 per KOH. Proceed as directed under Purity (6) for Potassium Hydropxide. Assay Weigh accurately the amount of Potassium Hydroxide Solution equivalent to about 5 g of potassium hydroxide (KOH). Add freshly boiled and cooled water to make 100 ml, and use this solution as the sample solution. Measure exactly 25 ml of the sample solution, and proceed as directed under the Assay for Potassium