Potassium Hydroxide
KOH 56.11
Potassium hydroxide
[1310-58-3].
(poe tas' ee um hye drox' ide).
KOH 56.11
Potassium hydroxide
[1310-58-3].DEFINITION
Potassium Hydroxide contains NLT 85.0% of total alkali, calculated as KOH, including NMT 3.5% of K2CO3.
[Caution—Exercise great care in handling Potassium Hydroxide, because it rapidly destroys tissues.
]
IDENTIFICATION
• A. Identification Tests—General, Potassium 
191
:
A solution (1 in 25) meets the requirements.
191:
A solution (1 in 25) meets the requirements.
ASSAY
• Procedure
Sample:
1.5 g of Potassium Hydroxide
Titrimetric system
(See Titrimetry 541.)
541.)
Mode:
Direct titration
Titrant:
1 N sulfuric acid VS
Endpoint detection:
Colorimetric
Analysis:
Dissolve the Sample in 40 mL of carbon dioxide-free water. Cool the solution to 15
, and add phenolphthalein TS. 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.
, and add phenolphthalein TS. 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.
Acceptance criteria:
NLT 85.0% of total alkali, calculated as KOH, including NMT 3.5% of K2CO3
IMPURITIES
• Heavy Metals 231
231
Test preparation:
0.67 g of Potassium Hydroxide 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.
Acceptance criteria:
NMT 30 ppm
SPECIFIC TESTS
• Insoluble Substances
Sample solution:
1 g of Potassium Hydroxide in 20 mL of water
Acceptance criteria:
The Sample solution is complete, clear, and colorless.
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight containers.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Robert H. Lafaver, M.S.
Scientific Liaison 1-301-816-8335 |
(EXC2010) Monographs - Excipients |
USP35–NF30 Page 1928