Sodium Hydroxide
NaOH 40.00
Sodium hydroxide
[1310-73-2].
(soe' dee um hye drox' ide).
NaOH 40.00
Sodium hydroxide
[1310-73-2].DEFINITION
Sodium Hydroxide contains NLT 95.0% and NMT 100.5% of total alkali, calculated as sodium hydroxide (NaOH), including NMT 3.0% of sodium carbonate (Na2CO3).
[Caution—Exercise great care in handling sodium hydroxide, because it rapidly destroys tissues.
]
IDENTIFICATION
• A. Identification Tests—General, Sodium 
191
:
A solution (1 in 25) meets the requirements.
191:
A solution (1 in 25) meets the requirements.
ASSAY
• Procedure
Sample solution:
1.5 g of Sodium Hydroxide in 40 mL of carbon dioxide-free water. Cool the solution to room temperature.
Blank:
40.0 mL of carbon dioxide-free water
Titrimetric system
(See Titrimetry 541.)
541.)
Mode:
Direct titration
Titrant:
1 N sulfuric acid
Endpoint detection:
Visual
Analysis:
To the Sample, add phenolphthalein TS. Titrate with 1 N sulfuric acid VS. At the discharge of the pink color of the indicator, record the volume of Titrant (VS1). Add methyl orange TS, and continue the titration until a persistent pink color is produced. Record the volume of Titrant (VS2). Perform a blank determination, and make any necessary corrections.
Calculate the percentage of total alkali, calculated as sodium hydroxide (NaOH), in the Sample taken:
Result = {[(VS1 
VB) × N × F1]/W} × 100
VB) × N × F1]/W} × 100| VS1 | = | = volume of Titrant consumed by the Sample to the first endpoint (mL) |
| VB | = | = volume of Titrant consumed by the Blank (mL) |
| N | = | = actual normality of the Titrant (mEq/mL) |
| F1 | = | = equivalency factor, 40.00 (mg/mEq) |
| W | = | = weight of the Sample (mg) |
Calculate the percentage of sodium carbonate (Na2CO3) in the Sample taken:
Result = {[(VS2 VS1) × N × F2]/W} × 100
VS1) × N × F2]/W} × 100| VS2 | = | = volume of Titrant consumed by the Sample to the second endpoint (mL) |
| VS1 | = | = volume of Titrant consumed by the Sample to the first endpoint (mL) |
| N | = | = actual normality of the Titrant (mEq/mL) |
| F2 | = | = equivalency factor, 106.0 (mg/mEq) |
| W | = | = weight of the Sample (mg) |
Acceptance criteria:
95.0%–100.5% of total alkali; NMT 3.0% of sodium carbonate (Na2CO3)
IMPURITIES
• Potassium
Sample solution:
1 in 20
Analysis:
Acidify 5 mL of the Sample solution with 6 N acetic acid, then add 5 drops of sodium cobaltinitrite TS.
Acceptance criteria:
No precipitate is formed.
• Heavy Metals 231
231
Test preparation:
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.
Analysis:
Proceed as directed in the chapter.
Acceptance criteria:
NMT 30 ppm
SPECIFIC TESTS
• Insoluble Substances and Organic Matter:
A solution (1 in 20) is complete, clear, and colorless to slightly colored.
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 1955