Methylpyrrolidone
C5H9NO 99.1
1-Methyl-2-pyrrolidinone;
N-Methyl-2-pyrrolidone;
N-Methylpyrrolidone;
1-Methyl-2-Pyrrolidone;
Pyrrolidin, 1-methyl-2-one-;
1-Methylpyrrolidin-2-one;
N-Methyl-
-butyrolactam;
N-Methyl tetrahydropyrrolone;
1-Methyl-2-oxopyrrolidine;
N-Methyl-1-oxotetramethyleneamine;
2-Methyl-2-azacyclopentanone
[872-50-4].
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C5H9NO 99.1
1-Methyl-2-pyrrolidinone;
N-Methyl-2-pyrrolidone;
N-Methylpyrrolidone;
1-Methyl-2-Pyrrolidone;
Pyrrolidin, 1-methyl-2-one-;
1-Methylpyrrolidin-2-one;
N-Methyl-
-butyrolactam;
N-Methyl tetrahydropyrrolone;
1-Methyl-2-oxopyrrolidine;
N-Methyl-1-oxotetramethyleneamine;
2-Methyl-2-azacyclopentanone
[872-50-4].IDENTIFICATION
IMPURITIES
Inorganic Impurities
• Heavy Metals 
231
:
NMT 10 ppm
231:
NMT 10 ppm
Organic Impurities
• Procedure
Standard solution:
To 1 mL of USP Methylpyrrolidone RS, add 1 mL of pyrrolidone, and dilute with methylene chloride to 20 mL.
Sample solution:
Methylpyrrolidone (neat)
Chromatographic system
Mode:
GC
Detector:
Flame ionization
Column:
0.32-mm × 30-m fused-silica capillary column, 5-µm layer of phase G2
Temperature
Injector:
280
Detector:
280
Column:
See the temperature program table below.
| Initial Temperature ( ) |
Temperature Ramp ( /min) |
Final Temperature ( ) |
Hold Time at Final Temperature (min) |
|---|---|---|---|
| 100 | — | 100 | 0 |
| 100 | 3 | 170 | 30 |
Carrier gas:
Nitrogen
Linear velocity:
20 cm/s
Split ratio:
100:1
Injection size:
1 µL
System suitability
Sample:
Standard solution
Suitability requirements
Resolution:
NLT 2.0 between pyrrolidone and methylpyrrolidone
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of each impurity, excluding any solvent peaks and peaks NMT 0.02%, in the portion of Methylpyrrolidone taken:
Result = (rU/rT) × 100
| rU | = | = peak response of each individual impurity from the Sample solution |
| rT | = | = sum of the responses of all the peaks from the Sample solution |
Acceptance criteria:
NMT 0.1% of any individual impurity; and NMT 0.3% of total impurities
SPECIFIC TESTS
• Alkalinity
Bromothymol blue solution:
Dissolve 50 mg of bromothymol blue in a mixture of 4 mL of 0.02 M sodium hydroxide and 20 mL of alcohol, and dilute with water to 100 mL.
Sample:
Methylpyrrolidone (neat)
Analysis:
Add 0.5 mL of Bromothymol blue solution as indicator to 50 mL of water, and adjust with 0.02 M potassium hydroxide or 0.02 M hydrochloric acid until a yellow color is obtained. Add 50 mL of the Sample. Titrate with 0.02 M hydrochloric acid to the initial coloration.
Acceptance criteria:
NMT 8.0 mL of 0.02 M hydrochloric acid is required.
• Clarity of Solution
[Note—The Sample is to be compared to the Reference suspension in diffused daylight 5 min after preparation of the Reference suspension. ]
Hydrazine solution:
10 mg/mL of hydrazine sulfate. [Note—Allow to stand 4–6 h before use. ]
Methenamine solution:
Transfer 2.5 g of methenamine to a 100-mL glass-stoppered flask, add 25.0 mL of water, insert the glass stopper, and mix to dissolve.
Primary opalescent suspension
[Note—This suspension is stable for 2 months, provided it is stored in a glass container free from surface defects. The suspension must not adhere to the glass and must be well mixed before use. ]
Transfer 25.0 mL of the Hydrazine solution to the Methenamine solution in the 100-mL glass-stoppered flask.
[Note—Allow to stand for 24 h. ]
Opalescence standard:
Transfer 15.0 mL of the Primary opalescent suspension to a 1000-mL volumetric flask, and dilute with water to volume. [Note—This suspension should not be used beyond 24 h after preparation. ]
Reference suspension:
Transfer 5.0 mL of the Opalescence standard to a 100-mL volumetric flask, and dilute with water to volume.
Sample:
Methylpyrrolidone (neat)
Analysis:
Transfer a sufficient portion of the Sample to a test tube of colorless, transparent, neutral glass with a flat base and an internal diameter of 15–25 mm to obtain a depth of 40 mm. Similarly transfer portions of the Reference suspension and water to separate matching test tubes. Compare the Sample, Reference suspension, and water in diffused daylight, viewing vertically against a black background (see Spectrophotometry and Light-Scattering 851, Visual Comparison). [Note—The diffusion of light must be such that the Reference suspension can readily be distinguished from water. ]
851, Visual Comparison). [Note—The diffusion of light must be such that the Reference suspension can readily be distinguished from water. ]
Acceptance criteria:
The Sample shows the same clarity as that of water, or its opalescence is not more pronounced than that of the Reference suspension.
• Color of Solution
Sample
Methylpyrrolidone (neat)
Analysis:
Transfer a sufficient portion of the Sample to a test tube of colorless, transparent, neutral glass with a flat base and an internal diameter of 15–25 mm, to obtain a depth of 40 mm. Similarly transfer a portion of water to a separate matching test tube. Compare the color of the Sample with that of water in diffused daylight, viewing vertically against a white background (see Spectrophotometry and Light-Scattering 851, Visual Comparison).
851, Visual Comparison).
Acceptance criteria:
The Sample has the color of water.
• Water, Method Ic 921:
NMT 0.1%, determined on 1.0 g
921:
NMT 0.1%, determined on 1.0 g
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in light-resistant containers.
• USP Reference Standards 11
11
USP Methylpyrrolidone RS
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 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 1869
Pharmacopeial Forum: Volume No. 35(5) Page 1205