Sulfinpyrazone
C23H20N2O3S 404.48
3,5-Pyrazolidinedione, 1,2-diphenyl-4-[2-(phenylsulfinyl) ethyl]-;
1,2-Diphenyl-4-[2-(phenylsulfinyl) ethyl]-3,5-pyrazolidinedione
[57-96-5].
(sul'' fin pir' a zone).
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C23H20N2O3S 404.48
3,5-Pyrazolidinedione, 1,2-diphenyl-4-[2-(phenylsulfinyl) ethyl]-;
1,2-Diphenyl-4-[2-(phenylsulfinyl) ethyl]-3,5-pyrazolidinedione
[57-96-5].DEFINITION
Sulfinpyrazone contains NLT 98.5% and NMT 101.5% of C23H20N2O3S, calculated on the dried basis.
IDENTIFICATION
• B.
The retention time of the major peak from the Sample solution corresponds to that from the Standard solution, as obtained in the test for Organic Impurities.
ASSAY
• Procedure
Sample:
600 mg of Sulfinpyrazone
Analysis:
Dissolve the Sample in 50 mL of neutralized alcohol, with slight heating. Add phenolphthalein TS. Titrate with 0.1 N sodium hydroxide VS. Each mL of 0.1 N sodium hydroxide is equivalent to 40.45 mg of C23H20N2O3S.
Acceptance criteria:
98.5%–101.5% on the dried basis
IMPURITIES
Organic Impurities
• Procedure
Solution A:
Acetonitrile and tetrahydrofuran (4:1)
Mobile phase:
Solution A and dilute phosphoric acid (3 in 1000) (7:13)
Solution B:
0.1 N acetic acid, 0.1 N potassium hydroxide, and water (6:5:14). Adjust to a pH of 5.0.
Diluent:
Acetonitrile and Solution B (4:1)
Standard solution:
10 µg/mL of USP Sulfinpyrazone RS in Diluent
Sample solution:
2 mg/mL of Sulfinpyrazone in Diluent
Chromatographic system
Mode:
LC
Detector:
UV 235 nm
Column:
4.6-mm × 10-cm; packing L1
Flow rate:
3 mL/min
Injection size:
10 µL
System suitability
Sample:
Standard solution
[Note—The retention time for sulfinpyrazone is about 4.0–4.6 min. ]
Suitability requirements
Tailing factor:
NMT 2.0
Relative standard deviation:
NMT 2.0%
Analysis
Samples:
Standard solution and Sample solution
Separately inject equal volumes (about 10 µL) of the Standard solution and the Sample solution into the chromatograph, record the chromatograms, and measure the responses of the major peaks.
Acceptance criteria:
The sum of the peak responses, other than that of the sulfinpyrazone peak, from the Sample solution is NMT four times the sulfinpyrazone peak response from the Standard solution (2.0%), and no single peak response is greater than twice the sulfinpyrazone peak response from the Standard solution (1.0%).
SPECIFIC TESTS
• Loss on Drying 
731
:
Dry a sample at 105
for 2 h: it loses NMT 0.5% of its weight.
731:
Dry a sample at 105 for 2 h: it loses NMT 0.5% of its weight.
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers.
• USP Reference Standards 11
11
USP Sulfinpyrazone RS 
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Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Leonel M. Santos, Ph.D.
Senior Scientific Liaison 1-301-816-8168 |
(SM12010) Monographs - Small Molecules 1 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 4724
Pharmacopeial Forum: Volume No. 35(3) Page 577