Tretinoin Gel
DEFINITION
Tretinoin Gel contains NLT 90.0% and NMT 130.0% of the labeled amount of C20H28O2.
IDENTIFICATION
• The retention time of the major peak in the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.
ASSAY
• Procedure
[Note—Avoid exposure to strong light, and use low-actinic glassware in the performance of the following procedure. ]
Mobile phase:
Prepare a mixture of acetonitrile and water (17:3). Add 5 mL of glacial acetic acid to each L of the mixture, mix well, filter, and degas.
Standard solution:
0.02 mg/mL of USP Tretinoin RS in methanol. [Note—Sonicate if needed. ]
Sample solution:
Transfer Tretinoin Gel, equivalent to 2 mg of tretinoin, to a 100-mL volumetric flask. Add about 70 mL of methanol, sonicate with intermittent shaking for 30 min, and dilute with methanol to volume. Centrifuge a portion of this solution at 3000 rpm for 10 min. Use the clear supernatant.
Chromatographic system
Mode:
LC
Detector:
UV 353 nm
Column:
4.6-mm × 15-cm; 5-µm packing L1
Flow rate:
1.5 mL/min
Injection size:
20 µL
Autosampler temperature:
15
System suitability
Sample:
Standard solution
Suitability requirements
Relative standard deviation:
NMT 2.0%
Tailing factor:
NMT 2.0
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of C20H28O2 in the portion of Gel taken:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = peak response from the Sample solution |
| rS | = | = peak response from the Standard solution |
| CS | = | = concentration of USP Tretinoin RS in the Standard solution (mg/mL) |
| CU | = | = nominal concentration of tretinoin in the Sample solution (mg/mL) |
Acceptance criteria:
90.0%–130.0%
PERFORMANCE TESTS
• Minimum Fill 
755
:
Meets the requirements
755:
Meets the requirements
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight containers, protected from light.
• USP Reference Standards 11
11
USP Tretinoin RS
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Feiwen Mao, M.S.
Senior Scientific Liaison 1-301-816-8320 |
(SM32010) Monographs - Small Molecules 3 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 4921
Pharmacopeial Forum: Volume No. 34(6) Page 1485