An Assay Method for Etodolac Tablets

The USP Assay Method for  Etodolac tablets uses a Phosphoric Acid based Mobile Phase which is not LCMS compatible. The Method in this Application Note is more versatile since it can be used for HPLC or LCMS. The Gradient can be adjusted if lower Retention is required.

Data from two Column lots is shown to illustrate Method Robustness and Consistency.


Method Conditions
Column: Cogent Bidentate C18™, 4μm, 100Å
Catalog No.: 40018-75P
Dimensions: 4.6 x 75mm
Mobile Phase:
A: DI Water with 0.1% Formic Acid (v/v)
B: Acetonitrile with 0.1% Formic Acid (v/v)

Time (minutes) %B
0 10
1 10
6 80
7 10

Post Time: 3 minutes
Injection vol.: 1μL
Flow rate: 1.0mL / minute
Detection: UV @ 275nm
Sample Preparation: A portion of 50:50 Solvent A / Solvent B diluent was added and the flask was sonicated for 10 minutes. It was then diluted to mark and mixed. A portion was filtered with a 0.45μm Nylon Syringe Filter (MicroSolv Tech Corp.) and diluted 1:10.
t0: 0.9 minutes

Note: Etodolac is a prescription nonsteroidal anti-inflammatory drug. It is used for treatment of pain resulting from inflammation in conditions such as arthritis. It is sold in the USA under the trade name Lodine by Almirall Limited.


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