Improved Gradient Method with Faster Equilibration

The USP Assay Method for Valsartan in combination with Hydrochlorothiazide features a 27 minute gradient with a 13 minute re-equilibration for a total run time of 40 minutes. In this method, the run time was a quarter of the USP method, and the Column equilibrates much faster when gradients are used. This demonstrates a substantial time and solvent savings for the analytical laboratory.

Five Chromatograms are overlaid below which shows the Robustness and Precision of this Method.


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2. Valsartan

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

Time (minutes) %B
0 10
8 90
9 10

Post Time: 1 minute
Injection vol.: 10μL
Flow rate: 1.0ml  / minute
Detection: UV @ 265nm
Sample Preparation:
Stock Solution: A Diovan® HCT brand tablet containing 160mg Valsartan and 25 mg Hydrochlorothiazide was ground and added to a 50 mL volumetric flask. The flask was diluted to mark with 50:50 Solvent A / Solvent B mixture and sonicated. A portion was then filtered with a 0.45μm Nylon Syringe Filter AQ™ Brand (MicroSolv Tech Corp.).
Working Solution: 100μL of the stock solution was diluted with 900μL of a 50:50 Solvent A / Solvent B mixture.
t0: 1 minute

Comparison of This Method and the USP Method
Bidentate C18 Ordinary C18
Total Run Time 10 Minutes 40 Minutes
Column Volume Equilibration 1 Column 10 Columns
Solvent Usage per Run 10ml 40ml

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