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.

1. Hydrochlorothiazide (HCT)
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)

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


No 150 Valsartan and Hydrochlorothiazide Analyzed with HPLC pdf  0.5 Mb   Download File