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- Posts: 656
- Joined: Tue Jul 05, 2005 7:45 am
- Location: Denmark
Have you ever experienced this before? I switched from JT Baker to VWR Acetonitrile Gradient Grade and two peaks changed place! This is a HILIC method that is very sensitive to pH so I assume that the pH is different in the two acetonitriles.
The pH in the mobile phase is controlled by a 10 mM ammonium acetate pH 4.5. I cannot measure the pH in the mobile phase (75% acetonitrile), but it appears as the JT Baker is more acidic than VWR.