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Help Needed Resolving a Wavy Baseline on a 1260 Quaternary System

Question asked by agilentdallas on Jul 31, 2020
Latest reply on Oct 3, 2020 by agilentdallas

We are having baseline problems with two 1260 systems.  Both systems have quaternary pumps (G711B) with VWD (G7114A) detectors.  At a detection wavelength 254 nm with the pump flowing at 1 mL/min 90% A (H2O) and 10% B (acetonitrile), there is considerable waviness in the baseline.  I am using a restriction capillary to eliminate any column effects.  The height of the peaks is around 0.03 mAU.  If I switch to 100% channel A the waves are not observed and the peak-to-peak noise is about 0.005 mAU.


By contrast, if I perform the same separation on one of my 1100s, the waviness is not observed, and the peak-to-peak noise is about 0.015 mAU. 


What is causing this problem and how do I resolve it?


Examples are in the attached file.



 hplc 1260 baseline issues 1260 infinity quaternary lc system