G4212B waves in baseline

We have seen some "waves" in the baseline of several G4212B detectors. We thought it was due to the power line, but we have taken many measures to avoid it (UPS, filters, mesh wires, etc.). Additionally we verified the same problem in another laboratory of the company (located in another place)
The curious thing is that they have an almost perfect sinusoidal shape, with a period of approximately 7 minutes.
I attach images of the chromatograms (even one corresponds to the reading at 360 nm, which rules out a solvent/pumping problem)

  • Have you looked at any of the other outputs from the detector?  You can view and collect some of the other temperature/voltage readbacks from the G4212B.  Maybe you will see the same pattern in one of those traces that may help with diagnosis.

    Out of interest, what's the mobile phase that you are using?  What is the source of and scale of the black signal in the second image?


  • Thanks for your answer!
    I'm going to try to read the voltage and temperature of the detector, to see if there is any relationship.
    Regarding the mobile phase, it is a phosphate buffer with acetonitrile, there is nothing strange about it.
    The image corresponds to the reading of an iso-plot at a high wavelength (our system takes a reading at a low wavelength, 230 nm, but since we acquired in a DAD, I wanted to see if it was something due to the solvent, which we have ruled out )

  • Have you done the lamp tests in Lab Advisor as well?  Do you see this with the flow off?

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