Ciclic Baseline in HPLC

Dear Support,

We are facing a problem in our HPLC systems related to a cyclical baseline oscillation for different methods, different equipment (at least 9 HPLC) connected to different UPS, in different rooms. The oscillation is more critical in the last 2 week and we are having problems to release analysis. (see attachments)

In 2019 we had the same problem that lasted a few months and then stabilized. We could not find the cause at the time

We are investigating the cause of this problem and we would like you expertise to support us to solve this problem.

The electrical department are evaluating the electrical network and we are also investigating if something in our water my have caused this problem since we had high TOC levels in our milli-q some weeks ago and now we are using WFI for the analysis as contingence plan.

We asked our Water's support about the difference in WFI conductivity for the detector and according to him, for this kind of optical system there is no relation, but it is possible that the high TOC may have caused some problem in the optical part of the equipment. We are doing some tests to check this hypothesis changing the flow cell of the equipment.

Have you had any experience with this type of case? What can cause this type of cyclical oscillation in several systems in the same period? Do you think the points we are evaluating make sense? Do you recommend us any point to investigate or any tests that we can do?
This problem is impacting our release and we need help to resolve it as soon as possible.

Thank you in advance!

Best Regards 



  • Hi Tallis,  Can you give me a bit more information?  What instrument are you seeing this on (especially the detector model) and details on the method (MP, Flow Rate, Purge/prime that may have been done)?

    In the mean time, here is a link to the KB that might be helpful.  I included Alliance systems because your mentioned HPLC, but most of the solutions will apply to any HPLC.