Chromatography Forum

We are running an Orbitrap mass spectrometer with a Vanquish UHPLC on the front end and have encountered some baseline issues in ESI- mode. What ever is causing it appears to be affecting our method as our instrument precision is no where near where it was as of two months ago. The baseline has big waves with a frequency of about every 3 minutes, which makes me wonder if it is LC related. Anyone ever experience something like this before?

Thanks!

First you'll need to determine if it's the LC or the MS. Disconnect the LC and check the performance of the MS by infusing something you have experience with.

We do not have any issues calibrating the instrument, which requires an infusion of a solution

Not familiar with your hardware, but if you can tune the mass spec with no problem, try running a blank and do a scan of the background and see if you notice any masses that shouldn't be there. Sometimes solvents can be contaminated, or the glassware, etc.