Chromatography Forum

It's been a while since I have visited this forum but in the past you folks have been very helpful and amazing so let's hope for more of the same!

I use an Esquire 3000+ quadrupole ion trap system. In the past couple of months I've seen baseline noise increasing at higher (>800) m/z. The noise increasing in intensity in a concave up shape with increasing m/z. The noise appears to be electronic as opposed to being generated from actual ions as it does not change with increasing/decreasing ion trap bath gas pressure, ion accumulation time, nor if isolating a particular m/z for MSn reactions (if I isolate the noise remains).
Related to this I have been having issues with the diagnostics on the trap reliably passing when tested, especially the tests where higher potential/currents are measured - and that leads me to believe the two are related.

If anyone on the forums has a clue I'd be happy to hear it, I've tried several things myself, replaced parts, and have come up with zip, so a new direction would be appreciated. Only, please don't suggest to talk to the manufacturer, I've tried but they don't have any more service contracts on the model so seem not to care, though they offered to sell me a new instrument to fix my issue

This is something typical on Esquire systems, we already have experienced it several times on ours.
It can happen if the ion trap is dirty. You can try to remove the lid hiding the ion trap and carefully flush the ion trap with pure nitrogen (you can use the nitrogen used for the nebulizer to do that). With a bit of luck, it will remove the impurities causing this exponential noise.

Sounds like a good suggestion to me. However, wouldn't the impurities varying in their intensity with changes in pressure? What I mean is with more He, wouldn't there be less X, therefore lower intensity of X? When varying the bath gas pressure, or removing it altogether, there is no change in the signal of this high mass contribution.
The only thing that affects intensity is the scan range and scan speed. I've attached an image to clarify what it is I am seeing.

https://drive.google.com/file/d/0B0EbY8 ... VMeEE/view

Looks like a dirty trap... As suggested try blowing it out but I have had similar issues where it turned out a trap was contaminated with oil via gas inlet...

That cost me a new trap...