Hi,

Are you doing infusion or running the samples through a LC system?

Hi Farid,

from the moment we started to see this problem  we also noticed instability of the signal (doing calibration) both running the calibrant doing infusion from theh syringe  and just A/B solution (whatwever %) from LC. Running samples from LC they are, until this evening, like that in the picture. No matter what we tried... 

Did you check if the capillary is clogged?

Sorry Farid, I didn't get what you mean.  Do you mean the metal needle...or what? We changed already the probe, the metal needle inside and in both cases nothing seemed to be helpfull for our problem. Whatever sample we run it looks like the one in the picture.

Thank you Jeremy and Farid!

Jeremy, unfortunately I do not remember right now but it might happened that some parameter has been changed in our tune by mistake...!I'll chack it!  

Now I'm courius about what do you mean referring to positive/negative switch. Do you mean just that swiching from positive to negative mode, can cause this kind of TIC signal? Why?

Hello everybody,

we checked what suggested and it seems that everything is as expected to be by default settings. We asked intervention of a specialist. Let's see ... 

Hi, 

My guess is that the problem is on the fluidic path side.

I suspect you have a leak somewhere. The pattern you showed is pretty much typical for leaking systems. The signal drops because of air bubbles and unstable flow.

Can you take a picture of the source? I can help you figure out the problem.

Hello everybody.

Thank you for your answers and suggestions.

We are still running some test but it looks like the specialist has found a problem on nitrogen line connected with C-trap and Orbitrap. 

For updating informations I'll go through what we did with the help of the specialist. It might help...

@Tom,

we replaced s-lens and metal needle from the probe at the time we started to have this problem and it didn't solve it. About electron multiplier the specialist said that they looked like "noisy" for some reason. But all the parameters we considered (about lens and other voltages) were almost the same as in those experiments the Orbitrap worked properly. 

@Fabrizio,

I agree with your suspect and it was what we tested just after testing the probe and the first part of the Orbitrap. It looked like it was working properly. We were facing signal instability even from the syringe using calibrant solution. and our Orbitrad was not even passing calibrations.  

Again, thank you for your help. 

Giuseppe

What is the dominant mass of that peak ?

Just do restart the electronic switch and this problem will be gone.