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help! MS1 signal drop in QE MS

Posted: Mon Sep 21, 2015 6:44 pm
by cavaliersun2003
I recently got a problem with my Q exective MS, the MS1 signal suddenly droped from 10E9 to 10E7, although background signal also droped, and the spectra looks normal too. The MS2 looked good too with 10E7 signal. I searched the data, and still gives me lots of proteins IDs. I switched from nanospray to regular HESI sourse, and the signal is still low. Does anyone here have a clue about this problem?
thank you!


Posted: Tue Sep 22, 2015 1:54 am
by gadsouza
Do you normally clean your ion transfer tube? If it is dirty and starting to clog, you will experience a drop of signal. Otherwise it could be dirty front optics even if your endurance test is giving good results.

Easier thing to test would be replacing the used tube for a new one and see what happens.

Posted: Tue Sep 22, 2015 4:10 am
by Rolando

I would also check the and clean the S-lens behind the transfer tube.