shift level of baseline in SIM mod

[minhtruc]

Hello all,
I meet a problem during SIM mode in GC/MS: when the MSD swiches between groups of ions, the baseline changes in level, it is normal with small change, but here you see, it change so much. Has anyone met this situation? Please help me to solve this.

[Kostas Petritis]

Some ions can be more noisy than others (due to impurities eluted continuesly or other factors). The changes will be propotional to the sum of noise that you would observe for each ion if you would do a full scan at the same conditions...

[minhtruc]

Thank Kostas Petritis,
From your idea, I removed some ions (which is less important) in the group and the problem solved.