TSQ Vantage - background in negative mode.

Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.

6 posts Page 1 of 1
Hello all. In last time in negative mode appeared a huge background peak with 169 m/z. What can it be and how to remove it ? I've tried to clean ESi box, wash tubes but without effect.

Thanks!
Did you isolate it to the MS only?
Rndirk wrote:
Did you isolate it to the MS only?

In case calibration with polythyrosine (direct infusion in mass) or direct conection LC without column - the same strong 169 m/z.
What if you just turn on the MS without infusion or column flow?

If it's still there and it's bothering your analysis, i'd advice to take cleaning 1 step further and clean the part behind the transfer tube: the first lens system/ion funnel.

If you don't have experience doing that it's best to ask Thermo.
Rndirk wrote:
What if you just turn on the MS without infusion or column flow?

If it's still there and it's bothering your analysis...


I tried to do such way,but peak is still here (.
So i have to clean capillary and ion optics(we can do it without Thermo service).
Thank you so much!
Sorry for confusion. Ii checked out system one more time - contamination with 169 m/z goes from channel of pump with organic phase. Very strange thing - i got excellent tune with polythyrosine in positive and negative modes, but instrumental method in MRM doesn't work properly. MRM in negative - no signal. in positive -everything good.
6 posts Page 1 of 1

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