After injection of a sample directly in MS single quadropole the ''baseline'' of MSD signal up-sifted (approximately to 4000000 Abu). Why and what do you recommend me to do in order to fix this problem and return the baseline back to zero?
Is it possible too much sample was injected (concentration too high) and the cone and other parts need cleaning?
Is it possible too much sample was injected (concentration too high) and the cone and other parts need cleaning?
What masses are detected?
It could be a lekage, M/z 32 and 28 would then be the main masses even when the valve for the tuning substance is opened.
If m/z 207 etc. are main masses the stationary phase is bleeding out. Propably due to air break in.
Hi Ioanna.
I agree with Jack, i don't know if your quadrupole mass spectrometer is coupled with gc or lc, but high base line is possible which ionization source is dirty. I think cleaning up some times and the base line will return at the normal level. The unity for your spectrum intensity in your mass spectrometer isn't absorbance (Abs) , in some machine is count or relative intensity.
hope I helped you.
Thank you for your answers very much!
Mr.Silver, the concentration of the sample was a bit high...
Mr. Steola, the mass spectrometer is coupled with an lc, but when I ran the sample, it went directly through the mass detector and not the lc (no column was connected on the lc anyway).
Do you have any suggestions on cleaning methods (e.g.solvents) and other parts of the mass detector I should clean? I use isopropanol/water 50/50 for cleaning.
Mr.Neumann, I haven't checked what masses are detected, but I am going to.
Ionna.
I think is better you use methanol, water and formic acid for clean your ionization source, each mass spectrometer supplier has a different protocol for clean up. if you have used ESI source you can start with formic acid in water at 0,01% and after methanol. Is better you dismount the ionization source and use a ultrasonic bath.
Hi Ioanna!
Was there a slow increasing or an abrupt rise in the signal intensity?
You might also have to clean the pre rods or quadrupole itself. Did you use injection woth a syringe? Didsolved salts can cause higher current Flow in ESI resulting in higher signal.
In my opinion, it was due to the contamination of ion source and other parts...Direct injection into MS is sometimes very danger. It has to be carefully tried after considering boiling point and amount of the sample. Once it was contaminated, i would like to check the MS ions..If this happened by hydrocarbons? First increse the the temperature of ion source and quadrupole..and check...If it is possible for the baseline to be decreased, additional Ion source cleaning and HED cleaning can be the good choice to solve that problem in a short time..
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