Check the Turbomolecular Pump
Diagnostics will report the turbomolecular pump speed.
Make sure the pump speed reading is 100
±
2%.
•
If it is not, inspect cooling fans for proper operation.
Check the RF Adjustment
Check whether an RF adjustment is needed (particularly after you have changed
the ion trap temperature).
Check the Parameter Settings
Check whether you have set inappropriate method parameters.
•
Make sure that the ionization storage level permits storage in the trap of
the ions selected in the scan range.
If the spectrum returns, note which parameter(s) were causing the problem. If no
spectrum is present, and the trap was recently disassembled, the assembly of
the trap must be checked.
Check Ion Trap Assembly
1. Check whether you have incorrectly assembled the trap components.
2. Check whether there is a problem with the electron multiplier.
Loss of High Mass Peaks
The loss of high mass peaks may be due to:
•
RF ramp needs adjustment
•
Too many low mass ions (for example, air or water leak)
•
Improper method parameters
•
High trap temperatures may cause loss of high mass Cal Gas peaks
1. Check for an air leak.
2. Check RF ramp adjustment.
3. Reduce trap temperature to 150
°
C.
4. Enter Method Builder, check method parameters.
Part of the Spectrum is Missing
If you do not observe high- or low-mass ions in manual control but the ions in the
mid-range of the spectrum appear normal, you should investigate the following
possibilities:
•
An RF adjustment may be required, particularly if you have just changed
the ion trap temperature.
•
The ionization RF storage level may be incompatible with the scan
range.
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Summary of Contents for 4000 GC
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