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3
CI Troubleshooting
Common CI-Specific Problems
Because of the added complexity of the parts required for CI, there are many
potential problems added. By far the greatest number and most serious
problems with CI are associated with leaks or contamination in the reagent gas
introduction system. NCI is especially sensitive to the presence of air; leaks small
enough to cause no problems in PCI can destroy NCI sensitivity.
As with EI, if the MS tunes well and no air leak is present, sample sensitivity
problems should be addressed by GC inlet maintenance first.
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Wrong reagent gas
Reagent gas not hooked up or hooked up to wrong reagent gas inlet port
Wrong ions entered in tune file
Wrong tune file selected
Not enough bakeout time has elapsed since vent (background is too high)
Wrong column positioning (extending > 4-5 mm past tip of interface)
Interface tip seal not installed
EI source installed in CI mode
EI filament or other EI source parts in CI ion source
Air leaks in reagent gas flow path
CI filament has stretched and sagged:
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High emission current
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High temperature
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Filament was defective
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Linear (no inflection point) electron energy (EIEnrgy) ramp
7250 Accurate-Mass Q-TOF Troubleshooting and Maintenance Manual
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Table of Contents
Troubleshooting
