Thermo Scientific ISQ, User Manual

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3
Tuning the ISQ
Tuning the ISQ Mass Spectrometer
26 ISQ User Guide Thermo Scientific
• EI Full Tune —This tune is used to completely retune the system. It takes the longest
amount of time to run, but the advantage of using it is that it re-optimizes nearly all the
parameters affecting the signal. This type of tune will perform a mass calibration, tune the
lenses and resolution, and perform a leak check. The detector gain will be calibrated to
generate 300,000 electrons for every ion that strikes the detector. You should run an EI
full tune when the daily tune or the daily tune check is not adequate, when the electron
multiplier is getting old (tuning to high electron multiplier voltages), or the first tune
after you replace the electron multiplier. Unless your SOP requires it, this is not the best
tune to use on a daily basis because of the length of time it takes to run it.
• CI- Tune —This tune is used to analyze samples with negative CI. The standard NCI
tune performs a mass calibration, then tunes the lenses and sets the resolution. This type
of tune assumes you are using methane as the CI reagent gas and tunes the system with a
1.0 mL/min flow. This tune does not set the detector gain.
• CI+ Tune —This tune is used to analyze samples with positive CI. The standard PCI tune
performs a mass calibration, then tunes the lenses and sets the resolution. This type of
tune assumes you are using methane as the CI reagent gas and tunes the system with a
1.5 mL/min flow. This tune does not set the detector gain.
2. Select the Display Report When Complete checkbox so that you can view the tune
report after running the tune.
Note Chemical ionization tunes are very different from the electron ionization tunes. You
should not use a CI tune unless your instrument has a CI ion volume and CI reagent gas
installed.
Note If the instrument was last used in EI mode and tuned with a high repeller voltage
before switching to a clean CI ion Source, a tune file with a low repeller voltage should be
loaded in manual tune and saved to the instrument before tuning in CI mode.
Tip If you intend to use ammonia reagent gas, attach methane to one CI reagent gas port
and ammonia to the other port. Tune the instrument using methane, then switch to the
ammonia port. Allow plenty of time for the new reagent gas to purge the CI tubing before
starting your analysis.
Note To add a tune type to the list, see Modifying an Automatic Tune .