3
Tuning the ISQ
Tuning the ISQ Mass Spectrometer
Thermo Scientific
ISQ User Guide
25
Figure 20.
List of Available Tunes in ISQ Autotune
•
Daily Tune Check
—This tune check is used to check how well your last tune is
performing. It is the fastest tune type. The daily tune check performs a leak check, makes
sure the mass calibration is okay, and sets the detector sensitivity to generate a m/z 69 ion
with an intensity of 20,000,000 counts. If your SOP allows it, you can use this tune to
rapidly verify that the previous lens tune is still generating good spectra.
•
Daily Tune
—This tune is used to quickly tune the system. It performs a mass calibration
and leak check, tunes the lenses and resolution, and sets the detector sensitivity to
generate a m/z 69 ion with an intensity of 20,000,000 counts. You can perform a daily
tune as frequently as your SOP requires. If the system is tuning to your satisfaction, then
there is no need to perform the more time-consuming default or full tunes.
•
EI Default Tune
—This tune creates a default tune file. It requires a clean instrument,
starts with factory tune, and sets repeller to 0V and quadrupole voltage to a low value.
This tune is used to generate a base for all the other tunes. As a result, you should only use
this tune when the ion source is clean. The EI default tune will start with the tune file
stored in the instrument at the factory and then perform a mass calibration and leak
check, set the repeller to 0 V and tunes the lenses. The quadrupole offset voltage will be
set to a low value to improve resolution, which is also tuned. The detector gain will be
calibrated to generate ~ 300,000 electrons for every ion that strikes the detector. This
tune is used in cases where a dirty ion source has been replaced by a clean one or where
the computer has been replaced. Additionally, this tune will generate spectra that are the
closest in appearance to the factory tune.
Note
If you are starting with a clean source, this is the recommended tune to run.
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