ISQ User Guide - Write Frame of Mind

3 Tuning the ISQ
Tuning the ISQ with Xcalibur
6. Select the tune type you want to use:
• Daily Tune Check—This tune 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 tune 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has been replaced by a clean one or where the computer has been replaced.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.
• EI Full Tune—This tune is used to completely retune the system. It takes the longest
amount of time to run, but its advantage 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.
26 ISQ User Guide Thermo Scientific