ISQ User Guide - Write Frame of Mind

7 Optimizing Your Method
Modifying an Automatic Tune
• Initial Detector Gain—Select this option to set the true gain of the electron
multiplier. The gain is the number of electrons generated for every ion that strikes the
detector. This is typically set between 1 x10 5 and 3x10 5 electrons per ion. Gains
larger than this will generate more electrons per ion, but both the analyte ion and the
noise ion signals will be larger. The detectivity of the instrument will be the same.
You can also tune to lower gain values, which decreases the signal strength. Lower
values also increase the chance that an ion will not be detected. As the electron
multiplier ages, the voltage required for a given gain will increase. Depending on your
sample load and if your system is leak tight (oxygen is bad for the detector), you
should not have to perform this tune very often.
• Tune Detector—Select this checkbox to tune the detector.
• Adjust Detector Sensitivity—Select this checkbox to tune the detector to generate a
consistent area count of a calibration gas ion for the tune report. Because the intensity
of the cal gas varies depending on the atmospheric pressure and temperature of the
lab, this option will result in larger variation in the analytical runs.
– Mass—Use this pull-down menu to select the calibration gas mass you want to
use.
– Intensity—Use this field to enter the intensity you want to see on the tune
report.
12. Click the Diagnostics tab and select a test to confirm the operational ability of the ISQ.
Thermo Scientific ISQ User Guide 87