5 Operating in CI Mode
To Perform an NCI Autotune (Methane Reagent Gas)
5977C GC/MSD Operating Manual 133
To Perform an NCI Autotune (Methane
Reagent Gas)
Procedure
1 From the Tune and Vacuum Control view, load NCICH4.U (or an existing tune
file for the reagent gas you are using).
2 From the Setup menu, select the CI Tune Wizard and follow the system
prompts.
Accept the default temperature and other settings.
If you use an existing tune file, be sure to save it with a new name if you
don’t want to overwrite the existing values.
3 Under the Tune menu, click CI Autotune.
There are no tune performance criteria. If autotune completes, it passes. (See
Figure 44 on page 134.) If the tune sets the EMV at or above 2,600 V, however,
you may not be able to acquire data successfully if your method sets EMV to
“+400” or higher.
Always verify MSD performance in EI before switching to CI operation. (See
“To Verify EI System Performance” on page 104.) Always set up the CI MSD in
PCI with methane as the reagent gas first, even if you are going to be using a
different reagent gas or going to run NCI.
Avoid tuning unless absolutely necessary; this will minimize PFDTD
background noise and help prevent ion source contamination.
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