Ci Autotune - Agilent Technologies 5977B Series Operating Manual

CI Autotune

After the reagent gas flow is adjusted, the lenses and electronics of the MSD
should be tuned. (See
Perfluoro-5,8-dimethyl-3,6,9-trioxidodecane (PFDTD) is used as the calibrant.
Instead of flooding the entire vacuum chamber, the PFDTD is introduced
directly into the ionization chamber through the GC/MSD interface by means
of the gas flow control module.
After the source is changed from EI to CI, or vented for any other reason, the MSD must
C A U T I O N
be purged and baked out for at least 2 hours before tuning. Longer bakeout is
recommended before running samples requiring optimal sensitivity.
There is a PCI autotune for methane only, as there are no PFDTD ions
produced by other gases in positive mode. PFDTD ions are visible in NCI for
any reagent gas. Always tune for methane PCI first, regardless of which mode
or reagent gas you wish to use for your analysis.
There are no tune performance criteria. If CI autotune completes, it passes.
EMV at or above 2600 V, however, indicates a problem. If your method requires
EMV set at +400, you may not have adequate sensitivity in your data
acquisition.
Always verify MSD performance in EI before switching to CI operation. (See
C A U T I O N
EI System Performance"
you are going to run NCI.
5977B Series MSD Operating Manual
"Reagent gas settings"
on page 108.) Always set up the CI MSD in PCI first, even if
Operating in CI Mode
on page 122.)
5
"To Verify
121