HP 5973 MSD, Hardware Manual

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56
CI operation
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To perform CI autotune
After the reagent gas flow is adjusted, the lenses and electronics of the MSD should
be tuned. 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.
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.
C A U T I O N After the system has been switched from EI to CI mode, or vented for any other reason, the
MSD must be baked out for at least 2 hours before tuning. Longer bakeout is recommended
before running samples for optimal sensitivity.
Default (starting) CI tune parameters)
Reagent gas Methane Isobutane Ammonia EI
Ion polarity Positive Negative Positive Negative Positive Negative N/A
Emission 150
µΑ
50
µΑ
150
µΑ
50
µΑ
150
µΑ
50
µΑ
35
µΑ
Electron energy 150 eV 150eV 150eV 150eV 150eV 150eV 70
Filament 1 1 1 1 1 1 1 or 2
Repeller 3 V 3 V 3 V 3 V 3 V 3 V 30 V
Ion focus 130 V 130 V 130 V 130 V 130 V 130 V 90 V
Entrance lens (gain) 0 mV/amu 0 mV/amu 0 mV/amu 0 mV/amu 0mV/amu 0 mV/amu 0 mV/amu
Entrance lens offset 20V 20 20V 20 20V 20 25
EMVolts 1200 1200 1200 1200 1200 1200 1200
Gas Off Off Off Off Off Off Off On
Gas select valve A A B B B B N/A
Suggested flow 20% 40% 20 40 20 40 N/A
Source temp 250°C 150°C 250°C 150°C 250°C 150°C 230°C
Quad temp 106°C 106°C 106°C 106°C 106°C 106°C 150°C
Interface temp 320°C 280°C 320°C 280°C 320°C 280°C 280°C
Autotune Yes Yes No Yes No Yes Yes