60 5975 Series MSD Operation Manual for MassHunter
3 Operating in Electron Impact (EI) Mode
The EI GC/MSD Interface
The GC/MSD interface (Figure 12) is a heated conduit into the MSD for the
capillary column. It is bolted onto the right side of the analyzer chamber, with
an O-ring seal. It has a protective cover which should be left in place.
One end of the GC/MSD interface passes through the side of the gas
chromatograph and extends into the GC oven. This end is threaded to allow
connection of the column with a nut and ferrule. The other end of the
interface fits into the ion source. The last 1 to 2 millimeters of the capillary
column extend past the end of the guide tube and into the ionization chamber.
The GC/MSD interface is heated by an electric cartridge heater. Normally, the
heater is powered and controlled by Thermal Aux #2 heated zone of the GC.
For 6850 Series GCs, the heater is connected to the auxiliary thermal zone.
For the 7820A Series GC’s, the heater is either connected to the rear inlet
thermal zone for single inlet models or connected to the manual valve thermal
zone for dual inlet models. The interface temperature can be set from
MassHunter Data Acquisition or from the gas chromatograph. A sensor
(thermocouple) in the interface monitors the temperature.
The GC/MSD interface should be operated in the 250 to 350 C range. Subject
to that restriction, the interface temperature should be slightly higher than the
maximum GC oven temperature, but never higher than the maximum column
temperature.
The EI GC/MSD interface can only be used with the EI ion source. However,
the CI GC/MSD interface can be used with either source.
See Also
“To Install a Capillary Column in the GC/MSD Interface” .
WARNING
The GC/MSD interface operates at high temperatures. If you touch it when it is hot,
it will burn you.
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