4 Operating in EI Mode
92 5975/5977 Series MSD Operating Manual
The GC/MSD Interface
The GC/MSD interface (Figure 24 on page 93) 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 mm 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. The
interface temperature can be set from OpenLAB 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 extractor ion source requires a tip seal (G3870-20542). The standard EI
sources constructed of stainless steel or inert material do not need a tip seal.
See also
“To Install a Capillary Column in the GC/MS Interface Using the Self-Tightening
Column Nut” on page 36.
The GC/MSD interface operates at high temperatures. If you touch it when it is
hot, it will burn you.
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