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Operating in Chemical Ionization (CI) Mode 4

5975 Series MSD Operation Manual for MassHunter 103

The CI GC/MSD Interface

The CI GC/MSD interface (Figure 20) 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 and has a protective cover which should be left in place.

One end of the interface passes through the side of the GC and extends into

the oven. It 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.

Reagent gas is plumbed into the interface. The tip of the interface assembly

extends into the ionization chamber. A spring-loaded seal keeps reagent gases

from leaking out around the tip. The reagent gas enters the interface body and

mixes with carrier gas and sample in the ion source.

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.

The interface temperature can be set from MassHunter or from the gas

chromatograph. A sensor (thermocouple) in the interface monitors the

temperature.

This interface is also used for EI operation in CI MSDs.

The 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.

Agilent Technologies 5975 User Manual

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