7-2 The Direct Insertion Probe
Introduction
The direct insertion (DI) probe is designed to admit solid samples, or liquid
samples not sufficiently volatile to inject via the reference inlet, into the ion
source. The DI probe is inserted into the instrument source via the probe
insertion lock, which must be fitted to the instrument prior to using the probe.
The sample is loaded into a quartz sample cup, which is then located in the
end of the probe. The cup is held in position by a thin strip of tungsten foil. A
heating element and thermocouple are also located at the end of the probe.
A fine, stainless steel capillary, is wound close to the heater element. The
capillary carries cooling water, which allows the sample temperature to be
finely controlled as well as providing rapid probe cooling.
The thermocouple monitors the probe temperature. The heating current is
controlled by MassLynx to maintain the required temperature ramp rate and
final temperature.
Note: For more information about using the DI probe in FI mode, see
Chapter 9 FI/FD Operation on page 9-1.
Installing the probe insertion lock
To install the probe insertion lock:
1. Remove the GC interface.
See also: Installing the GC interface on page 6-3.
2. Ensure that the probe insertion lock valve is in the closed position.
See also: Figure titled “Probe insertion lock:” on page 7-3.
Warning: To avoid burn injuries, take care when working with
the GC interface and GC oven as they operate at a high
temperatures.
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