6-8
Ver.1.36
6.1.4 GC injection port
6.1.4.1 Septa
When the pyrolyzer is installed on a GC, the injection port is in close contact with the heat sink
adapter; therefore, the temperature of the septum is at least 50°C higher than its normal operating
temperature. This increases the silicon rubber septum’s susceptibility to thermal degradation. Our
experiences show that high quality septa will last about one month at injection port temperature of
300°C. However, once the septum is removed from the injector port, a new septum must be used. The
use of the supplied pretreated septa (see consumables list for details) will facilitate the removal of the
septum.
If the septum is stuck to the metal surface of the injector, cool the temperature down to 100°C or lower
and apply hexane to the septum to swell it for easy removal.
6.1.4.2 Insert liner
High boiling compounds from the pyrolyzates travel to the GC injection port via the pyrolyzer. If the
injection port temperature is low, such compounds tend to deposit on the interface needle and on the
glass insert liner. If this occurs, set the injector temperature to 350°C and allow it to bake for two to
three hours with the carrier gas on; remove the column during this bake-out. Inspect the injection port
inner wall every one to two weeks.
6.1.4.3 Column
Column degradation depends primarily on the analytical conditions and the nature of the pyrolyzates.
Tars and reactive gases such as HCl from pyrolysis can degrade part of or the entire column.
Generally, tars are often impossible to remove completely by rinsing the column with a solvent
because tars are baked and bonded tightly to the inner wall of the column at high temperatures. If the
degradation occurs due to strong acidic gasses such as HCl or HBr, the column cannot be restored to
its original performance. If the sample is expected to generate these acidic gases, put some glass
wool or fiber coated with potassium hydroxide (a few percents) in the insert liner to protect the column.
6.1.4.4 Absorption trap tube
If an absorption trap set is installed in the split line of the GC injector, replace the trap tube (PY1-2216).
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