4 Installing 7890 GC Columns
Conditioning columns
7000/7010 Series TQ GC/MS Operating Manual 75
Conditioning columns
Conditioning a column before it is connected to the GC/MS interface is essential.
A small portion of the capillary column stationary phase is often carried away by
the carrier gas. This is called column bleed. Column bleed deposits traces of the
stationary phase in the MS ion source. This decreases MS sensitivity and makes
cleaning the ion source necessary.
Column bleed is most common in new or poorly cross-linked columns. It is much
worse if there are traces of oxygen in the carrier gas when the column is heated.
To minimize column bleed, all capillary columns should be conditioned before
they are installed in the GC/MS interface.
Conditioning ferrules
Heating ferrules to their maximum expected operating temperature a few times
before they are installed can reduce chemical bleed from the ferrules. Thermal
cycling ferrules to their maximum operating temperatures, prior to running your
application, will help reduce leaks from the assembly.
Tips and hints
• The column installation procedure for the 7000/7010 Series TQ GC/MS is
different from that for previous MSs. Using the procedure from another
instrument may not work and may damage the column or the MS.
• You can remove old ferrules from column nuts with an ordinary pushpin.
• Always use carrier gas that is at least 99.9995% pure.
• Because of thermal expansion, new ferrules may loosen after heating and
cooling a few times. Check for tightness after two or three heating cycles.
Agilent recommends use of their new self-tightening nuts on the MS transfer
line, inlet, and GC detector.
• Always wear clean gloves when handling columns, especially the end that
will be inserted into the GC/MS interface.
If you are using hydrogen as a carrier gas or for the JetClean system, the
hydrogen gas flow must be off before turning off the MS power. If the foreline
pump is off, hydrogen will accumulate in the MS and an explosion may occur.
Read “Hydrogen Safety” on page 21 before operating the MS with hydrogen gas.
Always wear safety glasses when handling capillary columns. Use care to
avoid puncturing your skin with the end of the column.
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