Installing 7890 GC Columns 2
5977B Series MSD Operating Manual 37
Conditioning columns
Conditioning a column before it is connected to the GC/MSD interface is
essential. (See “To Condition a Capillary Column” on page 41.)
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 MSD ion source. This decreases MSD sensitivity,
and makes cleaning the ion source necessary.
Column bleed is most common in new or poorly crosslinked 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/MSD 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 procedures for the 5977B Series MSDs may be
different from that for previous MSDs. Using the procedure from another
instrument may not work, and may damage the column or the MSD.
• 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 or
use the self tightening column nuts.
• Always wear clean gloves when handling columns, especially the end that
will be inserted into the GC/MSD 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 MSD power. If the foreline pump is off,
hydrogen will accumulate in the MSD and an explosion may occur. Read “Hydrogen
Safety” on page 23 before operating the MSD with hydrogen gas.
Always wear safety glasses when handling capillary columns. Avoid puncturing
your skin with the end of the column.
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