8 Maintaining the COC Inlet
To Replace the Fused Silica Needle in a Syringe for the COC Inlet
136 Maintaining Your GC
To Replace the Fused Silica Needle in a Syringe for
the COC Inlet
The fused silica needle and syringe are only used with the cooling tower and duckbill septum
for manual, on-column injections onto 200-µm columns.
1 Gather the following:
• New fused silica syringe needle, see “Consumables and Parts for the Cool On-Column
Inlet” on page 120.
• Solvent
Wear safety glasses to protect your eyes from flying particles while handling, cutting, or
installing glass or fused silica capillary columns. Use care in handling these columns to
prevent puncture wounds.
2 Loosen the retaining nut and remove the old needle.
3 Hold the syringe vertically and insert the new fused silica needle so it is visible inside the
syringe barrel. If the needle cannot be inserted into the syringe barrel, the PTFE ferrule may
be blocked. You may need to replace the ferrule.
4 Push the plunger down until it bottoms. The needle will be flush with the plunger end.
5 Finger-tighten the retaining nut. Pull the needle gently to be sure the PTFE ferrule has
formed a tight seal with the needle. Tighten the retaining nut further, if necessary.
6 Loosen the retaining nut just enough so the needle is again free.
7 Depress the syringe plunger slowly until it pushes the needle to the end of the barrel, then
finger-tighten the retaining nut.
8 Use a solvent to rinse the syringe and check for leaks or blocks. Leaks may be fixed by
further tightening the retaining nut. Blocks or serious leaks require repeating this
procedure.
Fused silica needle
PTFE ferrule
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