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Problem Possible Cause(s) Suggested Action(s)
Blocked needles
• Sample material or contaminants may be trapped
inside the needle.
• The needle may not have been properly cleaned.
Remove the plunger and use a second syringe to fill
the blocked syringe with solvent. Then, insert the
plunger and gently push solvent through needle.
Important: Try to use a cleaning agent that is
appropriate for the contaminant. Common choices
are methanol, methylene chloride, acetontrile,
and acetone.
Rust
Note: even minor rust can cause the
plunger to become stuck in the barrel.
• During normal use, the shaft rubs against the glass
walls of the barrel. This gradually wears away the
rust-resistant metal on the shaft's surface.
• Rusting happens most rapidly when using water or
solvents that may contain (or absorb) water.
To slow this process, remove the water from the
syringe at the end of each day.
1. Rinse the syringe several times with a "dry"
solvent, such as acetone.
2. Remove the syringe from the autosampler,
and wipe the plunger dry with a lint-free cloth.
3. Let syringe and plunger air dry.
"Ring around the neck"
(A dark ring between the top
of the barrel and the end of
the volume scale.)
• Skin oils and other organic material.
• Fine metal and glass particles from the syringe
plunger and barrel may be rubbing together. Once
this happens, the plunger may bend if used further.
• Never touch the plunger shaft with your fingers.
• If build-up appears when water is the solvent:
rinse syringe with acetone and wipe the plunger
clean at the end of each day.
Loose plungers
Accompanied by syringe leaks and
area count reproducibility problems.
• The syringe is nearing the end of its useful life. • Replace the syringe.
• Note: Plungers normally feel "loose" when non-
polar solvents (like hexane and toluene) are used.
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