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General Tips
Syringes are precision instruments. The care you take in using, handling and
storing them will dictate their accuracy, reproducibility, and lifetime; also,
the quality of the resulting chromatogram can be affected by a damaged syringe.
Routinely inspect the syringe for damage including hairline cracks. Discard
any syringe with a potentially unsafe barrel. The needle’s tip must be
free of barbs which could potentially rupture the septum and produce particles
that might clog the needle, or lodge in the injection port and damage the chromatographic
system.
If your syringe contains a PTFE tip, be sure to replace the plunger and tip
assembly immediately if any metal is exposed. The exposed metal scrapes the
glass of the syringe barrel, producing glass fragments that cut grooves in the
PTFE tip. These grooves allow sample to leak past the tip.
Caustic samples or cleaning solutions that seep under the PTFE tip can destroy
the sharp barb that holds the tip onto the plunger. The tip, so loosened, could
slip off during sample aspiration.
Between samples, the syringe should be flushed 5 – 10 times its total
capacity to eliminate carryover. Draw sample and expel the first several flushes
to waste to avoid contamination of the sample.
Never store a syringe without first cleaning it and then wiping dry all external
surfaces.
Recommended Cleaning Procedure:
A syringe should be flushed with approximately 5-10 times its total capacity to eliminate carryover between samples. This is achieved by repeatedly drawing and expelling solvent/sample from the syringe. To avoid contaminating the sample, the first 2-3 washes should be discarded to waste.
- Appropriate solvents are those that dissolve the contaminating substances.
Methanol, methylene chloride, acetone and acetonitrile are common. For storage,
the final rinsing should be with deionized water followed by acetone.
- Do not immerse the entire syringe in the solvent; this may damage the adhesives
holding parts of the syringe together.
- To unblock a needle, remove the plunger and fill the barrel with solvent
using another syringe. Insert the plunger and push solvent through the needle.
- Heating will remove semivolatile substances. Remove the plunger before heating.
Fixed needle syringes can be heated to 70 °C. Removable needle syringes
can be heated to 120 °C. Please refer to the syringe’s specific
instructions.
- A needle cleaning kit (Cat. No. 21578) and syringe cleaning solution (Cat.
No. 20742) are available from Supelco. The Hamilton syringe cleaner (Cat.
No. 20770-U) uses heat and vacuum to clean and restore performance.
Syringe Lubrication
Syringes do not require any lubricating grease. Grease may cause a variety
of problems including: sample cross contamination, seizing of the plunger in
the barrel or barrel damage. Minimize the use of a dry syringe; for lubrication,
use an appropriate solvent that is compatible with the sample.
Tips to Assure Accuracy and Precision
Grasp the syringe only by the flange and plunger button. By doing so, variations
in liquid measurement due to body heat are avoided.
Pump the plunger with the syringe needle immersed in the fluid to be transferred
to expel any trapped air in the needle and syringe.
If the plunger is accidentally removed from the syringe barrel, wipe it carefully
with a lint-free tissue. Reinsert the plunger into the barrel and pump deionized
water or acetone through the needle and syringe. In the case of plungers with
PTFE tips (like Hamilton’s Gastight syringes), re-wet the PTFE plunger
tip prior to reinserting it into the barrel. Avoid touching the exposed plunger
since any abrasions, scratches, or oil from one’s fingers will often
interfere with proper plunger operation.
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