Air bubble in HPLC Syringe

[clinephd]

Hello,
does anyone have any tips for me on how to avoid air bubbles in my injection syringe? I use water as mobile phase and water as rinsing medium of the autosampler, however, adding acetonitrile disturbed my measurements.
Kind regards

[uzman]

Degassing the water may help.

You may also rinse the syringe with acetonitrile first , then use water .This will clean the inside surface of syringe so reduce the possibility of bubble formation.

[clinephd]

Thank you for your reply

Water is already degassed..

How often do you think I should rinse the syringe with ACN?

[uzman]

Logically , before starting a sequence ,but it also depends on the frequency of bubble formation.

Replacing the syringe with a new one, may also help.

[bunnahabhain]

Back in university we used to take the plunger out of the syringe, and push it gently on a flat surface with a little rubbing. Make sure the plunger is not tilted. The idea isto make the PTFE seal a little bit thicker. This usually helped for a while but sooner or later they must be replaced.
Good luck!
Jörg

[clinephd]

Thank you both for the tips; I will try them next week!