Lots of air with new solvent inlet filters

[koenvanderdrift]

We recently switched to PTFE solvent bottle inlet filters (Agilent # 3150-0958) on our 1100 system, which are part of Agilent's Biocompatibility kit. It costs quite of force to try to squeeze the filter into the tubing, so one would expect that the connection is tight. However when we purge we keep seeing air bubbles going through the tubing, and it looks like they are formed at the connection between the tube and the filter. Interestingly, it didn't happen with the older (SS) filters in the same solvent.

Does anyone have experience with these filters, and know what the recommended tubing (or way to attach them) is?

[asm]

Are you sure, that it is "air"?

Do you have problems with "air" in the system itself?

I would claim, that the 10µm of the filter is to small for a high flow. I think it is possible, that the pump is pumping more solvent then could flow through the filter and your "air" is just solvent vapor.

Normal "air" should be no problem as you have usually a degasser.

Solvent vapor shouldn't be a problem too, because this should disappear as soon as the pressure is rising behind the pump.

[koenvanderdrift]

No, I don't know if it is 'air', could be any gas coming from the solvent. I agree about the flow being too high, we will try to purge at 2 ml/min and see what happens. Thanks.

[uzman]

Try wetting the filter with methanol ( or ACN ) first , then proceed with your mobile phase.

PTFE materials needs wetting with organic solvent before using water , otherwise it resists flow since it is highly hydrophobic , this will cause partial vacuum forming inside the filter so the result is bubble forming.

[koenvanderdrift]

Soaking the filters in MeOH and sonicating them for 15 minutes did the trick, and we can purge our lines at 5 ml/min without problems.

[mirac_han]

If you have a online degaser module you dont worry this probem. Usually A small of air contain in the ptfe filter.it is normal. I think you have to use degased solvent.