Chromatography Forum

Which type of membrane filter has the lowest extractable?

Teflon. But the selection of a syringe filter depends on the suitibility of the method (which you demonstrate in your AMV protocol and final report).

TEFLON is hydrophobic. For aqueous samples I need a hydrophilic membrane. Any hydrophlic membrane with the lowest extractable?

Thanks!

TEFLON is hydrophobic. For aqueous samples I need a hydrophilic membrane. Any hydrophlic membrane with the lowest extractable?

Thanks!

Again PTFE, this time hydrophylic:
https://www.membrane-solutions.com/ptfe_hydrophilic.htm

Depending on your definition of "low", this can be somewhat technique driven.
You get lower amounts of extractables if you don't collect the first bit to make it through the filter. Once you've found a decent filter and defined "bit" to your liking, you're there.

PTFE usually has very low extractables, but you are right they are hydrophobic. If you need hydrophilic low extractable membrane, Hydrophilic PVDF is somewhat low. It all depends on your application, you can give it a try.

Another thing to consider is the interaction of your target analyte with the filter material. Diquat will adsorb completely on a nylon filter membrane at neutral pH but will pass through completely at <2pH. Some carbamates require PVDF to pass though unretained.

PTFE is about the only one I have never had problems with retention of analytes on, but I am sure there is something that will stick to it, if I finally run enough different analytes.

Best thing to do is pick a few and try them out with your samples. You can usually get some free samples of each type from places like Phenomenex or Restek, or Environmental Express, ect if you ask.