What filter should I use for HPLC?
The short answer: a 0.22 or 0.45 µm syringe filter, in a material compatible with your mobile phase, with low extractables.
Quick answer
Use a small-format (4–25mm) syringe filter at 0.22 µm or 0.45 µm, in a membrane material compatible with your sample solvent—PES or PVDF for aqueous mobile phases, PTFE for organic or aggressive solvents. Choose a low-extractable or HPLC-certified line if you're running trace-level or LC-MS methods.
Why material matters more than usual here
HPLC is sensitive to membrane extractables showing up as unexpected peaks or ion-suppression noise—more so than most other filtration applications. This is the one place where "any compatible membrane" isn't quite good enough; a low-extractable line is worth the extra cost.
Watch for analyte binding
If your analyte is basic or polar, check that your chosen membrane (especially nylon) doesn't bind it—low recovery at trace levels often traces back to this, not the method itself.
See our full HPLC and GC sample prep guide for the complete breakdown.
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