How to choose a membrane filter material

Membrane material determines what a filter is chemically compatible with, whether it binds or releases the compounds passing through it, and how well it holds up under a given solvent or pressure. Getting the material family right first narrows everything downstream—pore size, diameter, and format.

The five common material families

Material	Wetting	Typical strength	Watch for
PES (polyethersulfone)	Hydrophilic	Low protein binding, fast flow, broad aqueous compatibility	Not suited to strong organic solvents
PTFE (polytetrafluoroethylene)	Hydrophobic (hydrophilic variants exist)	Broad chemical resistance, including aggressive solvents and gases	Hydrophobic PTFE will not wet with aqueous samples without a solvent pre-wet or a hydrophilic-treated variant
Nylon	Hydrophilic	Good with alcohols and many organic solvents	Can bind some polar and basic compounds—relevant for sensitive analytical work
PCTE (polycarbonate track-etch)	Hydrophilic	Precise, uniform, cylindrical pores; low extractables	Lower dirt-holding capacity than depth media; not a first choice for heavily particulate samples
Glass microfiber	Hydrophilic	High dirt-holding capacity, good as a pre-filter or coarse clarifier	Depth structure means pore rating is nominal, not absolute—less suited where an exact cutoff matters

Start from chemical compatibility

Match the membrane to the solvent or sample matrix first. Aqueous and biological samples generally pair well with PES; aggressive solvents, strong acids/bases, or gas filtration generally call for PTFE. Nylon sits in between for many organic solvents but is worth checking against your specific analyte if you're doing trace-level analytical work, since some compounds can adsorb to it.

Consider what the membrane might bind or shed

Low-protein-binding claims matter for biological and pharmaceutical samples where analyte loss to the membrane surface would skew results. Extractables matter for analytical and PFAS-sensitive workflows, where a membrane itself could introduce background contamination. PCTE's simple, well-defined pore geometry is one reason it's common in particulate-counting and microbiological applications where a precise, absolute pore cutoff is the point.

Match structure to the job

Track-etched membranes (PCTE) have a flat, uniform surface with cylindrical pores—useful when you need an absolute size cutoff or a clean surface for microscopy/counting. Depth media like glass microfiber trap particles throughout their thickness, giving higher capacity before clogging but a less precise cutoff. If a sample is heavily loaded with particulate, a glass microfiber pre-filter ahead of a tighter final membrane often outperforms trying to do both jobs with one filter.

Confirm before you standardize

These are general material characteristics, not a substitute for the specification sheet of the exact product you're evaluating—manufacturers vary in surface treatments, binding data, and extractables testing even within the same base material. Request the spec sheet or a documented comparison for the exact SKUs you're considering before locking in a method.