Frequently Asked Questions

We have a Chemical Compatibility Chart that you can use for reference.

For lateral flow assays, membranes with high protein binding capacities are preferred.  Consequently, with their inherently low protein binding capacities, PES membrane filters are typically not used in these applications.

The polyethersulfone (PES) membranes used in the Sterlitech membrane filters have asymmetric pore structure.  The pore structure varies within the thickness of the membrane such that the largest openings occur on one side and the smallest openings occur on the opposite side.  When viewing the membrane with reflected light at low incidence angles, each side has a somewhat different visual appearance.  The side with the largest pores will appear more dull (or matte) than the side with the smallest pores
(which will appear shinier).  With a little bit of experience, most users can easily identify the sides.  The membranes can be used with either surface oriented upstream without affecting retention.  However, orienting the dull side upstream increases total throughput
while orienting the shiny side upstream allows for better analyses of the retained particles.

The polyethersulfone (PES) membrane filters have asymmetrical pore structure. The pore structure varies within the thickness of the membrane such that the largest openings occur on one side and the smallest openings occur on the opposite side. When viewing the membrane with reflected light at low incidence angles, each side has a somewhat different visual appearance. The side with the largest pores will appear more dull or matte than the side with the smallest pores. With a little bit of experience, most users can easily identify the sides. For optimal throughput, the PES membrane filters should be oriented so that side with the largest pores (the duller side) is facing upstream. For applications involving microscopic analyses of captured particles or microbes, the user may choose to orient the filter so that the side with the smallest pores (the shinier side) is facing upstream. This orientation may reduce throughput but it improves the likelihood of capturing particles of interest on the surface of the membrane instead of within the pore structure.

PES Membranes are low protein binding, PES membrane filters are ideal for tissue culture media sterilization, life science and microbiology fluid applications.