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Polycarbonate Membrane Filters

SPI-Pore™ and Whatman/GE™ brands


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Appearance of the pores in the SPI-Pore™ PCTE membrane filters Corrosion cast of a typical SPI-Pore™ PCTE membrane filter showing the spatial arrangement of the pores.
SPI-Pore Polycarbonate Membrane Filters

Available Products:

Disc filters
Black Membranes (SPI Pore only)
Epifluorescence Microscopy
Grease Coated Membrane Filters
Membrane Filter Holders
Standard White Membranes (SPI-Pore and Whatman/GE™)
PVP-Free Membranes for Chemotaxis

Sheet format
8" x 10" White Membrane Material, Cut Sheets


Why Polycarbonate Membrane Filters?

Ordinary depth-type membrane filters contain tortuous pores that capture particles via random entrapment. The result being some fraction of particles in the interior (interstices) of the membrane filter making them unavailable for observation on the surface by LM or SEM.

In contrast, polycarbonate filters contain uniform, cylindrical pores preferentially etched into the membrane, allowing for an even distribution of a collected sample in one plane across the entire exposed membrane surface.

Hence all samples are captured on a flat, smooth, glass-like surface. The precisely sized pores in a very narrow distribution ensure accurate separation or fractionation of samples by size.

Contaminant-free, these microporous screens are biologically inert, offer excellent chemical resistance, thermal stability, superior strength and negligible adsorption of filtrate. These factors combined with the unique filtration capabilities of the polycarbonate membranes make it a clear preference for a number of EM and LM applications including: Airborne Particulate Analysis (such as asbestos) Chemotaxis, Cytology, Histology, Paleontology, Parenterals and Water Analysis for asbestos and other suspended inorganics. The color of the most commonly purchased form of the product is white but in some situations the black form of the product is preferred.

The filtration and physical properties of PC membrane filters make them fairly unique and set them apart from membrane filters of other compositions giving them in many instance unique performance advantages.

Chemical Compatibility of PCTE membranes:
The membranes are surprisingly resistant to a number of organic solvents and inorganic liquids. Caution some solvents will instantly dissolve PCTE membranes and you should consult our solvent resistance information for more detail.

Fluorescence characteristics
All PCTE membrane filters, irrespective of the manufacturer are made from a polycarbonate that contains fluorescent pigmentation in the raw material. This most important and unique raw material is not available without this pigmentation system.

Birefringence:
All polycarbonate membrane filters, exhibit some amount of birefringence because polycarbonate crystallizes and has a crystalline texture. In a polarizing microscope, the individual crystallites show up as a fine "pepper" like appearance.

Maximum use temperature:
The polymer starts to soften at approximately 150°C and will melt at 240°C. If your requirements involve work at higher temperatures, we recommend using either a) Anopore® aluminum oxide membrane filters or b) SPI-Pore™ Silver Membrane Filters.

Do the membranes have a charge?
The polycarbonate track etch membranes do not have an inherent positive or negative charge. They do act in the same way as the dielectric film in a capacitor and static electricity will build up on it. This static charge will cause the membrane to act as if it has a charge but this charge is not a property of the membrane; it is the result of the environment in which the membrane has been exposed. The Zerostat® antistatic gun has proven effective in terms of neutralizing any charge that might build up on a membrane.


SPI-Pore™ Polycarbonate Membrane Filters

SPI-Pore polycarbonate membrane filters are manufactured using unique proprietary manufacturing technology and also meet or exceed industry standards for high-grade polycarbonate membranes on all property levels:

Membrane characterization:
A large amount of information about the physical characteristics of the SPI-Pore track etch polycarbonate membrane filters is described here.

SPI-Pore vs. Whatman/GE™ Polycarbonate Track Etch Membrane Filters
Since there is only one manufacturer in the world of the special liquid monomer from which the polycarbonate film material is made, the two brands of membrane filters are similar. But because different manufacturing processes are used different thicknesses of base material film are needed. For most pore sizes the membrane thickness the SPI-Pore membranes is thinner than the Whatman/GE™ brand. This has important implications on flow rates.


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