Cellulose Acetate (CA) Membranes FAQ

Sterlitech Cellulose Acetate (CA) membranes are made from cellulose diacetate. These membrane filters also have an integral nonwoven polyester (polyethylene terephthalate) support layer. When evaluating application compatibility, both materials should be considered.

A. Each cellulose membrane filter offers unique performance characteristics for different laboratory and life science applications: Cellulose Acetate (CA) membrane filters provide very low protein binding, making them ideal for protein recovery, cell culture media, and biological sample filtration. Sterlitech CA membranes include an integral polyester (PET) support layer for improved strength and easier handling. Nitrocellulose (NC) membrane filters are commonly used for protein binding and microbiological applications. Most commercial NC membranes are actually composed of a blend of nitrocellulose and cellulose acetate, making their performance essentially equivalent to Mixed Cellulose Esters (MCE) membrane filters.

Mixed Cellulose Esters (MCE) membrane filters offer high flow rates, a uniform pore structure, and excellent biocompatibility, making them widely used for microbiological analysis, sterility testing, and Silt Density Index (SDI) testing. Compared to CA membranes, MCE membranes have higher protein binding and are more fragile because they do not include a support layer. Regenerated Cellulose (RC) membrane filters combine the low protein binding and natural hydrophilicity of cellulose with excellent solvent resistance. Because RC membranes do not require wetting agents, they are well suited for protein filtration, organic solvent filtration, and other demanding analytical applications.

Yes. Sterlitech Cellulose Acetate (CA) membrane filters contain a proprietary surfactant that enhances the membrane's hydrophilicity and ensures rapid, uniform wetting with aqueous solutions. This improves filtration performance and helps the membrane deliver consistent flow rates in laboratory, biological, and protein filtration applications.

Excluding the polyester support layer, Cellulose Acetate (CA) membrane filters are composed entirely of cellulose acetate polymer. There may be a very small amount of residual lignin present as a trace component. This minimal lignin content does not affect the performance, purity, or reliability of CA membrane filters in typical laboratory, analytical, and sample filtration applications.

A. Cellulose Acetate (CA) membrane filters are ideal for protein filtration and other biological applications because they offer very low protein binding, maximizing protein recovery and minimizing sample loss. They provide high flow rates with protein-rich solutions and are commonly used for filtering proteins, enzymes, tissue culture media, sera, and other biological fluids. CA membrane filters are naturally hydrophilic, allowing easy wetting with aqueous solutions, and offer good chemical resistance and compatibility with low molecular weight alcohols. An integral nonwoven polyester (PET) support layer provides added strength, dimensional stability, and resistance to tearing or curling, making the membranes easy to handle. They can also withstand steam sterilization up to 135°C, making them suitable for a wide range of laboratory, biopharmaceutical, and life science applications.

Cellulose acetate (CA) and nitrocellulose (MCE) membranes will last 2 1/2 to 3 years before reverting to their natural hydrophobic states.  Nylon, on the other hand, is naturally hydrophilic so it does not have a shelf life. An easy test for older membranes is to perform a "wetting out" test.  Dipping a small portion of the membrane into water (hydrophilic membranes) or an alcohol (hydrophobic membranes) works well.  If the membrane absorbs the material, or "wets out", it has not gone past the shelf life.