Frequently Asked Questions

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

Yes, the cellulose acetate (CA) membranes contain a proprietary surfactant.  The surfactant is used to ensure the CA membrane filters have good wettability.

Cellulose acetate (CA) membranes are made of entirely cellulose acetate polymer.  These membrane filters have the lowest protein binding of the filer types in question and typically have the greatest throughput when used with proteinaceous solutions.  They are also used in applications where maximum protein recovery is critical. The Sterlitech CA membranes have an integral nonwoven polyester support layer for improved strength and handling ease.

Ideally, nitrocellulose (NC) membranes would be made entirely of nitrocellulose polymer. However, almost all commercially available filtration grade membrane filters labeled as “nitrocellulose” are actually composed of membranes made with a mixture of nitrocellulose and cellulose acetate polymers.   This is because pure nitrocellulose membrane filters are very difficult to manufacture with accpetable characteristics. In an effort to provide clarity to consumers, some manufactures refer to membranes containing a mixture of nitrocellulose and cellulose acetate polymers as mixed cellulose esters (MCE) membranes.  In almost all applications, commercial nitrocellulose (NC) membrane filters and mixed cellulose esters (MCE) membrane filters are equivalent.

Mixed cellulose esters (MCE) membrane filters do not have a discrete support layer and are somewhat fragile and more difficult to handle
when compared to CA membrane filters.  MCE membranes exhibit greater protein binding than CA membranes.  However, MCE membranes tend to have more uniform pore structure and intrinsically greater clean water flow.  MCE membrane filters have very good biocompatibility and are commonly used for microbiological studies.  MCE filters are also traditionally used for silt density index (SDI) measurments.

Regenerated cellulose (RC) membranes are made by chemically treating nitrocellulose membranes so that the material reverts back to natural
cellulose.  RC filters have the very good solvent resistance of traditional filter papers but with the much finer retention characteristics of polymer membrane filters.   Additionally, regenerated cellulose is inherently hydrophilic and RC filters do not contain the wetting agents required by MCE and CA membrane filters.

Cellulose acetate (CA) membrane filters are one of the lowest protein binding filters available. They will generally have greater throughput with proteinaceous solutions when compared to other membrane filters. CA membrane filters are ideal for filtration of protein and enzyme solutions, tissue culture media and serums, biological fluids, and similar applications where maximum recovery of protein is critical.

CA membranes are manufactured with an integral nonwoven polyester support layer resulting in a dimensionally stable strong membrane that is easier to handle and resistant to curling. The filters have superior resistance to tearing and can withstand steam sterilization up to 135°C. They are suitable for use at elevated temperatures.

CA membranes are hydrophilic and readily wet in water and aqueous solutions. They have good chemical resistance and can be used with low molecular weight alcohols. 

Not including the polyester support layer, the Cellulose Acetate (CA) membrane filters are composed entirely of cellulose acetate polymer.  There may, however, still be a small amount of residual lignin present. 

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.