sterilfiltration

Sterilfiltration, also known as sterile filtration, is a filtration-based method used to remove microorganisms from liquids or gases to achieve aseptic conditions. It is widely employed for heat-sensitive products in pharmaceuticals, biotechnology, food and beverage, and clinical settings, where conventional sterilization methods such as autoclaving are impractical.

The process relies on membrane filters that physically retain microorganisms by size exclusion. Commonly, sterile filtration uses pore sizes around 0.2 or 0.22 micrometers to remove bacteria from liquids. Viruses, however, are typically smaller and may require additional steps such as nanofiltration, viral inactivation, or combined therapies to ensure sterility. Filters are made from various materials, including cellulose acetate, polyethersulfone (PES), polyvinylidene fluoride (PVDF), and other hydrophilic polymers. The choice depends on the solution’s chemistry, extractables concerns, and compatibility with the product.

Sterilfiltration is performed under aseptic conditions and is often preceded by prefiltration to remove particulates and fouling agents. Critical aspects include filter integrity testing (for example, bubble point or pressure decay tests) and documentation to confirm sterility of the final product. Operators must manage flow rates, differential pressure, and potential adsorptive losses of target molecules or vitamins.

Applications span parenteral and ophthalmic solutions, biologics, culture media, and some beverages. While sterilfiltration avoids heat-related degradation, it carries risks such as filter fouling, leachables from filter materials, and the need for validated validation and aseptic handling. Proper design, testing, and containment are essential to ensure a consistent sterile product.