Selection Guide: Membranes and Devices for Sterile Filtration of Liquids

Pall offers the widest selection of products to meet your specific sterile filtration needs. Our filtration membranes are available in laboratory device configurations that process volumes from < 5 mL to hundreds of liters. Selecting the most appropriate Effective Filtration Area (EFA) will maximize throughput and minimize filter changes. The greater the volume being filtered, the larger the filter diameter you should choose. However, because hold-up volume (fluid retained in the filter) increases with filter diameter, smaller-volume devices should be used for small-volume or expensive samples.

Small-volume Samples

For small sample volumes, sterile syringe filters are available. Sterile syringe filters have a luer lock inlet that will connect directly onto a syringe for easy filtration of your sample. These devices can rapidly filter small volumes and are available with diameters of 13, 25, 32, or 37 mm.

Throughput*	Device	EFA	Hold-up
1 - 10 mL	13 mm Acrodisc® syringe filter	1.0 cm2	< 30 µL
5 - 100 mL	25 mm Acrodisc syringe filter	2.8 cm2	< 70 µL
20 - 150 mL	32 mm Acrodisc syringe filter	5.8 cm2	< 100 µL
10 mL - 1 L	AcroCap™ device	15 cm2	< 2 mL

Mid-volume Samples

For filtration up to a few liters, a range of medium-size filters are available. These are typically a flat membrane in a 50 mm or larger diameter device, and are available in configurations for either positive pressure filtration or vacuum filtration.

Throughput*	Device	EFA	Hold-up
10 mL - 1 L	AcroCap™ device	15 cm2	< 2 mL
100 mL - 5 L	AcroPak™ 20 device	20 cm2	< 2.5 mL
100 mL - 5 L	VacuCap® 60 device	30 cm2	< 1.2 mL
100 mL - 5 L	VacuCap 90 device	60 cm2	< 3.4 mL
5 - 25 L	AcroPak 200 capsule	200 cm2	< 6 mL

Large-volume Samples

Larger volumes (> 5 liters) may require a capsule filter with pleated membrane. A capsule filter incorporates a larger surface by using a pleated membrane design. This larger membrane surface area allows for both faster filtration and higher volumes to be filtered. Capsule filters are ideal for positive pressure filtration and can operate at higher pressures. The volume recommendations presented below are intended as a general guide to selecting the most appropriate device.

Throughput*	Device	EFA	Hold-up
10 - 100 L	AcroPak 500 capsule	500 cm2	< 30 mL
10 - 100 L	AcroPak 1000 capsule	1000 cm2	< 45 mL
10 - 1500 L	AcroPak 1500 capsule	1500 cm2	n/a

* Total throughput (capacity) of a filter depends on the characteristics of the fluid being filtered, such as the extent of microbial contamination, viscosity, and particulate load.

Pall offers a range of membrane discs and devices to meet your specific filtration needs. Our liquid filtration membranes are available in configurations that process from > 5 mL to 100 liters. Choose from these membranes:

Direct Flow Filtration Membrane Selection

Membrane	Type	Characteristics
Supor®	Hydrophilic polyethersulfone (PES)	High flow rates and throughputs Low protein binding Extensive drug compatibility
Fluorodyne® II	Hydrophilic polyvinylidene fluoride (PVDF)	High flow rates Extremely low pressure drop Exceptional strength Low protein binding Low extractables Broad chemical and temperature resistance
Ultipor®	Nylon 6,6	Industry standard for pharmaceutical filtration Broad solvent and chemical compatibility Low extractables
Posidyne®	Positively-charged Nylon 6,6	Enhances bioburden and pyrogen removal from aqueous solutions
Versapor®	Acrylic copolymer on a nonwoven support	Designed for applications requiring excellent retention properties combined with tensile strengths in excess of 200 bar (3000 psi) Economical choice for clarification
HT Tuffryn®	Polysulfone	Low protein binding Durable and easy to handle

When selecting a filtration membrane, consider the fluid characteristics of your sample and the degree of filtration required. The more particulate-laden and/or the higher the protein concentration in a solution, the more difficult it is to filter. These types of liquids may clog filters prematurely, and multiple filters may be needed to process single batches, increasing the cost of filtration. The most efficient way to filter these solutions is to choose a filter with a built-in prefilter or a filter with more EFA. Pall Life Sciences can recommend an efficient filter for your toughest application needs. These include:

• Acrodisc® PF Syringe Filters with Supor® PES Membrane for Sterile Filtration
• VacuCap® PF Vacuum Filtration Devices
• AcroPak™ 20 Filters with Supor® Membrane
• AcroPak™ 200 Capsule with Supor® Membrane 
• AcroPak™ 500, 1000, & 1500 Capsules with Supor® Membrane

Built-in Prefilter Enhances Throughput of Viscous, Particulate-laden or Proteinaceous Solutions

Serum-free media and buffers are typically not as challenging to filter as serum-containing media. However, it is common for protein concentrations to be very low in these solutions. With this in mind, it is very important to choose a low protein-binding syringe filter. Binding is the property of substances to have an affinity for filter media or other filter components. When filtering solutions with low protein concentrations, certain filters can lead to the loss of active proteinaceous ingredients. To minimize protein loss during filtration of proteinaceous solutions, choose products with Pall's Supor membrane:

• Acrodisc® Syringe Filters with Supor® PES Membrane for Sterile Filtration
• AcroCap™ Positive Pressure Devices
• VacuCap® & VacuCap PF Vacuum Filtration Devices
• AcroPak™ 20 Filters with Supor® Membrane
• AcroPak™ 200 Capsule with Supor® Membrane 
• AcroPak™ 500, 1000, & 1500 Capsules with Supor® Membrane

Read more about filtration of dilute protein and DNA solutions.

For process development applications, choose products from Pall’s UpScale^SM program. Pall’s UpScale program helps shorten development time by providing products with the same media and consistent materials of construction for all phases of development, from R&D to pilot to full-scale production. Pall’s range of scalable products provides consistent, reproducible, and predictable results regardless of scale. You can reduce evaluation bottlenecks and free up resources to concentrate on process optimization or other research. Our separation and filtration products will meet your needs at the laboratory level and as you move into production. Choose from these scalable products for sterile filtration:

• Acrodisc Syringe Filters Optimized for Scale Up (volumes up to 150 mL)
• AcroPak 20 Filters with Supor® Membrane (volumes up to 5 liters)
• AcroPak 200 Filters with Supor Membrane (volumes up to 20 liters)
• AcroPak 500, 1000, and 5000 Capsules with Supor Membrane (volumes up to 150 L)
• AcroPak 20 Filters and AcroPak 200 Capsule with Fluorodyne® II Membrane ( volumes up to 20 L)
• AcroPak 400 and 800 Capsules with Fluorodyne II Membrane (volumes up to 150 L)

Even if all of the other components of your freezing media have been filter sterilized, DMSO can add contaminants that may not be detected until after the cells are removed from storage and thawed. Many commonly-used filter materials are unstable in DMSO because it is an aggressive solvent. The DMSO-safe Acrodisc syringe filter can be used to filter-sterilize solutions containing DMSO to eliminate surprise contamination upon thawing cells.

Mycoplasma contamination in cell cultures can be difficult to detect. Most often, the only real solution is to discard all suspect cultures and reagents. Devices with 0.1 µm Supor membrane can be used for added assurance to filter liquids where the potential for mycoplasma contamination exists. This membrane is routinely tested for retention of mycoplasma (A. laidlawii). Pall's 0.1 µm Supor membrane devices are available in:

• Acrodisc® Syringe Filters with Supor® PES Membrane for Sterile Filtration
• AcroCap™ Positive Pressure Devices
• AcroPak™ 20 Filters with Supor® Membrane
• VacuCap® & VacuCap PF Vacuum Filtration Devices
• AcroPak™ 500, 1000, & 1500 Capsules with Supor® Membrane

Read more about the effects of mycoplasma contamination in tissue culture applications.