Syringe Filter Selection Guide - Part 3 of 4
Consider the following when choosing the best filter for your analytical application:
Part 3: Most Appropriate EFAThe particulate contained within a fluid affects the life of a filter. As particles are removed from the fluid, they block pores and reduce the useable portion of the filter. Particulate-laden fluids generally plug a filter more quickly than "clean" fluids. Increasing the Effective Filtration Area (EFA) can lengthen the life of a filter.
Filters come in a variety of sizes ranging from the area within a single well of a 96-well plate, to spin filters and syringe tip filters. Acrodisc syringe filters are available in 25 mm Acrodisc PSF syringe filters as well as in 13 and 4 mm diameters for smaller sample volumes. All are available in a variety of membrane and pore size choices.
Hold-up VolumeAnother aspect of choosing the right filter size is the hold-up volume. This is the volume of liquid remaining in the filter after use. A filter with a low hold-up volume is recommended for use with expensive fluids or those with limited availability.
What device size will assure complete sample filtration with minimal hold-up volumes? Pall offers a broad range of device sizes. The minispike outlet, available on the 13 mm device, allows for minimal sample hold up and easy dispensing into autosampler vials. Additional options include the 4 mm Acrodisc syringe filter, the Nanosep® MF centrifugal device, or AcroPrep™ filter plates.
Syringe Filter and Spin Device SelectionThe table below outlines general guidelines to the appropriate filter size for different volumes of fluid.
|Volume to be Filtered||Filter Type||Typical Hold-up Volume|
|< 500 µL||Nanosep MF Device||< 2 µL|
|< 900 µL||AcroPrep 96 1 mL Filter Plate||< 18 µL/well|
|< 2 mL||4 mm Acrodisc Syringe Filter||< 10 µL|
|< 2 mL||AcroPrep 24 Filter Plate||< 50 µL/well|
|< 10 mL||13 mm Acrodisc Syringe Filter
|< 14 µL|
|< 10 mL||13 mm Acrodisc Syringe Filter||< 30 µL|
|< 125 mL||25 mm Acrodisc PSF Syringe Filter||< 200 µL|
Consider PrefiltrationFor difficult-to-filter samples, it is best to use a syringe filter with a glass fiber prefilter over the membrane. The Acrodisc PSF syringe filter with GxF multi-layered glass fiber prefilter is the best option for extremely particulate-laden samples. Our traditional Acrodisc syringe filters with GHP and Nylon membranes are also available with a single-layer glass fiber prefilter.
The Acrodisc PSF syringe filter has a serial glass fiber (GxF) prefilter to allow for maximum throughput and faster flow rates than standard glass fiber prefilter devices. The multi-layered prefilter, rated from > 40 to 1 µm, traps particulate, thereby extending filter life.