Sterile filters

Sterile filters can be used in a forward (syringe>filter>tube) and backward (tube>filter>syringe) direction to remove microorganisms and particles depending on the chosen pore size. Commonly used filters include Millipore's single use Millex filters.

Pore size

• 0.10 µm - 100 nm
• 0.22 µm - 220 nm
• 0.45 µm - 450 nm

Size comparison

• 0.01-0.3 µm - 10-300 nm viruses
• 0.4-0.6 µm - 400-600 nm Lactobacillus brevi/Listeria innocua width [1]
• 0.7-1.2 µm - 700-1200 nm E. coli width [2]
• 4 - 6 µm - 4000-6000 nm S. cerevisiae diameter [3])

Comments

In my hands, I lose about 0.4ml in a 33mm Millex 0.22µm filter. If I squeeze through 5ml of water, the initial volume recovered is about 4.5ml. With three air washed, I can recover 4.6ml in total 0.4ml remains stuck in the filter (dead volume). --Jakob Suckale 06:35, 25 February 2009 (EST)

Links

• Millex® 33 mm Filter Units with Durapore® PVDF Membrane - description and test
• Effect of pore size on microbrial recovery - Millipore