Filters for Prefiltration and Contamination Analysis

Millipore fibrous disc filters are available in a wide range of flow rates and throughput capacities. Glass fiber filters are available with or without binder resins and can be sterilized by EO, gamma, or autoclave (121 °C at 1 bar).

Glass Fiber Filters with Binder Resin

Millipore filters with binder resin have superior wet strength and are excellent for qualitative analysis and prefiltration, especially for heavily contaminated liquids. They are also widely used for clarification of aqueous solutions.

Type AP15

• Lowest dirt-holding capacity
  
• Recommended prefilter for 0.2 to 0.6 µm filters

Type AP20

• Lower retention, higher dirt-holding capacity than AP15 filters
  
• Recommended prefilter for 0.8 to 8.0 µm filters
  
• Use upstream to protect type AP15 filters

Type AP25

• Added thickness yields same retention and greater dirt-holding capacity as AP20
  
• Recommended prefilter for 0.9 to 8 µm filters, especially for proteinaceous and heavily contaminated liquids
  
• Use upstream to protect type AP15 filters

Glass Fiber Filters without Binder Resin

The filters without binder resin retain their structural integrity without weight loss when heated up to 500 °C and can therefore be used in gravimetric analysis as well as for the filtration of hot gases.

Type APFA

• Retains fine particles with good efficiency, even at high flow rates
  
• Recommended for monitoring wastewater and collecting suspended particles in gases (e.g., fumes from chimneys)
  
• Use in biochemical applications (e.g., collection of cells and filtration of protein or nucleic acid precipitates)

Type APFB

• Higher mechanical strength when wet and greater loading capacity than type APFA filters
  
• Use for liquid clarification, quantification of solids in suspensions of fine particles, and scintillation counting

Type APFC

• Greater retention, especially for fine particulate and microorganism removal than type APFA filters
  
• Use for determining total suspended solids in drinking water
  
• Use for filtering proteins or nucleic acid TCA precipitates and for collecting cells and microorganisms

Type APFD

• Thick filter with high flow and low retention
  
• Use for clarifying suspensions containing particulates > 1.0 µm

Type APFF

• Use for filtering extremely fine precipitates such as protein, nucleic acids, or serum precipitates
  
• Recommended for USEPA method 1311 for TCLP analysis

Type AP40

• Recommended for Standard Methods Total Suspended Solids 2540D
  
• Recommended for USEPA method 1311 for TCLP analysis
  
• Maintains structural integrity without weight loss when ignited to 550 °C (1022 °F) after sample filtration
  
• Recommended for determining volatile suspended matter in wastewater and industrial effluents

Quartz Fiber Filters (Type AQFA)

Made of very pure quartz fibers with no glass fibers or binders. The pure quartz composition prevents the filters from reacting with acidic gases, unlike glass fiber filters that can react and cause false readings. This makes quartz filters well suited for measuring heavy metal concentrations and small amounts of particles (such as the USEPA PM 10 ambient air monitoring method). The filters also exhibit good weight and form
stability.