|PTFE Membrane Filters - For filtering acids, bases, or solvents, as well as gases|
|What is the blue separation paper between my filters?||It is a parchmentalized paper specially formulated for Millipore Corporation.|
|What are the dimensions and width of the grids on the Millipore 47mm gridded membranes?||The grids are 3.08mm x 3.08mm square. A grid line is 44um in width and there is are average of 169 gridded squares per filter. Please note however that the actual filtration area and therefore the total number of squares in that area is dependent on the filter holder. For filter holders with 9.6sq.cm of filtration area there are 100 squares available. For filter holders with 13.8 sq.cm of filtration area the number of available grids are approximately 140.|
|Which side of the membrane should I use, the shiny or dull side?||Most researchers may not even notice that there is a "sidedness" to filters, and, for most applications, orientation will not affect filter performance. However, membranes do have a slightly asymmetric pore structure: the shiny side of the membrane is the "tighter" side. In some applications, you can take advantage of this difference by selecting a specific filter orientation. ultrafiltration membranes should always be used shiny side up, regardless of application for drop dialysis ( a buffer exchange technique in which a few drops of DNA or protein are placed in a 0.05 or 0.025 um filter and floated on a buffer solution), apply the sample to the shiny side of the filter and float the filter dull side to the buffer. This measure will enhance buffer exchange and discourage sample loss. The Millipore Express and Express Plus membranees are also sided - these membranes should be used shiny side facing down.|
|What is the difference between pore size and pore size distribution?||Whereas pore size is a measure of the diameter of the largest pore, pore size distribution is a measure of the range of pore sizes. The range of pore sizes can be normally distributed, and the spread can be quite narrow (e.g. the ratio of largest to smallest may be less than 2). On the other hand, pore size distribution can be very heterogeneous. In the case of large spreads and heterogeneity, the pore size will be far less predictive of flow rate (either filtration or capillary) than it will be for a membrane with a narrow pore size distribution. It is important to note that the pore size corresponding to the bubble point is not at the middle of the distribution, but is the largest pore.|
|Can Fluoropore or Mitex PTFE membranes be gamma sterilized?||No. This polymer breaks down when exposed to gamma irradiation. These membranes can be sterilized with EtO or by autoclaving. The membrane can be sanitized via short term (10 minute) soak in 70% ethanol.|
|What are the protein binding characteristics of the Fluoropore membrane?||When wet out with alcohol, the hydrophobic Fluoropore (PTFE) membrane is high protein binding. The hydrophilic LCR (PTFE) membrane is low protein binding.|
|How do I tell the membrane from the separator?||The blue paper is the separator.|
|Can I autoclave my filters?||Millipore's MF, Durapore, Fluoropore and Mitex filters are all autoclavable. Standard conditions of 121-126C for 20-30 min generally work quite well. However, the filters should be autoclaved on a "slow exhaust (liquid) cycle. Because Fluoropore membranes have a polyethylene backing they will be slightly wrinkled after autoclaving.|
|When using Fluoropore membranes, what side should be facing up to my solution?||If you are performing particle analysis on the membrane surface, you must orient the filter dull side up (facing the solution to be filtered). Otherwise, for general filtration purposes, you may orient the membrane in either direction. In some instances, it has been found that orienting the shiny (laminated backing) side up, a better seal is formed in the filter holder.|
Fluoropore Membrane Filters
Fluoropore membrane is a hydrophobic PTFE membrane bonded to a high density polyethylene support (FHUP has no backing).Fluoropore membranes provide broad chemical compatibility.
Mitex Membrane Filters
Mitex is an unsupported hydrophobic PTFE membrane. It can be used under extreme chemical or temperature conditions that other membranes cannot withstand (up to 260 °C).
LCR Membrane Filters
LCR is an unsupported hydrophilic PTFE membrane compatible with all commonly used HPLC solvents. It can be used to filter aqueous fluids without prior wetting. Available in syringe filters.
Omnipore Membrane Filters
Omnipore membrane is hydrophilic PTFE compatible with virtually all solvents, acids, and alkaline solutions (for HPLC solvent filtration, use LCR membrane).
* Some PTFE membrane containing products may be limited to specific applications. Those products will contain an inserts specifying the limits of use.
Sterilization: by autoclave (121 °C at 1 bar) or EO
Bacterial endotoxins: 0.5 EU/mL
Gravimetric extractables: < 0.5%
|Applications||Filter Code1||Pore Size
|Air Flow Rate
|Fluoropore Membranes (hydrophobic)|
|Clarifying acids, bases, and solvents, air monitoring, filtering or venting gases, UV spectroscopy||FGLP||0.22||1.0||150||24||5||130||85|
|Mitex Membranes (hydrophobic)|
|Clarifying acids, bases, and cryogenic fluids, clarifying propellants, analyzing hydraulic fluids, isolating RNA||LSW||5||0.06||170||70||9||260||60|
|LCR Membranes (hydrophilic)|
|Clarifying acids, bases, cryogenic fluids, and dilute protein solutions, clarifying propellants, analyzing hydraulic fluids, isolating RNA||FHLC||0.45||NA||140 (maximum)||70||8||130||80|
|Omnipore Membranes (hydrophilic)|
|Clarifying acids, alkaline solutions, and virtually all solvents||JVWP||0.1||23.6||30||100|
|1Corresponds to first 4 digits of catalogue number
2Bubble point of Fluoropore measured with methanol, Mitex
3Fluoropore with methanol; Mitex and LCR with water. For Omnipore 100 mL water, 20°C, 47 mm disk, 8.97" Hg vacuum
4Air flow rates for Mitex are for the number of seconds for 100 cm3 of air to pass through 1 in2 of membrane (Gurley test)