MicroFunnel™ Filter Funnels Performance Guide
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Introduction
Standard Product Features
Pall Life Sciences incorporates the high standards of design that you have come to expect from the premier disposable filter funnel manufacturer. Users will benefit from these standard features:
- Each lot is provided with a product certification to add assurance of reliable results.
- Individually labeled, bagged, and disposable filter units prevent cross-contamination of samples and allow for lot traceability.
- Disposable design eliminates the cleaning and sterilization required with reusable funnels.
- Preassembled and gamma irradiated to eliminate the potential for toxic residuals associated with EtO sterilization.
- Integral unit and membrane ensure accurate results with high bacterial recoveries and no grid-line inhibition.
- Easy removal of membrane from base enables simple transfer of membrane for culturing.
- Unique squeeze separation allows easy removal of cylinder from the base without disruption of the membrane and reduces operator fatigue.
- 100 mL and 300 mL funnel graduations are clearly marked on the cylinder for higher visibility and reading from any position.
- Specially designed base allows the funnel to be placed directly onto most filter manifolds without the need for a separate stopper or adapter.
- Constructed of inert polypropylene for improved chemical compatibility to eliminate the potential extractables.
- PN 4810 has an additional lid Petri dish to which the membrane can be transferred after filtration.
Summary of Suitability for the Membrane Filter (MF) Technique
The MF Technique is commonly accepted throughout the world for the analysis of microbial contamination in fluid samples. Using the technique, microorganisms are captured on the membrane surface and grown into countable colonies. Pall Life Sciences has designed the MicroFunnel filter funnel to simplify this testing. For a complete protocol, see Pall Life Sciences PN 32860, “Protocol: Membrane Filter Technique.”
MicroFunnel filter funnels for microbiological analysis are in accordance with the Membrane Filtration procedures referenced in Standard Methods for the Examination of Water and Wastewater, 21st edition, and the U.S. Environmental Protection Agency’s Microbiological Methods for Monitoring the Environment, 600/8-78-017. MicroFunnel filter funnels also meet the USP-24 requirements for products used for the MF Technique.
Representative samples were tested and met the following parameters:
- Recovery testing has shown that the grid lines do not enhance or inhibit growth of organisms.
- The sterilization process did not enhance or inhibit subsequent growth of organisms.
- Recovery of test organisms indicates that there is no influence on growth due to chemical extractables.
MicroFunnel filter funnels are manufactured according to current Good Manufacturing Practices (cGMP). Pall Corporation’s Ann Arbor facility is certified for ISO 9001.
Each lot is certified by Pall Corporation for compliance with established specifications before release, and each box includes a product information insert and a product certification sheet.
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Specifications
GN-6 Metricel Membrane: A 0.45 µm mixed cellulose ester membrane ideal for use in most applications.
Supor Membrane: A 0.2 or 0.45 µm polyethersulfone membrane ideal for its low binding characteristics and superior retention of small organisms such as Pseudomonas sp.
Metricel Black Membrane: A 0.45 or 0.8 µm modified polyethersulfone membrane ideal for yeast and mold analysis or providing good contrast for light colored colonies.
Materials of Construction
Filter Media:
PN 4800, 4801, 4804, 4810, 4815, 4826: GN-6 Metricel membrane (mixed cellulose esters)
PN 4803, 4806, 4818, 4828, 4852: Supor membrane (hydrophilic polyethersulfone)
PN 4805, 4817, 4819, 4827: Metricel Black membrane (hydrophilic modified polyethersulfone)
Support Pad: Cellulose
Cylinder, Base, Lid Petri Dish Base: Polypropylene
Cover: Polystyrene
Plug: Polyethylene
Funnel Adapter: Polyethylene (not autoclavable)
Effective Filtration Area
13.46 cm2
Maximum Vacuum
635 mm Hg (25 in. Hg)
Sterilization
Individually bagged and gamma irradiated
Dimensions
100 mL Funnels
Height:
8.1 cm (3.2 in.) with Petri dish lid
7.6 cm (3.0 in.) with cover
Diameter:
6.4 cm (2.5 in.) with Petri dish lid
6.1 cm (2.4 in.) with cover
300 mL Funnel
Height:
9.1 cm (3.6 in.) with cover
Diameter:
8.8 cm (3.5 in.) with cover
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Microbial Recovery Testing
To determine if the membrane contained within the selected MicroFunnel filter funnel meets performance specifications for the recovery of suitable test organisms.
Procedure
- Determine the number of 100 mm density control plates required. A density control should be prepared for every 3 or 6 filtrations or a minimum of 5 plates per culture tested.
- Prepare a diluted test suspension from an 18 hour culture such that the final organism density will produce 50 to 70 cfu/mL.
- Aseptically open test MicroFunnel filter units and place onto manifold (10 units to be tested per organism).
- Dispense 8 to 10 mL of sterile saline into each test funnel, taking care that each filter surface is completely covered.
- Mix test suspension and pipette 1 mL into each test funnel.
- Filter the samples and rinse each test funnel with 2 consecutive 25 mL aliquots of sterile saline.
- Turn off the vacuum source.
- Culture five of the samples in the MicroFunnel filter funnel base by gently dispensing 2 mL of broth media over the surface sample and allowing it to be drawn into the pad. It may be necessary to momentarily apply vacuum just until the media is drawn through the membrane into the pad. Remove the test funnel from the manifold, plug the base, remove cover, and gently squeeze the top of the cylinder to disengage it from the base. Replace the cover onto the base of the MicroFunnel unit to convert into a Petri dish and discard the cylinder.
- Culture five of the samples by removing the membrane to another Petri dish. Gently squeeze the top of the cylinder to disengage it from the base. Transfer the membrane to an agar plate or broth-soaked pad in a Petri dish.
- Invert plates and incubate.
Test Results
- After incubation, examine the plates, count the colonies.
- Count density control plates. (Reference: Standard Methods for the Examination of Water and Wastewater, 21st edition, for counting and recording.)
Calculations
- Calculate the mean count for the test funnels.
- Calculate the standard deviation for each mean calculated. The coefficient of variation (CV) should be < 20%.
- CV = (o’ / X)(100)
- Calculate the percent recovery of the test funnels.
Test organism: Escherichia coli ATCC 11229
| PN 4800 is the representative product containing GN-6 Metricel membrane, 0.45 µm, white, gridded |
% recovery incubated in base using TSB broth, 5 test units |
% recovery incubated by removing to MF-Endo broth, 5 test units |
|---|---|---|
| Lot 1048L | 98% | 96% |
| Lot 1382L | 98% | 94% |
| Lot 1878L | 94% | 98% |
Test organism: Pseudomonas aeruginosa ATCC 14207
| PN 4803 is the representative product containing Supor membrane, 0.2 µm, white, gridded |
% recovery incubated in base using TSB broth, 5 test units |
% recovery incubated by removing to Pseudomonas broth, 5 test units |
|---|---|---|
| Lot 1305L | 97% | 91% |
| Lot 1443L | 97% | 97% |
| Lot 1179M | 96% | 101% |
Test organism: Saccharomyces cerevisiae ATCC 4117
| PN 4805 is the representative product containing Metricel Black membrane, 0.45 µm, gridded |
% recovery incubated in base using M-Green YM broth, 5 test units |
% recovery incubated by removing to M-Green YM broth, 5 test units |
|---|---|---|
| Lot 1197M | 96% | 101% |
| Lot 1626M | 100% | 97% |
| Lot 1933M | 100% | 103% |
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Liquid Flow Test
| Lot Number/Membrane Type | Diffusional Flow (cc/min) | Pressurized Leak Test |
| 1647J/GN-6 Metricel® 0.45 µm | <1.0 | Integral |
| 1647J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1647J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1647J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1647J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1943J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1943J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1943J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1943J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1943J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1998J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1998J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1998J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1998J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1998J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1443L/Supor® 0.2 µm | <1.0 | Integral |
| 1443L/Supor 0.2 µm | <1.0 | Integral |
| 1443L/Supor 0.2 µm | <1.0 | Integral |
| 1443L/Supor 0.2 µm | <1.0 | Integral |
| 1443L/Supor 0.2 µm | <1.0 | Integral |
| 1625M/Supor 0.2 µm | <1.0 | Integral |
| 1625M/Supor 0.2 µm | <1.0 | Integral |
| 1625M/Supor 0.2 µm | <1.0 | Integral |
| 1625M/Supor 0.2 µm | <1.0 | Integral |
| 1625M/Supor 0.2 µm | <1.0 | Integral |
| 1704L/Supor 0.2 µm | <1.0 | Integral |
| 1704L/Supor 0.2 µm | <1.0 | Integral |
| 1704L/Supor 0.2 µm | <1.0 | Integral |
| 1704L/Supor 0.2 µm | <1.0 | Integral |
| 1704L/Supor 0.2 µm | <1.0 | Integral |
| 1197M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1197M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1197M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1197M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1197M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1933M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1933M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1933M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1933M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1933M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1136N/Metricel Black 0.45 µm | <1.0 | Integral |
| 1136N/Metricel Black 0.45 µm | <1.0 | Integral |
| 1136N/Metricel Black 0.45 µm | <1.0 | Integral |
| 1136N/Metricel Black 0.45 µm | <1.0 | Integral |
| 1136N/Metricel Black 0.45 µm | <1.0 | Integral |
To characterize a typical flow rate for each membrane type.
Procedure
- Place test unit on the manifold.
- Pour 100 mL of 0.2 µm filtered water into test unit.
- Open valve on manifold (15 in. Hg) and simultaneously start the stop watch.
- Record the amount of time required for the water to flow through the membrane.
- Remove the test unit from the manifold and discard.
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Assembly Integrity
| Lot Number/Membrane Type | Diffusional Flow (cc/min) | Pressurized Leak Test |
| 1647J/GN-6 Metricel® 0.45 µm | <1.0 | Integral |
| 1647J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1647J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1647J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1647J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1943J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1943J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1943J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1943J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1943J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1998J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1998J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1998J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1998J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1998J/GN-6 Metricel 0.45 µm | <1.0 | Integral |
| 1443L/Supor® 0.2 µm | <1.0 | Integral |
| 1443L/Supor 0.2 µm | <1.0 | Integral |
| 1443L/Supor 0.2 µm | <1.0 | Integral |
| 1443L/Supor 0.2 µm | <1.0 | Integral |
| 1443L/Supor 0.2 µm | <1.0 | Integral |
| 1625M/Supor 0.2 µm | <1.0 | Integral |
| 1625M/Supor 0.2 µm | <1.0 | Integral |
| 1625M/Supor 0.2 µm | <1.0 | Integral |
| 1625M/Supor 0.2 µm | <1.0 | Integral |
| 1625M/Supor 0.2 µm | <1.0 | Integral |
| 1704L/Supor 0.2 µm | <1.0 | Integral |
| 1704L/Supor 0.2 µm | <1.0 | Integral |
| 1704L/Supor 0.2 µm | <1.0 | Integral |
| 1704L/Supor 0.2 µm | <1.0 | Integral |
| 1704L/Supor 0.2 µm | <1.0 | Integral |
| 1197M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1197M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1197M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1197M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1197M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1933M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1933M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1933M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1933M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1933M/Metricel Black 0.45 µm | <1.0 | Integral |
| 1136N/Metricel Black 0.45 µm | <1.0 | Integral |
| 1136N/Metricel Black 0.45 µm | <1.0 | Integral |
| 1136N/Metricel Black 0.45 µm | <1.0 | Integral |
| 1136N/Metricel Black 0.45 µm | <1.0 | Integral |
| 1136N/Metricel Black 0.45 µm | <1.0 | Integral |
Diffusional Flow Test
Purpose
To determine the integrity and seal of the membrane within the device.
Procedure
- Place test unit on the manifold.
- Wet test unit with 10% isopropyl alcohol in water.
- Attach proprietary design test cap.
- Apply (20 in. Hg) vacuum and allow unit to stabilize.
- Record diffusional flow value.
- Turn off vacuum, remove unit from manifold, and discard.
Pressurized Leak Test
Purpose
To ensure an integral seal between the funnel cylinder and base.
Procedure
- Place test unit on the manifold.
- Pour 100 mL of aqueous green dye solution into test unit.
- Attach proprietary design test cap.
- Pressurize to 0.5 psi and hold for 15 seconds.
- Observe for leakage and record results.
- Relieve pressure, remove funnel from manifold, and discard.
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