Microbiology Guide: Membrane Filtration (MF) Method

Document ID

Document ID TE8836

Version

Version 1.0

Status

Status Published

Published Date

Published Date 06/06/2018
Question
Microbiology Guide: Membrane Filtration (MF) Method
Summary
Microbiology Guide: Media and Equipment Selection; Membrane Filtration (MF) Method
Answer
From: Microbiology Guide: Media and Equipment Selection


Dilution and Interpretation
  • Optimal colony number: 20-80 colonies per agar plate
 
  • Procedure
    • Wash hands or wear gloves if necessary.
    • Open a bottle of sterile Buffered Dilution Water.
    • Invert the sample container in a waist-to-ear motion, approximately 25 times (for 30 seconds).
    • Use a sterile pipet to add 11 mL of sample into the dilution water bottle.
    • Put the cap on the dilution water bottle. Invert the bottle in a waist-to-ear motion, approximately 25 times (for 30 seconds). This is a 10-fold or 10x dilution (sample is diluted by a factor of 10).
    • Add 11 mL of the 10x dilution to another dilution bottle and mix well (100x dilution).
    • Add 11 mL of the 100x dilution to a third bottle and mix well (1000x dilution).
    • Continue to make dilutions until the necessary dilution level has been reached
  • Dilution Series Steps
    • 10-mL sample: Transfer 11 mL of sample into 99 mL of sterile Buffered Dilution Water.
    • 1-mL sample: Transfer 11 mL of the 10-mL dilution from the previous step into 99 mL of sterile Buffered Dilution Water.
    • 0.1-mL sample: Transfer 11 mL of the 1-mL dilution from the previous step  into 99 mL of sterile Buffered Dilution Water.
    • 0.01-mL sample: Transfer 11 mL of the 0.1-mL dilution from the previous step  into 99 mL of sterile Buffered Dilution Water.
    • 0.001-mL sample: Transfer 11 mL of the 0.01-mL dilution from the previous step into 99 mL of sterile Buffered Dilution Water.
    • 0.0001-mL sample: Transfer 11 mL of the 0.001-mL dilution from the previous step into 99 mL of sterile Buffered Dilution Water.
 
  • Calculation
    • Calculation (single filter test) Use the following equation to calculate the result from a single membrane filter. Note that “mL sample” in the equation refers to the actual sample volume and not the diluted volume.

*If growth covers the entire filtration area of the membrane, or a portion of it, and Colonies are not discrete, report results as “Confluent Growth With or Without Coliforms.”

Filtration Step
  • Disposable Field Filtration Assemblies
    • Filter, Analytical Unit, Type A  (Catalog Number/Order Code 2656600)
 
  • Filtration flask / Filter holder Options
    • Filter holder Options
      • Filter, holder, magnetic, 47mm  (Catalog Number/Order Code 1352900)
      • Polysulfone filter holder (Catalog Number/Order Code 2254400)
      • Filter holder, glass (Catalog Number/Order Code 234000)
    • Filter flask options
      • Filtration flask 500mL 54649 Stopper 7 (Catalog Number/Order Code 1480407)
      • Filtration flask 1000mL 54653 Stopper 8 (Catalog Number/Order Code 148047)
    • Hand pumps
      • Pump, vacuum, with vacuum guage (Catalog Number/Order Code 2094100)
      • Pump, vacuum (Catalog Number/Order Code 1428300)
 
  • Filtration Manifold
    • Single
      • Pall Microfunnel Manifold (Catalog Number/Order Code 2831600)
        • Complete filter assemblies
          • Pall Vacuum filter microfunnel LP (Catalog Number/Order Code 2831500)
          • Pall Filter funnel, micro II (Catalog Number/Order Code 2619000)
      • Millipore Filter Assembly, portable complete (Catalog Number/Order Code 2586200)
        • Complete filter assemblies
          • Microfil funnel & filter (Catalog Number/Order Code 2586300)
          • Microfil V filtration device (Catalog Number/Order Code 2508900)
    • Multiple Place
      • Pall Filter Manifolds
        • Aluminum filter funnel manifold (Catalog Number/Order Code 2486100)
        • Polyurethane filter funnel manifold (Catalog Number/Order Code 2486150)
        • Complete filter assemblies
          • Pall Vacuum filter microfunnel LP (Catalog Number/Order Code 2831500)
          • Pall Filter funnel, micro II (Catalog Number/Order Code 2619000)
      • Sartorius Bombisart System
        • Sartorius Combisart 6 place system (Catalog Number/Order Code 2519702)
        • Sartorius Combisart 3 place system (Catalog Number/Order Code 2519701)
        • Complete filter assemblies
          • Sartorius biosart 100 monitor Bulk Sterile packed(Catalog Number/Order Code 2521100)
          • Sartorius biosart 100 monitor Sterile indivdually packed(Catalog Number/Order Code 2521101)
          • Sartorius biosart 100 monitor Sterile packed(Catalog Number/Order Code 2521102)
 
  • Filter Options
    • PALL GN-6 47mm, 0.45um, individually packaged, gridded, sterile
      • pk 200 (Catalog Number/Order Code 1353001 )
      • pk 1000  (Catalog Number/Order Code 1353002 )
    • Millipore S-Pak type HA membrane filters, 47mm, 0.45um, individually packaged, sterile
      • Pk 600 (Catalog Number/Order Code 2936500)
    • Millipore EZ Pak System filters
      • Millipore EZ Pak membranes, 47mm, 0.45um, gridded, pk 600 (Catalog Number/Order Code 2916800)
      • Millipore EZ Pak Dispenser (Catalog Number/Order Code 2916700)
Petri Dish Step
  • Petri dish
    • 15 x 100mm pk 600 (Catalog Number/Order Code 2178900)
    • 15 x 100mm pk 20  (Catalog Number/Order Code 2178901)
    • 9 x 50mm pk 100  (Catalog Number/Order Code 1485299)
    • 9 x 50mm pk 500  (Catalog Number/Order Code 1485200)
 
  • Petri dish with Pad
    • Pall Petri dish with pad pk 100 (Catalog Number/Order Code 1471799) *recommended
    • Millipore petri dish with pad pk 150 (Catalog Number/Order Code 2936300)
Attachments
Internal Notes