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Cellulose membranes

Whatman offers the following cellulose membranes:
   (a) Pure cellulose nitrate
   (b) Pure cellulose acetate
   (c) Mixed esters of cellulose nitrate and cellulose acetate

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Regenerated_cellulose_membranes

Cellulose acetate membranes
Whatman cellulose acetate membranes are made from pure cellulose acetate making them ideal for biological and clinical analysis, sterility tests and scintillation measurements.

 

Cellulose membranes
> Cellulose acetate membrane (Type ST 68, 0.8µm)

Cellulose acetate membrane filters exhibit very low protein binding capacity. They are hydrophilic making them suitable for aqueous and alcoholic media. The cellulose acetate membranes have improved solvent resistance, particularly to low molecular weight alcohols and increased heat resistance. With high physical strength, the membrane filters can be used up to 180ºC; suitable for hot gases and can be sterilised by all methods without sacrificing the integrity of the membrane.
 

 

Typical Properties - Cellulose Acetate Membranes
  Thickness
(µm) 		Water flow rate
p = 0.9 bar
mL/min/cm2		 Air flow rate
p = 3 mbar
mL/min/cm2		 Bubble point
(bar)
OE 66 115 20 — 3.7
OE 67 115 40 25 2.7
ST 68 140 170 50 1.5
ST 69 140 300 90 0.9

 

Ordering Information - Cellulose Acetate Membranes        
Diameter (mm) Pore Size (µm) Catalogue Number Sterile Quantity/Pack
WCA
25 0.2 7000-0002 No 100
25 0.45 7000-0002 No 100
47 0.45 7000-0004 No 100
OE 66
25 0.2 10 404 106 No 100
47 0.2 10 404 112 No 100
47 0.2 10 404 170 Yes 100
50 0.2 10 404 114 No 100
110 0.2 10 404 126 No 50
142 0.2 10 404 131 No 25
293 0.2 10 404 139 No 25
300 x 600 0.2 10 404 180 No 5
OE 67
13 0.45 10 404 001 No 100
25 0.45 10 404 006 No 100
47 0.45 10 404 012 No 100
50 0.45 10 404 014 No 100
85 0.45 10 404 044 No 50
100 0.45 10 404 021 No 50
110 0.45 10 404 026 No 50
142 0.45 10 404 031 No 25
OE 67/A
142 0.45 10 404 331 No 25
ST 68
25 0.8 10 403 106 No 100
47 0.8 10 403 112 No 100
50 0.8 10 403 114 No 100
ST 69
47 1.2 10 403 012 No 100
50 1.2 10 403 014 No 100
 

 

 

 

Cellulose membranes
> Cellulose nitrate membrane
Cellulose nitrate membranes
  

 

Recommended for the majority of routine applications, this grade is manufactured under strictly controlled cleanroom conditions. Usually, it can directly replace the general purpose membrane filters of other manufacturers without requiring any significant change of technique. The user will benefit from the performance improvements which are now available in Whatman membrane filters.

Higher Strength and Flexibility
Most membranes are inherently brittle and difficult to handle; it is not uncommon for filters to be damaged during loading into holders or while in use. Whatman Cellulose Nitrate membrane filters have a noticeably improved flexibility and are made to tolerate abuse during handling, loading and autoclaving without sacrificing integrity. These membranes are among the strongest of their type available, as measured and compared by burst pressure tests.

Low Extractable Levels
The level of extractables in membrane filters has become more important with advances in filtration or adsorption techniques. In particular, pharmaceutical, immunological, biomedical tissue culture and trace analysis applications can be adversely affected by high extractable levels. Whatman Cellulose Nitrate membrane filters have a low level of extractables generally below that of other membranes of a similar type.

Narrow Pore Size Distribution
One of the major features of Whatman membrane filters is the narrow distribution of pore sizes. The rated pore size of these membranes is closely controlled due to the advanced manufacturing and control system. Additionally, the batch-to-batch variation is minimised providing more consistent laboratory results.

Increased Temperature Stability
Membrane filters are normally autoclaved at 121°C without loss of integrity. Cellulose nitrate membranes are supplied as circles, sheets or reels.

Reduced Shrinkage
Excessive shrinkage can cause problems during autoclaving and is often the cause of membranes tearing in their holders after autoclaving. It may also cause a reduction in flow rate and total throughput. Whatman membranes exhibit a low shrinkage during autoclaving.

Cellulose Nitrate Filter Types
 

White Plain Filters. This is the standard membrane filter for the majority of laboratory applications involving particles and cells in the range of 0.1µm to 5.0µm. The residue after filtration is found to be almost completely on the surface of the membrane and allows physical recovery of deposits and microscopic examination.

Cellulose Nitrate Membranes for Nucleic Acid and Protein Analysis In 1975 E. M. Southern developed the technique for transferring DNA from agarose gels onto a nitrocellulose membrane. The technique was named Southern Blotting after its inventor. Subsequently, techniques for protein transfer and RNA transfer were also developed. In association with the blotting technique, substantial quantities of good quality chromatography paper are required and 3MM Chr has become the leading choice throughout the world.

Features and Benefits
 

  • Narrow pore size distribution for improved surface capture and analysis
  • Low levels of extractables to ensure sample integrity

Applications

  • Sample preparation
  • Microbiological studies
  • Filtration of aqueous solutions

 

Typical Data
  Cellulose Nitrate
Thickness 125 µm
Burst Strength >2 psi
Weight 3.6–5.5 mg/cm2
Maximum Service Temperature 80ºC
Porosity 66–84%
Steam Autoclavable Yes
Hydrophilic Yes

 

 

Typical Applications - Cellulose Nitrate Membranes
Field of Application Pore Size (µm)
General
Microfiltration 0.1
Ultracleaning 0.1
Sterilizing 0.2
Bulk Bacterial Removal 0.45
Analytical Precipitates 0.65
Clarifying Filtration 1
Particle Removal 5
Water Microbiology and Analysis
Bacterial Colony Count 0.45 (grid)
Sediment Analysis 0.45
Suspended Particles 5
Air Pollution Monitoring
Asbestos Monitoring (NIOSH) 0.8
Food and Beverage QC
E. coli and Coliforms 0.45 (grid)
Total Bacteria Count 0.2
Tissue Culture
Mycoplasma Removal 0.1
Sterile Filtration 0.2

 

Ordering Information - Cellulose nitrate membranes
Diameter (mm) Pore Size (µm) Catalogue Number Type1 Sterile2 Protein Binding Quantity/ Pack
WCN
13 0.2 7182-001 Plain No High 100
13 0.45 7184-001 Plain No High 100
25 0.2 7182-002 Plain No High 100
25 0.3 7193-002 Plain No High 100
25 0.1 7181-002 Plain No High 100
25 0.45 7184-002 Plain No High 100
25 0.65 7186-002 Plain No High 100
25 0.8 7188-002 Plain No High 100
25 1.0 7190-002 Plain No High 100
25 3.0 7193-002 Plain No High 100
25 5.0 7195-002 Plain No High 100
37 0.45 7184-003 Plain No High 100
37 0.8 7188-003 Plain No High 100
47 0.1 7181-004 Plain No High 100
47 0.2 7182-004 Plain No High 100
47 0.45 7141-004 Gridded No High 100
47 0.45 7141-104 Gridded Yes High 100
47 0.45 7141-114* Gridded Yes High 100
47 0.45 7141-204** Gridded Yes Medium 100
47 0.45 7141-124 Gridded Yes Medium 200
47 0.45 7141-154*** Gridded Yes High 1000
47 0.45 7184-004 Plain No High 100
47 0.65 7186-004 Plain No High 100
47 0.8 7188-004 Plain No High 100
47 1.0 7190-004 Plain No High 100
47 3.0 7193-004 Plain No High 100
47 5.0 7195-004 Plain No High 100
82 0.45 7184-008 Plain No High 25
90 0.2 7182-009 Plain No High 25
90 0.45 7184-009 Plain No High 25
90 0.8 7188-009 Plain No High 25
90 1.0 7190-009 Plain No High 25
90 5.0 7195-009 Plain No High 25
142 0.2 7182-014 Plain No High 25
142 0.45 7184-014 Plain No High 25
293 0.45 7184-029 Plain No High 25
AE 98
25 5.0 10 400 206 Plain No High 100
47 5.0 10 400 212 Plain No High 100
50 5.0 10 400 214 Plain No High 100
AE 99
25 8.0 10 400 106 Plain No High 100
37 8.0 10 400 109 Plain No High 100
47 8.0 10 400 112 Plain No High 100
50 8.0 10 400 114 Plain No High 100
50 8.0 10 405 079 Plain † No High 100
150 8.0 10 400 132 Plain No High 25
AE 100
47 12.0 10 400 012 Plain No High 100
50 12.0 10 400 014 Plain No High 100
NC 10
47 0.1 10 402 012 Plain No High 100
50 0.1 10 402 014 Plain No High 100
NC 20
25 0.2 10 401 306 Plain No High 100
47 0.2 10 401 312 Plain No High 100
50 0.2 10 401 314 Plain No High 100
142 0.2 10 401 331 Plain No High 25
NC 45
24 0.45 10 401 104 Plain No High 100
25 0.45 10 401 106 Plain No High 100
47 0.45 10 401 112 Plain No High 100
47 0.45 10 401 170 Plain Yes High 100
50 0.45 10 401 114 Plain No High 100
90 0.45 10 401 118 Plain No High 50
100 0.45 10 401 121 Plain No High 50
110 0.45 10 401 126 Plain No High 50
142 0.2 10 401 131 Plain No High 25
1The ink used in the gridded filters is non-toxic and is free of bacterial growth inhibitors. Each line is spaced at 3.1 mm intervals.
2Sterile membranes are packed individually with an absorbent pad. Sterilized using ethylene oxide gas.
† With hydrophobic rim
* Packed without pad.
** Autoclave pack contains 10 sealed envelopes. Each envelope contains 10 filters with 10 pads.
*** 1000/box without absorbent pad.
 

 

Membra-Fil® mixed ester membranes
Features and Benefits

 

  • The membrane offers a high degree of internal surface area for greater adsorption of product
  • Higher dirt loading capacity
  • Low protein binding characteristics
  • Biologically inert with good thermal stability.
  • No surfactants to contaminate samples
  • Uniform microporous structure of membrane gives high flow rates
  • Thermally stable
  • Made with 80:20 ratio of cellulose nitrate to cellulose acetate

Applications
The membrane is particularly effective in applications requiring higher flow rates and larger volume filtration including clarification or sterilisation of aqueous solutions, particulate analysis and removal, air monitoring and microbial analysis. Other applications include:

  • Clarification or sterilisation of aqueous solutions.
  • Cytology
  • Air monitoring
  • HPLC samples (aqueous)
  • Virus concentration
  • Particulate analysis
  • Biological assays
  • Food microbiology including enumeration of E. Coli in foods

 

Ordering Information - Membra-Fil® Membranes (Mixed Cellulose Esters)
Diameter (mm) Pore Size (µm) Catalogue Number Quantity/Pack
13 0.45 140418 100
13 5 140413 100
25 0.22 140628 100
25 0.45 140618 100
25 1.2 140627 100
25 5 140613 100
47 0.22 141128 100
47 0.45 141118 100
47 0.65 141119 100
47 0.8 141109 100
47 1.2 141127 100
47 3 141112 100
47 5 141113 100
90 0.45 141718 100
142 0.22 142128 25
142 0.45 142118 25
142 0.8 142109 25

 

 

Cellulose membranes
> Whatman mixed cellulose ester membranes

Whatman mixed cellulose ester membranes

Whatman mixed cellulose ester membranes are composed of cellulose acetate (~20%) and cellulose nitrate (~80%). These membranes are characterised by a smoother and more uniform surface than pure nitrocellulose filters. Also, the colour contrast provided by the filter surface facilitates particle detection and minimises eye fatigue.

Eased Counting Process
In microbiological colony counting procedures, the colour contrast between the surface and the colonies facilitates the counting process.

Plain or Gridded
Many microbiological techniques include colony counting after incubation as the standard method of quantification. Whatman gridded filters have clearly defined grid lines spaced at 3.1mm intervals. The special ink used is non-toxic and completely free from bacterial growth inhibitors.

Whatman black mixed cellulose esters are available plain for automatic colony counting applications, as well as gridded to assist in manual counting procedures. Black membranes provide contrast between residue or cell colours and the filter without having to counter stain the membrane.

Sterile Filters
For those laboratories preferring to use membranes sterilised by autoclaving for microbiological work, Whatman provides black gridded membranes in packs with pads ready for laboratory autoclaving.

Features and Benefits
  • Sterile options available for critical applications
  • Excellent contrast for easier particle detection
  • Grids are non-toxic and do not inhibit bacterial growth, ensuring sample integrity
  • Autoclavable for repeated use
  • Black plain and black gridded membranes have 80:20 ratio of CN:CA
Applications
  • Bacteriological studies
  • Particle counting from liquids and aerosols
  • Yeasts and moulds

 

Typical Data - Mixed Cellulose Ester Membranes
Burst Strength >10 psi
Weight 4.3–5.0 mg/cm2
Maximum Service Temperature 130°C
Porosity 74–77%
Steam Autoclavable Yes
Solvent Resistancy Medium
Protein Binding1 Medium
1 WME white gridded type: high protein binding

 

Product Selection
  Thickness
(µm)		 Water flow rate
p = 0.9 bar
ml/min/cm2		 Air flow rate
p = 3 mbar
ml/min/cm2		 Bubble point
(bar)
WME 140 — — —
ME 24 135 25 — 3.7
ME 25 135 45 25 2.5
ME 26 135 110 45 1.5
ME 27 140 170 80 1.3
ME 28 140 240 100 0.8
ME 29 150 400 140 0.7

 

Ordering Information - Whatman Mixed Cellulose Ester Membranes
Diameter (mm) Pore Size (µm) Catalogue Number Type Sterile Quantity/Pack
WME
47 0.45 7153-004 Black Gridded No 100
47 0.45 7153-104 Black Gridded Yes 100
47 0.2 7187-114 White Gridded Yes 100
ME 24
25 0.2 10 401 706 Plain No 100
47 0.2 10 401 712 Plain No 100
47 0.2 10 401 770 Plain No 100
50 0.2 10 401 714 Plain No 100
50 0.2 10 401 772 Plain Yes 100
110 0.2 10 401 726 Plain No 50
142 0.2 10 401 731 Plain No 25
ME 25
25 0.45 10 401 606 Plain No 100
47 0.45 10 401 612 Plain No 100
47 0.45 10 401 670 Plain Yes 100
50 0.45 10 401 614 Plain No 100
50 * 0.45 10 401 662 Plain No 100
50 0.45 10 401 672 Plain Yes 100
90 0.45 10 401 618 Plain No 50
100 0.45 10 401 621 Plain No 50
110 0.45 10 401 626 Plain No 50
142 0.45 10 401 631 Plain No 25
ME 26
47 0.6 10 401 512 Plain No 100
50 0.6 10 401 514 Plain No 100
ME 27
25 0.8 10 400 906 Plain No 100
37 0.8 10 400 909 Plain No 100
47 0.8 10 400 912 Plain No 100
47 0.8 10 400 970 Plain Yes 100
50 0.8 10 400 914 Plain No 100
100 0.8 10 400 921 Plain No 50
ME 28
25 1.2 10 400 806 Plain No 100
47 1.2 10 400 812 Plain No 100
50 1.2 10 400 814 Plain No 100
ME 29
25 3.0 10 400 706 Plain No 100
47 3.0 10 400 712 Plain No 100
50 3.0 10 400 714 Plain No 100
50 3.0 10 400 772 Plain Yes 100
* Without interleaving papers
 

 

 

 

Cellulose membranes
> Regenerated cellulose membrane (Type RE 55, 0.45μm) Electron micrograph (magnification 1000x)
Regenerated cellulose membranes
Whatman regenerated cellulose membranes are made of pure cellulose, without any wetting agents. 

Features and Benefits

  • Spontaneously wetting, very good wet strength
  • Extremely chemically resistant; suitable for aqueous and organic media
  • Hydrophilic
  • Mechanically stable
  • Can be used up to 180°C
  • Sterilizable by all methods
  • Pore sizes between 0.2 µm and 1 µm
  • Suitable for use as sterile filter to ASTM D 3862-80

 

Typical Data - Regenerated Cellulose
  Thickness
(µm)		 Water flow rate
p = 0.9 bar
ml/min/cm2
 		 Air flow rate
p = 3 mbar
ml/min/cm2
 		 Bubble point
(bar)
RC 58 75 20 — 3.7
RC 55 75 35 — 3.5
RC 60 75 240 75 0.8

 

Ordering Information - Regenerated Cellulose
Diameter (mm) Pore Size (µm) Catalogue Number Sterile Quantity/Pack
RC 58
47 0.2 10 410 312 No 100
50 0.2 10 410 314 No 100
100 0.2 10 410 319 No 25
RC 55
25 0.45 10 410 206 No 100
47 0.45 10 410 212 No 100
50 0.45 10 410 214 No 100
100 0.45 10 410 219 No 25
110 0.45 10 410 224 No 25
142 0.45 10 410 229 No 25
RC 60
47 1.0 10 410 012 No 100
50 1.0 10 410 014 No 100
 

 

 

 

 

For more information :: Bioxys and Gentaur BVBA :: Av. de l'Armée 68 B4 :: BE-1040 BELGIUM

Email: info@gentaur.com
 

International 

+32 (0) 16 58 90 45

+32 (0) 16 50 90 45

France

01 43 25 01 50

01 43 25 01 60

Italy

02 36 00 65 93

02 36 00 65 94

Germany

0241 6085 13140

0241 6085 33033
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Last modified: feb-07