SPI Silver Membrane Filters

Enjoy the benefits of an electrically conductive substrate!

Scanning electron micrograph of
surface of SPI Silver Membrane
Filter. Horizontal distance is 60µm.

Chemical formula: Ag
CAS # 7440-22-4

Made from pure silver, SPI Silver Membranes can withstand extreme temperature, pressure and solvents without collapsing, tearing, curling, or dissolving. More than tough, they are very smooth, extremely thin (.002" thick/51µm), and uniformly porous; they are also reusable (cleaned by oxygen isotropic plasma etching, ignition procedures, or sometimes just by simply back-washing). The most convenient if not also the best way for the cleaning for reuse of silver membrane filters is with the use of the SPI Plasma Prep II unit. The silver membrane filters are available from pore sizes of 0.2 to 5痠. For smaller pore sizes, one would need to use the aluminum oxide membrane filters.

Actually, we can offer quite a bit of other information about the SPI Silver Membrane filters which could be of additional value if you are contemplating the use of the silver membrane filters for your work.

Although the SPI Silver Membrane filters are used in a large number and variety of applications, their unique chemical and thermal stability is especially valuable for those applications involving aggressive fluids and/or high temperatures. They are ideal collection media for analysis of crystalline silica by x-ray diffraction and for analysis or organic materials by other instrumental techniques, such as the analysis of polyaromatic hydrocarbons (PAH). These are all in addition to the very popular and common application in the scanning electron microscope (SEM) laboratory since with a conductive substrate, one normally has a greatly reduced need to apply a conductive metal coating, something that can end up covering up important structure that other wise would be resolved.

The silver membrane filters are also used for high temperature filtration, sterilization, removal of microbial and particulate contaminants from fluids, under pressure, and in caustic liquids and gases. (Note: Silver membranes are not resistant to nitric and sulfuric acids or cyanide solutions). The unique combination of physical properties and retention and flow rates for the SPI Silver Membrane filters have led to an enormous number of different and diverse applications.

Life Science Researchers . . .

will find SPI Silver Membranes particularly useful for specimen preparation. Besides reducing the need to metallize specimens, they provide:

Highly conductive surface for mounting, for SEM, including biological specimens, especially when being collected from suspension (e.g. individual cells or small groups of cells, small particles, etc.).
Rigid support for direct SEM or LM viewing of specimens
Critical point drying substrate (behaves like a polymer membrane filter) of collected particular samples for later viewing, on the filter, by SEM (or LM).
Conductive surface often times leads to reduction or elimination of need for conductive metal for SEM observation, an advantage of particular importance to the life sciences researcher.
Excellent heat transfer surface for dimensional preservation of specimens during freeze-drying.
Bacteriostatic properties

Determining Free Silica: An Application Following NIOSH Methods

Air-jet milled quartz (SiO₂) used here to simulate quartz in respirable industrial dusts, illustrates the utility of SPI Silver Membranes for this analysis. The SPI Supplies brand of silver membrane filters meet the requirements of NIOSH procedures for the measurement of free silica.

SEM images show silver filter surfaces without and with particulate SiO₂. Corresponding x-ray diffraction patterns identify components before/after dusting with SiO₂.

Low x-ray background is evident and diffraction lines for Ag do not interfere with measurements of quartz line as do other substrates. * Bumstead, H. E. 1973 "Determination of Alpha-Quartz in the Respirable Portion of Airborne Particulates by X-Ray Diffraction". Amer. Ind. Hyg. Assoc. J. 34, 150-58.

* NIOSH Manual of Analytical Methods 1977. Method No.: P&CAM 259. Appendix 1, Vol. 1.
Supt. of Documents, U.S. Government Printing Office.
Washington, D.C. 20402 GPO #017-003-00267-3.

Other Research Applications:

Filtration of alcoholic beverages
High temperature processing of viscous materials
Performing mild chemical digestion directly at filter surface
High temperature stack sampling
High temperature sterilization procedure
Filtration involving organic solvents

Holding the membrane filters:
All membrane filters, offered by SPI Supplies, irrespective of their construction, must be used in conjunction with a specially made membrane filter holder.

Still need some additional technical information about the SPI Silver Membrane filters? It is all here!

Membrane Diameter 13 mm

Packages of 25
Pore size Diameter µm	SPI #	Each	In Stock
0.2	01170-CF	$ 133.81	Yes
0.45	01171-CF	133.81	Yes
0.8	01172-CF	133.81	Yes
1.2	01173-CF	133.81	Yes
3.0	01174-CF	133.81	Yes
5.0	01175-CF	133.81	Yes

Packages of 100
Pore size Diameter µm	SPI #	Each	In Stock
0.2	01170-MB	$ 535.24	No
0.45	01171-MB	535.24	No
0.8	01172-MB	535.24	No
1.2	01173-MB	535.24	No
3.0	01174-MB	535.24	No
5.0	01175-MB	535.24	No

Membrane Diameter 25 mm
Packages of 50
Pore size Diameter µm	SPI #	Each	In Stock
0.2	01180-FA	$ 313.12	No
0.45	01181-FA	313.12	Yes
0.8	01182-FA	313.12	Yes
1.2	01183-FA	313.12	Yes
3.0	01184-FA	313.12	Yes
5.0	01185-FA	313.12	Yes

Membrane Diameter 37 mm
Packages of 25
Pore size Diameter µm	SPI #	Each	In Stock
0.2	01160-CF	$ 278.85	Yes
0.45	01161-CF	278.85	Yes
0.8	01162-CF	278.85	Yes
1.2	01163-CF	278.85	Yes
3.0	01164-CF	278.85	Yes
5.0	01165-CF	278.85	Yes

Membrane Diameter 47 mm
Packages of 25
Pore size Diameter µm	SPI #	Each	In Stock
0.2	01190-CF	$ 395.83	Yes
0.45	01191-CF	403.51	No
0.8	01192-CF	395.83	Yes
1.2	01193-CF	403.51	Yes
3.0	01194-CF	395.83	Yes
5.0	01195-CF	395.83	No

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