Polycarbonate membrane filters are available with a black surface for staining applications.
Epifluorescent microscopy allows the direct observation and total enumeration of viable and nonviable organisms in less than 30 minutes as compared to traditional culturing methods that may require incubation times of up to 72 hours. Traditional culturing methods also underestimate the total number of micro-organisms in a sample due to the selective nature of the media employed, lack of detection of nonviable micro-organisms, and failure to count micro-organisms that are present as aggregates or associated with particles. The need to count the total population of micro-organisms may be important since the presence of large numbers in some samples may be significant, regardless of viability.
The epifluorescence microscopy technique has been used for the assay of micro-organisms in potable water, ultrapure water,food and dairy products, wines and beverages, parenterals, hydrocarbons and for general microbiological laboratory, medical, and research applications.
The basic procedure is simple and reproducible; a known quantity of liquid is filtered through a black polycarbonate membrane. The micro-organisms are stained on the surface of the filter with one or more dyes, and the fluorescing micro-organisms are observed using an epifluorescent microscope.
Black polycarbonate membrane filters are ideally suited for use in epifluorescent microscopy because:
- The micro-organisms are retained in one plane on the surface of the membrane filter
- The surface of the membrane filter is flat and smooth, assuring that no micro- organisms will be captured within the filter structure as with ordinary tortuous pore filters
- Polycarbonate membrane filters do not stain, and they exhibit extremely low nonspecific absorption
- Polycarbonate membrane filters are treated for essentially zero autofluorescence, each lot being tested. This assures high visibility against a nondistracting background
- Water Testing
- pH Range: 4-8
Standard polycarbonate membrane filters are treated by a proprietary irgalan black process to render them dark grey. This essentially eliminates the natural auto fluorescence of the membrane. Except for a reduction of normal transparency, the membranes have the same characteristics as standard polycarbonate membrane filters.
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