Operating Instructions

                                           863 Valley View Road, Eighty Four PA 15330 USA

                           Tel: 724-941-9701 Fax: 724-941-1369 e-mail: skctech@skcinc.com









                               Gelatin Filters

                    Cat. No. 225-9551 and 225-9552





SKC Gelatin Filters are designed for the detection and analysis of airborne

microbes. Gelatin filters not only retain bacteria and molds, but are also effective for

the collection of viruses. Used to quantitatively collect airborne microorganisms,

gelatin filters have an inherent high moisture content that helps to maintain

viability of stress-sensitive microorganisms during short sampling periods. The

gelatin material can be dissolved easily in a buffer or agar medium for easy

detection of bacteria and viruses.







Performance Profile:

Material: ...............Water-soluble gelatin

Pore size: ..............While having a nominal pore size of 3.0 µm, a higher capture

                          efficiency of sub-micron particles can be expected due to the

                          separations that occur on the surface and within the filter. It

                          is through inertial impaction and diffusional interception that

                          these filters can remove particles much smaller than 3.0 µm.

Diameter: .............25 mm or 37 mm

Thickness: ............250 µm

Max. temp: ...........60 C

Water content: .....80%

Limiting

conditions: ...........Room temperature max. 30 C, relative humidity 85%

Sterilization: ........Presterilized by gamma radiation.

Storage: ................Gelatin filters may be stored in low humidity, ambient

                          conditions, but refrigerated storage is recommended.

                          Caution: Do not freeze gelatin filters. Any condensation that

                          forms during thawing will dissolve filter. Avoid exposing

                          filters to moisture, chemical vapors, and extreme temperatures

Shelf-life: ..............3 years from date of manufacture

Analysis: ..............Direct method or indirect method (see pages 3 and 4).









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Operation

Filter Handling Guidelines

� Gelatin filters are brittle; handle filters carefully

� Do not touch filters with fingers or foreign objects

� Use forceps to handle filters.

� Do not grip filters too tightly with forceps; this will cause breakage.

� Avoid bending filters.

� Keep pocket on filter until ready to load into a cassette. See Loading a Gelatin

    Filter into a Cassette.





Loading a Gelatin Filter into a Cassette

Note: Load the filter only under sterile conditions. Follow Filter Handling Guidelines.



1.   Disassemble the cassette and carefully let the gelatin filter slide out of its

     pocket into the cassette.

2.   Use forceps to aid in positioning the filter.

3.   Reassemble the cassette.

4.   Use flexible tubing to connect the outlet of the cassette to the inlet of an

     air sample pump capable of the desired flow rate.

5.   Sample for the appropriate sampling period. Sampling periods should be

     brief to help reduce microorganism stress.





Handling and Shipping the Filter after Sampling

Determine the method of analysis to be used, direct or indirect, before preparing

the sample for shipment. There are two methods for shipment preparation.

Method 1 can be used for shipping to a laboratory at a different location.

Method 2 should only be used if there is an on-site laboratory that can perform

microbial analysis.



Method 1

Note: This method prepares the sample for the indirect analysis method.

1. Turn off the pump.

2. Disassemble the cassette and use forceps to gently remove the filter. Place it

    in 10 ml sterile water. (10 ml is recommended. Add more water, if needed.)

3. Once the filter dissolves, pour the solution in a water-tight container or tube.

4. Seal container and ship to a laboratory for analysis. See Analysis & Additional

    Application Notes.



Caution: Avoid extreme temperatures during storage and shipping.

Method 2

Note: Use this method only if there is an on-site laboratory. Determine the

appropriate agar before collecting the sample. These steps prepare the sample for the direct

analysis method.

1. Turn off the pump.

2. Open the cassette.

3. Place a prepared agar-filled petri dish base over the filter in the cassette until

     they are touching. The gelatin filter will adhere to the agar surface.

4. Carefully lift the agar plate base with the gelatin filter.

5. Immediately cover the petri dish base with its lid.

6. The gelatin filter will dissolve due to the moisture in the agar culture

     medium allowing the microbes to come into direct contact with the nutrient

     medium. The plates are incubated and the colonies counted. See Analysis &

     Additional Application Notes.





Analysis & Additional Application Notes

Direct Method

Note: This method is not recommended for virus aerosols.

1. After transferring the filter to the culture medium,

    incubate it in an incubator with the lid of the petri

                                                                      Direct Method

    dish facing up.

                                                                          Sample

Note: To prevent liquid from collecting on the agar surface,                  �

always use predried agar that is not freshly prepared.              Gelatin filter to agar

                                                                              �

2.   Choose the time, temperature, and type of culture            Dissolve gelatin on agar

     medium suitable for the target microbes. Follow                          �

                                                                         Incubate

     these guidelines:

                                                                              �

                                                                           Count

� Standard, Caso, or Plate Count Agar are suitable for

  determining colony count (total CFU count).

� Sabouraud, Malt Extract, or Wort Agar can be used

  for detecting yeasts and molds.

� Blood Agar is suitable for detecting pathogenic microbes causing hemolysis.



3.   Count the colonies that form.

Indirect Method

Dissolving Gelatin Filters after Sampling Airborne Microbes

This method is used to prevent osmotic shock to

the sampled organisms, to provide sub-samples for             Indirect Method

removal of inhibitors such as disinfectants, for dilution

                                                                   Sample

of the sample where high counts are expected, or to

                                                                      �

allow plating onto different nutrient media where

                                                          Dissolve gelatin in sterile

species identification is required.                                solution

                                                                                 �

1.   Dissolve the gelatin filter in sterile liquid warmed            Filter solution through

     to 35-40 C, such as physiological saline or 0.1%                    membrane filter

     peptone water.                                                              �

                                                                          Filter to agar

2.   Stir the solution using a sterile magnetic stirrer to

                                                                                 �

     accelerate filter dissolution.

                                                                             Incubate

3.   Process the solution according to Koch’s pour plate

                                                                                 �

     method or the membrane filtration technique.                              Count

4.   Incubate samples.

5.   Evaluate colonies that form.



Note: During the dissolving and stirring process (indirect method), the colony-forming

units are separated into individual microbes so you will obtain a higher CFU count than

with directly placing the exposed filter on a culture medium (direct method).





Calculation of Colony-forming Units per m3

To determine the quantity of colony-forming units per cubic meter of air (CFU/

m3), compare the number of colonies in relation to the volume of air originally

sampled.



Removing Disinfectants

Note: It is strongly recommended that you use the indirect method when analyzing

samples from an area sprayed with disinfectants, or where antibiotic airborne particles are

present. Using this method allows the removal of the disinfectants that inhibit the growth

of microbes on the culture medium. Follow this procedure:



1.   Dissolve the gelatin filter as instructed above.

2.   Before Step 3, filter the resulting liquid through a 0.45 µm pore size

     membrane filter.

3.   Add sterile water to rinse the filter.









Notice: This operating instruction may not address all safety concerns (if any) associated with

this product and its use. The user is responsible for determining and following the appropriate

safety and health practices and regulatory limitations (if any) before using the product. The

information contained in this document should not be construed as legal advice, opinion, or

as a final authority on legal or regulatory procedures.

                                                                      Form # 40060 Rev 0702