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We have included some reference materials for your use. Please click on the descriptions below to review the specific subject matter. If you have any questions, please contact us or use our Live Chat and we can answer all your questions. If there are other topics that we can help you with, please let us know.We’re always here to assist with all your industrial hygiene questions and needs!

Microbial Sampling Procedures

The Zefon Air-O-Cell™ is an impaction-based air sampler, used in microbial sampling procedures, designed to pull air across a tacky sampling medium, trapping any airborne particulates. It is designed for use in conjunction with a high-flow vacuum pump set to 15 Lpm (liters per minute).

Utilize Air-O-Cells™ in the microbial testing:

  1. Carefully remove the rectangular labels covering the rectangular inlet and the round outlet from the Air-O-Cell™ and set labels aside.
  2. Attach round Air-O-Cell™ outlet to Air-O-Cell™ adapter.
  3. Turn vacuum pump on.
  4. Allow pump to run for a length of time depending upon sampling environment. The pump will turn off automatically after it has run the sampling event.
  5. Replace rectangular labels over the inlet and outlet of the Air-O-Cell™ to prevent contamination.
ENVIRONMENT SAMPLING DURATION
Clean office; outdoors on dry day 10 minutes
Average room with minimal visible dirt 5 minutes
Visibly contaminated area, with mold or airborne dust; outdoors on wet day (not during precipitation) 2 minutes

 

NOTES on Air-O-Cell™ Sampling:

  • Handle Air-O-Cells™ with care. Rough treatment may result in breakage of the sampling medium inside them, preventing analysis.
  • If the environment you wish to sample is not similar to those in the table above, a sampling duration of 5 minutes is best to obtain an adequate sample while minimizing chances of overcrowding on the sample.
  • Sampling for less than 2 minutes or more than 10 minutes is not recommended as data can be inaccurate i.e., not enough mold spores to accurately determine contamination or too many to count.
  • The investigator should stand away from the Air-O-Cell™ while a sample is being collected to avoid false readings. The Air-O-Cell™ should be mounted on a tripod or something similar, and the sample should be collected at breathing height (around 4-5 feet) to provide an accurate representation of occupant exposures.

The Biostage-1 or Andersen N6 viable impaction sampler is designed to sample air for viable or living microbes only. Air is pulled by a vacuum pump through the inlet cone, and then through the diffuser plate to impact a 100-mm agar plate on the stage. This traps particulates in the agar to promote growth of viable organisms to detectable levels.

Utilize The Biostage-1 or Andersen N6 viable impaction sampler in the following manner:

  1. Attach tubing to the vacuum pump and then to brass barb on sampler.
  2. Turn on the vacuum pump and set the rotameter to 28 Lpm (reading the middle of the ball) using the knob at the top of the rotameter.
  3. Turn pump off.
  4. Carefully wipe all surfaces of the aluminum sampler, inside and out, with isopropyl alcohol.
  5. Remove agar plate from cooler and place on top of pegs on the bottom stage.
  6. Remove lid of agar plate and set lid aside, face down to minimize contamination.
  7. Reassemble sampler.
  8. Turn vacuum pump on.
  9. Check pump rotameter and readjust to 28 Lpm as necessary.
  10. Allow pump to run for a length of time depending upon sampling environment.
  11. Turn pump off.
  12. Remove agar plate from sampler.
  13. Replace lid of agar plate.
  14. Label with a unique identifier, such as location and date sample was taken.
  15. Tape lid to bottom to prevent contamination and place agar plate within a zipper-lock bag and then into the cooler.
MICROBIAL SAMPLING DURATION
Clean office; outdoors on dry day 10 minutes
Average room with minimal visible dirt 5 minutes
Visibly contaminated area, with mold or airborne dust; outdoors on wet day (not during precipitation) 2 minutes

 

NOTES on Biostage-1 Sampling:

  • Handle agar plates with care. Rough treatment may result in breakage of the dish, which can contaminate samples.
  • Agar plates should be stored in the cooler with the agar face down. Condensation can collect on the lid and drip back into the culture, favoring the growth of some organisms over others and perhaps causing spread of some molds or bacteria within the plate, giving an inaccurate colony count.
  • Always transport agar in a cooler with “blue ice” before and after sampling. Cold temperatures slow the growth of microorganisms, allowing for more reliable analysis. Wrap the blue ice container in bubble wrap, thick cloth, or several paper towels to prevent contact between it and the agar plates. Avoid using regular ice, which can freeze the agar. Freezing the sample can damage it, leading to inaccurate data.
  • When sending the viable air samples, for mold air testing, back to Galson Laboratories for analysis, always ship them for next-day delivery ( if shipped on Friday, for Saturday delivery). This is to ensure that the sample remains at a lower temperature to prevent microbial overgrowth until it arrives at the lab for incubation and analysis. If next day shipping is not possible, store the samples in a refrigerator< until they can be shipped. Re-freeze the “blue ice” before reuse.
  • If the environment you wish to sample is not similar to those in the table above, a sampling duration of 5 minutes is best to obtain an adequate sample while minimizing chances of overcrowding on the sample.
  • Sampling for less than 2 minutes or more than 10 minutes is not recommended data can be inaccurate: i.e., not enough mold spores to accurately determine contamination or too many to count.
  • The investigator should stand away from the Biostage-1 sampler while a sample is being collected to avoid false readings. The sampler should be mounted on a tripod or something similar, and the sample should be collected at breathing height (around 4 to 5 feet) to provide an accurate representation of occupant exposures.
  • If the investigator needs to obtain data for both thermophilic (potential human pathogens) and environmental organisms, at least two samples must be taken. A single agar plate can only be incubated at one temperature. If the temperature is lower than freezing during sampling, care must be taken to prevent freezing of the plate. Freezing the media can prevent trapping of viable organisms and can damage those already trapped. Spore concentrations in the air change rapidly and constantly. Viable fungi air samples that are to be used in conjunction with Air-O-Cell™ samples should be taken at the same time to provide more accurate results.

A transport swab is a cotton-tipped swab with a protective case and media to preserve the sample during shipment. The swabs can be used for mold screens and viable analysis.

Utilizing a Transport Swab in the Microbial Testing Procedure:

  1. Pull apart the plastic wrapping of the swab until it is halfway open.
  2. Grasp the swab by the plastic handle at the top and remove from wrapping. Do not touch the shaft
  3. Designate a location to be swabbed, taking care to note the size of the area.
  4. Swab the entire area in a zigzag pattern, rolling the swab over to ensure the entire swab is used.
  5. Remove the cap from the swab case and discard.
  6. Carefully insert the swab into the case, making sure to seat the cap firmly on the case, and that the swab end is touching the media-soaked sponge at the bottom.
  7. Label the sample with a unique identifier, such as the location the sample was taken and the date.
  8. Place in a cooler to prevent microbial proliferation of the sample.

NOTES for SWAB SAMPLING

  • Some investigators prefer to sample with a wet swab rather than a dry swab as noted above. The media-soaked sponge in the swab case can be used for wetting the swab, as the media is sterile. Tap water should not be used as a wetting agent because it may contain microorganisms that could interfere with analysis.
  • The size of the swabbed area should be noted on the chain of custody. If a viable analysis is requested, a measure of CFUs per square centimeter can be obtained from this information. The area should be no larger than 10 cm by 10 cm, or roughly 4” x 4”, as too large an area may provide inaccurate data. Because several analyses can be performed from a single swab, there is no need to take multiple samples from the same area.
  • Swabs should be shipped in a cooler to arrive at the laboratory within 72 hours of collection to maintain sample integrity.

Transparent adhesive tape can be used to obtain a useful look at surface contamination. Most any tape that is clear can be used. The analysis will provide a rough quantitation of the level of surface contamination.

Obtain a tape sample in the following manner:

  1. Obtain a 2” (5 cm) piece of tape, being careful not to touch the middle of the piece.
  2. Hold the tape at one end between the thumb and forefinger.
  3. Place tape against the surface to be sampled.
  4. Gently press down on the tape using the other hand.
  5. Slowly peel the tape off of the surface.
  6. Affix tape sample flat against the inside of a clean zipper-lock plastic bag.
  7. Seal the bag and label it with a unique identifier, such as the sampling location and the date.
  8. Alternatively, use Bio-Tape™ provided by Galson.

Notes for Tape Sampling:

  • The tape used must be transparent, as the sample will be analyzed by direct microscopy, and therefore must be able to transmit light. Do not use electrical tape or frosted (“Magic”) tape, as no analysis can be completed.
  • Avoid creasing or folding the tape. The tape should be as flat as possible at all times to ensure accurate analysis. Creases interfere with the ability to visualize the trapped spores on the tape.
  • Tape samples can be analyzed only by direct microscopy. No viable analysis can be completed on a tape sample.

Bulk samples are pieces of material that can be tested for mold or bacterial contamination. These samples can include pieces of drywall, carpet, or other items. Bulk samples can be used for both screen and viable analysis.

To collect a bulk sample:

  1. While wearing gloves, obtain material and place in a zipper lock plastic bag.
  2. Label the bag with a unique identifier, such as the location the sample was obtained and the date.
  3. Place bag in a cooler to prevent overgrowth of microbes on the sample, which can corrupt results.

Notes for Bulk Sampling:

  • Samples should be no longer than 10 cm (about 4”) in any dimension. This reduces shipping costs and keeps analytical data more accurate.
  • Large samples, especially those with large areas that are free of visible mold, will dilute the sample and give deceptively low numbers.
  • Certain materials such as ceramics and metals, with hard, sealed surfaces, cannot support the growth of mold, and therefore do not generally make useful bulk samples.
  • The best bulk samples are commonly porous and/or organic in nature, such as wood or drywall.

Bulks should be shipped in a cooler to arrive at the laboratory within 72 hours of collection to maintain sample integrity.

Sampling Condensate/Standing Water

To sample condensate or standing water:

  1. Wear sterile plastic gloves.
  2. Remove sample vial from plastic bag.
  3. Remove cap from vial.
  4. Dip sample vial into condensate. Fill vial with approximately 2 milliliters of condensate.
  5. Replace lid on vial and seal tightly.
  6. Label the sample with a unique identifier, such as the location the sample was taken and the date.
  7. Read and record on the chain of custody the volume of water collected in the vial.

Notes for Water Sampling

  • Water samples should not be collected from public (city/county) water systems. These samples cannot be analyzed for microbes of any kind at Galson Laboratories.
  • Sampled water used in industrial processes should not contain toxic chemical compounds such as VOCs or heavy metals. Call Galson Laboratories at 888- 577-5227 for guidance.
  • Because several analyses can be performed from a single sample, there is no need to take multiple samples from the same source. When sending samples back to Galson Laboratories for analysis, always ship them for next-day delivery (if shipped on Friday, for Saturday delivery). Ship in a cooler to prevent microbial proliferation within the vial.

For questions on microbial testing procedures in mold air testing, amongst others, or to order sampling tubes, please contact client services at 888-432-5227.

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