How to Collect Samples and Test for Mold or Bacteria

Start Testing for Mold by Collecting Tape Samples:

Laboratory results are as good as the sample. The sample type taken generally depends on the purpose of the investigation. The importance of accurate results cannot be overstated. Test results change people’s lives.

Tip. Collecting a good sample for lab testing. There’s not much point using a lab analysis report to guide your microbial remediation decisions or recommendations unless the sample collected for analysis was truly representative of the total building contamination. The aim should always be to collect the most representative sample possible. See our course How To Take Mold Samples.

In this first section, you will learn how to safely collect and send samples for mold testing services.

  • Cut 2-3 inches of clear scotch tape; avoid touching the sticky side by holding the piece of tape by the edges
  • Press the tape gently onto the surface you wish to test for mold growth
  • Peel the tape off surface holding the tape by the edges only
  • Apply sticky side of tape to the inside of the ziplock bag; do not fold the tape
  • Close bag and label the sample appropriately (put only one sample per bag)
  • Fill the chain of custody form and send it together with the samples to us.

How To Collect Bulk Samples for Mold Testing:

  • Wear suitable gloves
  • Cut a small piece (about 4 square inches) of the suspect material (e.g., carpet, drywall, wallpaper, wood); taking care not to disturb the mold
  • Place the sample inside a clean plastic bag (for example ziplock)
  • Close the bag and label the sample appropriately
  • Fill the chain of custody form and send it together with the samples to us.
Types of Samples

Types of Samples

How To Collect Swab Samples for Mold or Bacteria Testing:

Dry swabs are recommended for wet surfaces and wet swabs for dry surfaces.

  • Wear suitable gloves
  • Remove swab from tube (If using swabs with a wetting agent, drain most of it on the sides of the tube before sampling)
  • Swab the test surface by rolling the swab lightly back and forth. For quantification of the amount of mold or bacteria on the test surface, swab a known surface area (for example, 100 square centimeters)
  • After swabbing, insert the swab in the tube – Firmly close cap and label the sample appropriately
  • Fill the chain of custody form and send it together with the samples to us.

How To Collect Air Samples (Non-Culture) for Airborne Mold Testing:

Various sampling cassettes can be used. Use the manufacturer’s instructions. Also ensure the pump has been calibrated to the appropriate flow rate for the type of cassette to be used.

Note: replace stickers on Air Sampling Cassettes once sampling is completed to prevent contamination.

How To Collect Air Samples For Culture Analysis:

Settle Plate Samples

  • Select suitable agar media for sampling
  • Place the plates at table-top level and remove the lids
  • Leave the plates open for 0.5-4 hours
  • Cover the plates and secure the lids with clear tape
  • Label the plates with appropriate information
  • Place the samples in a cooler/box ensuring the samples are not in contact with ice packs (to avoid having the samples frozen)
  • Fill the chain of custody form and send it together with the samples to us for incubation and identification of the resulting mold or bacteria.

How To Collect Air Samples (culturable) for Mold or Bacteria Testing

Volumetric air samples for culture analyses are taken by impacting a known volume of air onto a suitable growth medium. Commonly used samples are Reuter Centrifugal Sampler (RCS) or the Anderson Single Stage Sampler. This process is particularly important if you request MBL’s bacteria testing service. Please refer to the manufacturer’s instructions on how to take samples using your sampler.

Key Points To Remember:

  • Use a permanent marker to label the samples
  • Complete a chain of custody form (sample submittal form) with the relevant information
  • For air samples, record the flow rate and sampling time or the total air volume collected on the form
  • Secure the samples and the chain of custody form in a shipping container
  • For samples that do not require culturing, refrigeration is usually not needed when submitting the samples to the laboratory for analysis
  • When collecting samples, write down and include with the sample(s) the following information, or download and fill out our Analysis Request Form:
    • Name
    • Company (if applicable)
    • Mailing Address
    • Telephone Number (voice) and fax number (if applicable)
    • Email address (if any)
    • Date sample taken
    • The type of analysis required (if not sure call the lab)
    • Turnaround time required for non-viable analysis: regular (1-3 days) or rush (24 hours

If you are within the GTA region, you can either deliver the samples to the laboratory by hand or send them by courier or post. Samples from anywhere else in Canada (outside the GTA) may be sent by courier or post.

Note: It is recommended that wet and/or culturable samples be sent to the laboratory on the same day if possible) or by overnight courier, and should be shipped under cool conditions (but not frozen).

When we test for moulds or bacteria, our turnaround time for all culture analyses is 10-14 days. Non-culture analyses takes 1-3 days for regular service and 24 hours for rush service.

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