FAQ Friday – Cannabis Production & Testing Edition

Posted on October 27, 2021

Why might you see the variability in the reported potency values in a single cannabis product? Why do some labs require higher sample volumes than others?

What happens behind closed laboratory doors shouldn’t be a secret! In this FAQ Friday series, we answer some of the most-asked questions when it comes to cannabis testing. Understanding the bigger picture can help you tailor a more efficient testing program, and think critically about the data you receive.

Why do labs ask for a higher sample volume than the minimum volume required for testing?

We ask for a higher sample volume not so we can store it for later, but in case we need to re-run a test. Our scientists are dedicated to giving you the most accurate results, which sometimes means re-runs or re-extracts are necessary. We also use an additional sample for quality control purposes, as required by some methods. The minimum sample volume can also vary between laboratories due to differences in the methods and validation processes followed by each lab.

Check out the handy sampling guide here, to see what sample volumes we require for testing. If you would like to discuss the possibility of submitting smaller volumes, you can reach out to one of our scientists and we would be happy to work collaboratively with you to find a testing solution that meets your needs.

Why do I see variability in my potency results?

Variability in potency results can be caused by a number of different factors, mainly relating to sampling, storage time and temperature, sample prep, and instrument uncertainty. Some products, such as oils and concentrates have inherently high cannabinoid potency. The acceptable range of variability due to measurement uncertainty is ±15% for potency which, for high potency values, can lead to a significant range of acceptable results. CARO monitors instrument performance and reports quality controls to our clients. While we do not have any involvement in setting the standards of required specifications for cannabis potency, CARO participates in proficiency testing programs in an effort to increase accuracy and precision, as well as following all guidance issued by Health Canada. 

Should I test my edibles for microbiological parameters, if the flower used in making that product has already been tested?

 Even if your concentrate has been tested, it’s common practice to test the final product for micro as well. (You can find more information about that here) There can be instances, however, of microbe contamination between the time after the bud is tested and the time that it is processed to make an edible product. CARO recommends additionally testing the final edible product to ensure you are releasing a product that is not only delicious but also safe for consumers.

How do you set your TATs, and why are they sometimes longer than the testing time?

A sample’s journey through the laboratory is much more than just testing! Turnaround Times (TATs) are established by the lab based on the sample hold time, login time, total extraction time (which can include incubation time and sample preparation time), data processing time, data/QC review time, and overall report assessment prior to release. To provide the most economical testing solutions for our clients (ie. the best cost to TAT ratio), samples are processed in batches and are not necessarily started the moment they reach our doorstep.
If you need your results sooner than our standard TAT, CARO does have rush options available. These rush TATs often incur surcharges to allow for the rush requestors’ samples to “jump the queue,” and often resulting in much smaller batch runs. It is important to note that not all tests can be expedited – some tests have longer processing times that cannot be compromised.


TATs are exclusive of weekends and holidays. This is an important detail to consider when choosing your TAT. When your samples are logged in you will also be sent a login notice that summarizes your request and identifies the due date. (Click here to learn more) We encourage all our clients to inspect this login notice to ensure that the due date matches your expectations (nobody likes bad surprises!)


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