How to read a COA
Compliance May 19
By Chad Frey 0 Comments

With almost anything we buy, there are certain parameters in place to ensure product safety and quality. Cannabis offerings are unique because people who use them cannot assume they are safe. The good news is that consumers can find high-quality cannabis products if they do their research. This is why we’re going to explain the importance of requesting and reviewing a Certificate of Analysis (COA), which should be available for any cannabis product that you use.

Determining the ideal cannabis product can be tricky, which is exactly why a Certificate of Analysis is so important. A Certificate of Analysis (COA) is a document provided by a third-party lab that analyzes some of the various compounds found in your cannabis. This can include outlining a strain’s cannabinoid (CBD, THC, CBG, etc.) and terpene (limonene, caryophyllene, etc.) profile as well as testing for other crucial factors like pesticide residues or heavy metals. You can also find other information in a COA such as manufacturer information, testing method used, and batch data.

Where to find a COA

All flowerz™ products have printed QR codes on the product’s outer packaging, which can be scanned to view the full COA report. Other companies publish COAs online in the product description portion of their website. If the COA is not transparent from one of these sources, consumers should consider contacting the company to request a COA before purchasing the product.


The ultimate function of a COA is to ensure a product’s content matches what was advertised, particularly with regard to potency and safety. As such the first element to consider when reading a COA is who the test was conducted by. This information can be found at the top of the first page.

You should always check to ensure the company that performed the test is not the original manufacturer as this is the best way to ensure independence and impartiality.

What to look for first

The first piece of information you’ll want to look at is the Report Date to be sure that the results are recent and relevant. Then you’ll want to confirm that the name of the third-party laboratory is listed prominently so that you can verify the lab’s existence and credentials (ISO 17025, DEA certified, etc.). Then you’ll want to look for the name of the product’s brand and cross-reference it with the brand listed on the product packaging.

The names should match unless the company contracted another manufacturer to make the product. If that’s the case, you may need to dig a little deeper to confirm that the COA is directly connected to the product in question. Finally, you’ll want to check that the batch number and description in the COA match what you see on the item you’re purchasing.

Understanding potency

You can determine potency by evaluating the concentrations of each cannabinoid present in the sample.

Most COAs will list cannabinoids in a column on the far left. This column may be labeled, “ID,” “Analyte,” or even just the name of the cannabinoids themselves. Both major cannabinoids (THC or CBD), as well as “minor” cannabinoids like THCA, are reflected here.

To the right of this column, you’ll find potency results.

Potency is determined by measuring the concentration of cannabinoids present in terms of total percentage by weight (mass). This can also be expressed as cannabinoid concentration in milligrams (mg) and may be featured in a column titled “Conc” (short for concentration).

One quick note on how THC and CBD levels are reported. Most labs don’t heat cannabis samples before testing them, so the THCA has not yet been converted into THC, a process called decarboxylation. Usually, labs will only predict the THC levels that will be in the final product should it be decarboxylated completely. For example, in the examples below, the lab has multiplied the THCA levels by a conversion factor to account for the decarboxylation process, predicting what the THC levels will likely be even though the majority of it is still THCA.


You may also spot a few specialized terms in a COA. These include:


Short for “below level of quantification,” this term is used to denote concentrations so small they do not meet the qualifying threshold for cannabinoid content.


Short for “limit of quantification,” this is the smallest concentration that can be accurately quantified.


“Limit of detection,” or LOD, is the smallest amount of cannabinoid(s) that can be detected by the instrument.

Loss on drying

Many COAs also provide information on the water content of a strain. This can be expressed as “moisture method,” “moisture content” or “loss on drying.” Loss on drying tests for the percentage of water content in the final product.

Contaminant Analysis Terminology

This analysis tests for the presence of any possible contaminants. A few common ones to look out for include:

Microbial contaminants

Generally bacteria, mold, or even yeast. Predetermined contaminant limits are established for each, i.e. “(Limit: <500,000 CFU/g)”. Most test results simply list “pass,” “fail,” or “absent” as results.


Aflatoxins are a type of mycotoxin produced by certain types of molds or fungi. Aflatoxins are very dangerous and may be potent carcinogens, which is why you definitely want to ensure your cannabis has no aflatoxins in it.

Testing for aflatoxins is mandatory in Canada under the Cannabis Act. In the United States, testing for Aflatoxins is contingent on the state you live in — some require testing while others do not.

Heavy Metals

Many CoAs also test for the presence of heavy metals as cannabis can be a bioaccumulator. These can include mercury, arsenic, cadmium, and lead. Any amounts of heavy metals present will be listed here.


CoAs often test for a variety of pesticides or plant growth regulators (PGRs) commonly used on cannabis.

Residual solvent screen

You may also encounter the term “residual solvent screen” on some CoAs. This term tests for the presence of any solvent leftover from the extraction process. Common solvents include butane, ethanol or hexane. This is relevant for extracts, including oils and vapes, but not dry flower.

What to look for in a contaminant analysis

Limits for each type of contaminant are established. For instance under “heavy metals” some CoAs will list heavy metal limits as 1.5 ppm (parts per million). Some analyses may list limits as PPB (parts per billion). A corresponding section will list pass/fail results.

You should always ensure that your cannabis has passed all of the tests for contaminants (“pass”). You’ll also ideally want samples that list “ND” (none detected) under heavy metals. Three classes are used to denote the level of danger associated with each solvent.

You can learn more about what to look for in solvents here.

Microbial levels are a little more tricky. Some countries, like Canada, require licensed producers to establish safe microbial limits. In the United States, microbial limits are up to the states themselves, if they set any. You can find more information about microbial levels in the US via this guide produced by the Cannabis Safety Institute.


When cannabis companies engage in third-party testing they’re showing that they value quality and customer safety above all else. Moreover, their willingness to publish the COA along with the product shows they are open and honest. During this time of great regulatory uncertainty, customers deserve nothing less than total transparency.

How to read a COA
How to read a COA

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