Laboratory Certificates of Analysis Demystified

Much of what occurs behind closed doors in an analytical laboratory might be rather daunting to clients of the lab. Discussions of error, significant figures, robustness, method optimization and validation, proper use of appropriate PPE (personal protective equipment), training records, reagent storage, limits of quantitation, and linearity, to highlight an ultra-limited few, are likely not the critical minutiae clients, such as cannabis farms or product manufacturers are combing through. The client sends the samples, and waits for the results.

Those results come in the form of Certificates of Analysis (CoA). While the individual templates used may vary by laboratory, several states (e.g. Washington, California) have regulated requirements in place for what each document must, at a minimum, contain. In Washington, for example, a CoA should include the following elements:

  • A title
  • Contact information for the lab and the client receiving the report
  • A unique identifier, such as the sample number
  • The identification of the methods used (liquid or gas chromatography, for example)
  • A description of the sample being analyzed (e.g. flower, concentrate, topical)
  • The date the sample was received
  • The test results (obviously)
  • The names, job titles, and signatures of the people authorizing the release of the data to the client
  • Whether or not the analyses are not covered under the lab’s certification
  • Documentation that the results reported fall within the range of the analytical method used
  • Documentation that any qualitative results, below the limit of quantification, but above the limit of detection, are reported as “trace” or an equivalent descriptor.

Now that you have some indication of what should be on a CoA, let’s take a deeper dive into a real one. ACS Testing Laboratories, in Florida, provided the following example:

As can be seen, the report has a title, and clearly displays the logo and relevant contact information for the lab. There is also a field for customer information. There is a detailed box that collects other pertinent details, such as the date that this extract sample was collected, and when the report was generated. It includes identifying features, such as the internal lab order number, and even provides the specific methodology used for evaluating the sample (“SOP-3”). The lab has included relevant sample weights and the density used in calculating weight percentages for some of the specific analytes described below.

This particular laboratory has chosen to provide potency information using both a concentration in milligrams per milliliter (weight per volume) and as a weight percent (weight by weight), which is the customary number listed on product labels. They’ve also provided their limit of quantitation (LOQ), which is simply the lowest concentration of an analyte that the lab can accurately measure, as determined from the validation of the method.

Moving down the report, next up is pesticides, and the lab has provided qualitative (“passed”) and quantitative information (the actual numbers). This is the same nomenclature used for heavy metals and mycotoxins, although you’ll notice that the units have changed, and heavy metals are reported as parts per billion (ppb), while mycotoxins are reported in micrograms per kilogram (µg/kg). This particular report showcases a sample that is contaminant-free.

Up next is the terpene/terpenoid content. This particular sample contained myrcene, limonene, and α-pinene, reported in milligrams per gram and as a weight percent. Lastly, the same was found to be free of microbiological organisms like yeast, mold, coliform, and Enterobacteriaceae, the latter of which includes E. coli and Salmonella.

You’ll also notice along the right side of the report that the lab has provided the type of instrumentation used for measuring each analyte. As mentioned above, this can be required by the state, but the inclusion of this information may also be important should a laboratory choose to send the same sample to multiple labs, since, should the labs use different instrumental methods, the concomitant numbers output by the methods would be expected to also differ.

The laboratory director has clearly signed off on the report, which provides accountability and traceability, and also highlights that the report has been checked over by multiple people prior to its submission to the client. And perhaps, most importantly, the lab has defined what various terms used within the report correspond to, and has demonstrated the calculations used in converting THCA and THC, and CBDA and CBD, to total THC and total CBD. This calculation is necessary, since there is a loss of mass through the decarboxylation of acidic cannabinoids (e.g THCA, CBDA) to their neutral (i.e. THC, CBD) counterparts. The 0.877 factor comes from the differences in molecular weights of the acidic and neutral molecules. For example, the molecular weight of THC is 314.45 grams per mole. A mole is a unit of measurement that corresponds to 6.022 x 1023 molecules. Given the cumbersome nature of that latter value, the shortened “mole” is used, much like a dozen corresponds to twelve things. The molecular weight of THCA is 358.478 grams per mole, and the ratio of THC over THCA leads to the 0.877 value. Another way to view this is that there is a 12.3% mass loss from the removal of the carboxyl group on the cannabinoid acids.

This report hits all of the relevant information in an easy to understand fashion. If the report you receive from your laboratory does not, ask them for clarification. Ultimately, if you don’t understand what your lab is telling you, the onus is on both the lab and you to rectify any confusion such that you can utilize the data that you’ve paid the lab to measure. Any laboratory worth sending your money to will take the time to help you understand what your data means.

Image Credit: Cosmos Magazine

About the author

Jason S. Lupoi, Ph.D.

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