Cannabinoid profiling informs patients and consumers of the concentration of active cannabinoids present within a sample. Though some may refer to cannabinoid profiling as identifying a given “strain” of marijuana, this term is nebulous and dated.
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The term “strain” has no official ranking status in botany, and though it may be used to market and identify to the common consumer, researchers work under the model of percent Δ-9-tetrahydrocannabinol (Δ-9-THC), percent cannabidiol (CBD), etc. For this reason, the “Cannabinoid Profile” is a more precise metric of what the consumer is purchasing.
The importance and preliminaries of cannabis profiling
Two of the most important cannabinoids found in the marijuana plant are Δ-9-THC and CBD. While (Δ-9-THC) is the psychoactive ingredient, stimulating cannabinoid receptors to elicit euphoric sensations, CBD draws on other health benefits such as anxiety reduction and antitumor effects. These are closely monitored and looking at the general trends of potency within these cannabinoids, we see an increase in Δ-9-THC, and a subsequent lowering of CBD percentage from the years 1995 to the present.
From this data, our labs have been able to manipulate the psychoactive ingredients of this drug in accordance with consumer preference. We can obtain this information from the extensive cannabinoid profiling that has been done over the recent years, accompanying the accumulative popularity of this drug.
Though it is widely assumed that Δ-9-THC and CBD are the only cannabinoids routinely monitored in the laboratory under cannabinoid profiling, screening is also conducted for Δ-9-tetrahydrocannabinolic acid (Δ-9-THCA), cannabidiolic acid (CBDA), and cannabinol (CBN). In the world of large-scale cannabis production, manufactures must be made aware of the yields and potency of their marijuana products. To do this standard testing conditions are put in place for all to follow.
The minimum sample required for testing is dependent on the product itself. In addition, the number of tests performed should directly correlate with the total lot size. While plant material (the flower itself) is typically tested at 2 grams, marijuana concentrates are often tested at 1 gram, waters and drinks are tested at 60 mL, and 4 units of infused products are tested at a time.
Preparation methodologies of cannabis potency testing
When testing for the potency of cannabinoids, different pretreatments must be taken for different marijuana products. If one were to test the plant itself, the unrefined product would be ground in a fine powder, an appropriate solvent such as methanol would be added, the solution would be properly vortexed and centrifuged, and then fit to a high-performance liquid chromatography (HPLC) instrument for analyses.
Other products, such as edibles and other infused products require further sample preparation.
For these products, testing may mimic the “CEN Standard Method EN 15662”, and the “AOAC Method 2007.01”, traditional forms of assaying that originate from identifying pesticide residues in food and plant origins. This will incorporate the loose extraction salts and cleanup sorbents, in conjunction with centrifugation and purification.
A study undergone by K. Stenerson et al., 2018 shows how cannabinoid profiling can be performed on edibles and other infused products. The product in question, a brownie, and acetyl nitrile was introduced to a tube, which was shaken to form a homogenized mixture. Salts were then added followed by centrifugation, allowing for the co-extraction of fat and cannabinoids. The organic layer was then placed in a refrigerator for a predetermined period, and the extract was ultimately analyzed by HPLC.
In this test, it is apparent that the salts in question were used for extraction, phase separation, and buffering, while the sorbents cleanup, and remove unwanted interferences. This yielded an >80% recovery and a % RSD < 5.
Quantitative analysis through chromatographic means
If derivatization of cannabinoids within a sample is not feasible, which can often be the case when constructing a cannabinoid profile of varying assortments of marijuana products, one must choose the correct method of analysis. This will allow researchers to avoid compromising the veracity of said result.
Processing can jeopardize the cannabinoid content and consistency when constructing a cannabinoid profile. This is especially true for extracts, given that many times when extracts are made from concentrates, they undergo processes that can alter the acidic forms of the drug D9-THCA, into their neutral forms Δ-9-THC. This gives a false appearance of greater amounts of the psychotropic analyte within the medium.
This phenomenon is the reason why, if sample derivatization is non-viable, HPLC fitted with a diode array detector is often used. In gas chromatography-mass spectrometry (GC/MS), Δ-9-THCA is readily converted to Δ-9-THC by heating, through the process of decarboxylation. This occurs when injected into the GC because the injection port is heated to allow the phase change from liquid to gas, yielding an unfitting amount of the psychoactive analyte. If one were to look at the resulting chromatograph, the Δ-9-THCA and Δ-9-THC would elute as one peak.
For this reason, HPLC coupled with MS is used to distinguish between differing cannabinoids because no heat is involved. This will result in well-resolved peaks, making it much better for cannabinoid profiling.
- Melissa M. Lewis, Yi Yang, Ewa Wasilewski, Hance A. Clarke, and Lakshmi P. Kotra (2017). “Chemical Profiling of Medical Cannabis Extracts” ACS Omega 2 (9), 6091-6103
- Marianne Hädener, Michael Z. Kamrath, Wolfgang Weinmann, and Michael Groessl (2018). “High-Resolution Ion Mobility Spectrometry for Rapid Cannabis Potency Testing” Analytical Chemistry 90 (15), 8764-8768
- Michele Protti, Virginia Brighenti, Maria Rita Battaglia, Lisa Anceschi, Federica Pellati, and Laura Mercolini (2019). “Cannabinoids from Cannabis sativa L.: A New Tool Based on HPLC–DAD–MS/MS for a Rational Use in Medicinal Chemistry” ACS Medicinal Chemistry Letters 10 (4), 539-544
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