Trust the Facts, Not Gut Feelings: Lab Testing for Cannabinoid Levels
Growers often have a pretty good idea of the THC and CBD levels their plants will produce, but only a lab test can tell them the exact cannabinoid levels their cannabis contains.
I will begin with a confession: I am a lab geek. I love the lab and I enjoy solving mysteries that come from unexpected data. I really love knowing that, in my geeky way, I can help someone truly understand something they have a gut feeling about.
This is especially true with cannabis. (Another confession: I enjoy hearing about all the attention and care that goes into raising healthy and productive plants.) The growers I have met are extremely tuned in to their growing processes and thus have a good idea of what results they’ll get out of their plants.
They particularly have a good sense of what delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) levels they’ll see from a strain. Most often, their gut feeling is right; however, the only way they can know for sure is with a good lab test. Through this process, other lab geeks and I can let growers know exactly what their crop contains, including the levels of other medically important cannabinoids beyond THC and CBD.
If you want to know what medically relevant elements are in your product, get a cannabinoid potency and profile test. A good test will list the most commonly occurring cannabinoids—such as those listed in Table 1—and measure the concentration of each in your cannabis. Sometimes, this list will be separated into carboxylated compounds (that is, the acid forms; for example, tetrahydrocannabinolic acid, or THCA) and decarboxylated compounds (or, neutral forms; for example, THC).
Table 1: Medically Important Phytocannabinoids
|Decarboxylated||Cannabichromene (CBC)||Anti-inflammatory, antifungal, antibiotic, analgesic|
|Cannabidiol (CBD)||Anxiolytic, anti-inflammatory, antipsychotic, antispasmodic, analgesic|
|Cannabidivarin (CBDV)||Analgesic, mood disorder treatment, anti-inflammatory|
|Cannabigerol (CBG)||Antibiotic, anti-inflammatory, antifungal, analgesic|
|Cannabinol (CBN)||Sedative, anticonvulsant, antibiotic, anti-inflammatory|
|Delta-9-tetrahydrocannabinol (THC)||Euphoriant, anti-inflammatory, analgesic, antiemetic|
|Tetrahydrocannabivarin (THCV)||Appetite suppressant, analgesic, antiemetic, anti-inflammatory, euphoriant|
|Carboxylated||Cannabidiolic acid (CBDA)||Antiemetic, anti-inflammatory, antibacterial|
|Cannabigerolic acid (CBGA)||Analgesic, antibacterial, anti-inflammatory,|
|Tetrahydrocannabinol acid (THCA)||Antibacterial, antibiotic|
Indicators of Cannabis Product Age
Reliable product testing will also give an indication of how recently the cannabis was harvested. It does this by looking at the levels of carboxylated (acid form) cannabinoids and of a decarboxylated cannabinoid known as cannabinol (CBN).
High levels of CBN, which is formed from the breakdown of THC, indicate that a cannabis product has been sitting around for a long time. Same goes for low levels of acid-form cannabinoids. Carboxylation is the presence of a carboxylic acid molecule on a cannabinoid. Heat, light, or alkaline conditions can remove this molecule in a process called decarboxylation, which creates the active, neutral form of the cannabinoid. So, as plant material ages, its levels of acid-form cannabinoids begin to decrease.
- THCV: The Mysterious Cannabinoid
- Cannabinoid Biosynthesis: Growing Cannabinoids Without the Plant
- The Newest Cannabinoids: THCP and CBDP
Quantitation of Total Cannabinoids
A lab test can also report a total value of the cannabinoids. This is a calculation of what neutral forms of the cannabinoids would be present if there was a completely efficient decarboxylation process. A conversion factor is used to calculate this value.
For example, the levels of THC and THCA would be converted to a total measure of THC. If a sample had 10 per cent THCA, the total value of THC would be calculated to 8.77 per cent.
Available Testing Methods for Cannabis
There are a variety of rapid and highly sensitive methods for analyzing a product’s cannabinoid profile. Licensed Producers under Health Canada’s regulations must use a validated method that measures THC and CBD, but other growers have the option to choose a method that best suits them. The most common tests available are outlined in Table 2, which also looks at the benefits and drawbacks of each method.
Table 2: Comparison of Analytical Methods for Cannabinoid Potency
|Colorimetric||Inexpensive, rapid, can be done by a grower||Only able to show presence of THC or CBD over a threshold|
|Thin Layer Chromatography (TLC)||Inexpensive, rapid||Semi-quantitative method (the compound is present or absent over a certain concentration)|
|Enzyme-Linked Immunosorbent Assay (ELISA)||Simple, can be sensitive (able to correctly detect the presence of the compound of interest||Only able to detect THC and CBD, cross reactivity with other compounds known to occur.|
|Gas Chromatograph (GC)||Excellent for measuring small concentrations, sensitive, specific (able to differentiate between the compound of interest and compounds that may interfere with the test), accurate (measuring closely to the true value)||Unable to easily differentiate between carboxylated and decarboxylated compounds, measures total of each cannabinoid|
|High Performance Liquid Chromatography (HPLC)||Highly sensitive, very specific, accurate and precise (two or more measures agree), able to differentiate between carboxylated and decarboxylated compounds||Less efficient than GC, time-consuming|
As you may have guessed, thinking about the exciting and changing world of cannabis testing is my kind of fun. It can turn gut feelings into hard facts, making it an extremely useful tool for a grower. Cannabinoid testing can confirm what you know about your growing skills while showing you a world of other medically important cannabinoids that you have access to right in your own garden.
Written by Jodi McDonald
Jodi McDonald is the president and founder of Keystone Labs and is a medical microbiologist, inventor and super science-geek. She has 20 years’ experience in the quality control, regulatory, and quality assurance environment for the pharmaceutical industry. Jodi believes testing is essential for taking control of your personal health.