On the packaging for cannabis, you’ll see the levels of THC and CBD in the product. Many consumers choose their bud, edible, or extract based on the level of THC – some need a high amount to enjoy it, others need a low to moderate level. But have you ever wondered how these levels are determined?
Here’s how labs test cannabis for its THC level, and as such, can determine the product’s potency!
How Do Companies Determine THC Levels?
Cannabis potency measures the levels of delta-9-tetrahydrocannabinol (better known as THC) in weed. THC is the psychoactive ingredient in the cannabis plant; however, most THC in cannabis comes in the precursor molecular form tetrahydrocannabinolic acid, or THCA. THCA isn’t psychoactive, but when you heat the plant matter, the THCA loses the carboxylic acid group, producing the THC.
When measuring THC levels, many companies measure it as the concentration of both THCA and THC molecules. They do this by having labs perform tests on samples and detecting the levels of cannabinoid molecules using high-performance instrumentation.
There are many approaches in the cannabis industry to test the potency of weed, and the method is key to understanding the results. A method like high-performance liquid chromatography (HPLC) relies on passing the sample to a separation column using solvents (this separates the cannabinoids to allow measurement). It lets lab researchers preserve the THCA and quantify both it and the resulting THC for a more accurate potency measurement.
When using a method called gas chromatography, on the other hand, the lab heats a sample before introducing it to a separation column. The heat converts the THCA to THC. If you wish to capture the percentage of both THC and THCA to apply the potency calculation, gas chromatography is not the appropriate analytical method.
However the method, labs will arrive at the best approximation of the amount of THC (labelled as Total THC) using this equation:
% THC + (% THCA x 0.877)
This conversion factor takes into account the weight of CO2 lost through heating. They then report the number as a percentage by weight.
However, you may have noticed another number giving the THC level on some cannabis products. What’s the difference between the “Base” and “Total” THC numbers?
Base And “Total” Amounts: What’s The Difference?
Many products have two THC numbers, which can be confusing to casual users. Base THC – often labelled as “THC” – refers to how many active cannabinoids the product has when purchased. This is before the user heats the product through vaping, smoking or at-home extraction.
“Total THC” refers to the levels of active cannabinoids in a cannabis product after it has been prepared for consumption by heating. This cannabinoid content number is most helpful in predicting the potency so you can make the best choice.
Why Is Determining The Level Of THC Necessary?
Cannabis testing is the law because measuring the THC level is essential for many consumers. For one thing, weed is a lot stronger today: Health Canada reports that the potency of dried cannabis has increased from an average of 3% in the ’80s to roughly 15% today! If you were getting back into weed after decades of nonuse, the strain you choose would pack a surprising punch if you didn’t know what was in it.
Determining THC levels is also necessary for people using cannabis for therapeutic reasons. Patients who use medicinal weed must know how much is in it for specific effects. Recreational consumers have to know, too, because products can vary widely in their potency; this will influence the experience. If you’re someone who gets paranoid with high-THC strains, the percentage on the label can help you get a positive experience!