How Fats May Interfere with Potency Testing in Cannabis-Infused Chocolate

For consumers, it seems like an easy question to answer: How much tetrahydrocannabinol (THC) is in that cannabis-infused chocolate bar? For analytical testers, however, the answers are anything but simple.

According to research published last year by David Dawson, PhD, a researcher with Vertosa, a cannabis technology company based in Oakland, Calif., chocolate contains compounds that interfere with labs’ abilities to determine the dose of cannabinoids infused into the product. Dr. Dawson and his team developed precise solutions of cannabinoids—the active ingredients in cannabis—added these to chocolate, and then attempted testing to prove the chocolate contained the exact volume of cannabinoids they had added. Over and over, they were only able to prove that some of the cannabinoids were present, but not all of them.

“Any time we get less [cannabinoids] than we expected, that’s a sign they’re having interactions with the chocolate,” Dr. Dawson says. “The only thing we changed was the identity of the chocolate, and the quantity.” He and his team found a straightforward trend that correlated with a few factors, one of which was that the more chocolate product in the vial, the lower the recovery of cannabinoids. “Chocolate was absorbing, interacting with, and trapping the cannabinoids, reducing the amount in the actual solution,” he adds.

In his research, Dr. Dawson looked at the four most commercially available cannabinoids: THC, known for the “high” associated with cannabis; cannabidiol (CBD), known for a variety of medical effects but also popularly embraced as a relaxation and wellness tool; and two lesser known cannabinoids, cannabinol (CBN) and cannabigerol (CBG), which have only started to appear in commercial cannabis products, in comparatively small doses. Dr. Dawson tested the four cannabinoids in three types of chocolate: dark, milk, and cocoa powder. Each interfered in some way with cannabinoid measurements.

Dr. Dawson is quick to stress that chocolate only poses a problem for analytical testers wishing to get an exact read on cannabinoid contents. “This doesn’t affect the product as it exists in real life,” he says. “The [same] amount of cannabinoids is there, regardless. It doesn’t affect how high you’ll get from eating the chocolate; it doesn’t affect the amount of cannabis in the chocolate. It’s just how we measure it that gets miscalibrated. This is an issue for analytical testing labs, not chocolate producers, and not consumers.”

That may be encouraging news for consumers and producers, but it does little to solve the mystery of how to accurately measure the dose of cannabinoids in infused chocolates.

Testing Specifics

Interestingly, Dr. Dawson notes that the four cannabinoids he tested behaved differently from each other: Roughly 10% of THC and CBN remained trapped in chocolate products, while CBD and CBG “had a slight downward trajectory, but recovery was fine by any analytical lab standard.”

He realized that THC and CBN molecules have a single phenolic hydroxyl (OH) group, while CBD and CBG have two. After synthesizing a cannabinoid with no OH groups, Dr. Dawson was able to prove that the more OH groups a product has, the more likely it is to create “signal suppression,” preventing analytical testers from getting a clear measurement. “If you have two OH groups, there’s basically no signal suppression; interaction with chocolate is minimal,” he says. “If you have one OH group, there’s a mild or moderate effect. If you have no OH group, there’s a strong effect.”

Amber Wise, PhD, scientific director for Seattle testing lab Medicine Creek Analytics, notes that the 10% difference Dr. Dawson and his team found is not uncommon. “To put analytical test results in this field into perspective, people need to be able to expect at least a 10% difference in the signal [indicating cannabinoids] between any two labs, or any two experiments in a given lab,” Dr. Wise says. “If the signal is 5, 10% of that is 0.5—it’s not the difference between 5% and 15%. This is not a place where we’re unable to test chocolate for cannabinoids or get the right answer. If you had a bad experience with an edible, it’s probably not because of this issue.”

Cannabinoid Solubility in Fats

Dr. Wise joins Dr. Dawson in lamenting how new the field of cannabis testing actually is, and how this isn’t just about chocolate, but about cannabinoids’ incredible solubility in fats, from which it is very difficult to get the dissolved molecules back out to measure their combined dose.