August 28, 2019

Testing THC Edibles: The Importance of Stability Testing in the Cannabis Field

Recently, the legalization of cannabis-infused edibles has been passed by several states in the U.S. Later this year, cannabis-infused edibles will be for sale in Canada, though Quebec has announced it will ban most edibles. This may be news to some as the legalization and sale of cannabis leaves and extracts are handled differently than that of a formulated edible. Whether for recreational or medicinal-use edibles impose new kinds of problems as the processed consumables possess different bioavailability and uptake routes in the body, leading to longer onset times and overdose potential when compared to standard inhalation methods. Label claims need to be met and verified in terms of potency testing and overall safety to the consuming public. Up to this point, testing has not generally been universally regulated due to the absence of a universal governing body to implement standards of what needs to be tested and what levels of accuracy are valid, leading to a wide range of quality within products. Many say that global legalization will actually allow for the expanded research of these drugs and their safety to the public, something that has obviously been difficult to do.

This will beg the question: “What needs to be tested for and what are the acceptable levels of and accuracy thresholds of testing?”

Merely testing the THC (tetrahydrocannabinol)amount of a beverage will not likely do justice. Edibles that contain THC are likely to get pharmaceutical treatment as their consumption, unlike CBD (cannabidiol), causes psychoactive effects and mood alteration. Proper dosing of the THC in a product is also important. Novice users are likely to be much more sensitive than seasoned individuals. One can imagine that if a 10 mg recommended dose of THC for a novice user is misrepresented by a few milligrams then the dosage will be well above the recommended amount.

The testing of THC edibles, such as beverages, will also result in additional complications compared to alcoholic beverages. The most popular mood-altering, regulated substance, ethyl alcohol is water-soluble and exists in a homogenous state throughout products such as beer, wine, and liquor. Conversely, THC is an oil and is incompatible with water. Enter the important role of the formulation chemist, responsible for properly suspending and dispersing this oil into an aqueous medium. Such emulsions can be quite stable for long periods of time as is the case with viscous cosmetic body creams or they can be relatively unstable as is the case with many vinaigrette-type salad dressings. More unstable emulsions carry a high risk of oil contents breaking out of the formulated matrix and creaming to the top of the product. And as opposed to safe olive oil, if an emulsion containing THC were to break and form a THC slick on the top of the beverage, in addition to simply tasting bad, the entire dose of psychoactive material can also be ingested within the first sip and potentially cause negative, possibly harmful effects for the consumers.

Testing for this type of stability does not fall in line with typical methods of THC testing that revolve around the content percentage of THC, THC/CBD ratios, phenotyping, or the presence of other toxic chemicals such as pesticides. Testing for emulsion stability is typically done with visual observation (simply waiting for the emulsion break to be visible and measuring the volume of each phase). However, some emulsions can be stable for months, if not years, and waiting for an emulsion to start showing signs of such would require a time period that can slow down the formulation and production process.

How then can this testing be done in a short period of time and with quantitative, accurate results?

At Formulaction, we have been working for over 25 years on a light scattering technology that can monitor emulsion stability and detect the smallest change well before anything can be observed by the naked eye. Based on the Static Multiple Light Scattering (SMLS), the Turbiscan device detects particle migration and size data to provide detailed comparisons of the creaming, clarification, sedimentation, and flocculation kinetics. Easy and rapid analysis of the THC creaming rate in an emulsion can be extrapolated into shelf life or can simply be used as a pass/fail test. Not only does this present itself as a solution to shelf life and potency testing but will also allow the formulating chemist to quickly and rapidly optimize the formulations.

This method has already been tested by Tarukino, LLC in Seattle, Washington. Since it is known that HPLC testing of materials can change from lab to lab even for the same samples it was determined that utilizing the Turbiscan for long-term potency testing would be a good fit. Sampling with the Turbiscan is simple and requires only placing the material inside of a 30 mL vial and sealing the cap. The same vial of an unaltered sample can sit upright for the entire duration of the test without the need for probing or stressing the sample in any way throughout the process. As the creaming of the sample is seen, the absolute volume fraction of oil can be calculated over time. Given the particle size (measured independently throughout the study) and the refractive index of the sample, the volume fraction can be calculated.

Users of the Turbiscan at Tarukino (Seattle, WA) see the creaming of a THC-infused emulsion over a 200-day period change no more than an absolute 1.75% change in the sample. With this critical information, they can be confident that their material can sit on a shelf for over 200 days without the need to worry about the quality of the product. Most importantly, the potency during this time will not be impacted in a significant manner and can likely be rendered homogeneous with simple redispersion (i.e. shaking).

Proper testing and validation of cannabis-infused products will likely require multiple methods in order to generate clean, viable, and stable products. While some testing methods may not be considered mandatory a collection of methods will result in consistently high-quality products that will ultimately help a brand develop and stand out from others in this competitive marketplace.




1)     “Tasty THC: Promises and Challenges of Cannabis Edibles”. Daniel G. Barrus, Kristen L. Capogrossi, Sheryl C. Cates, Camille K. Gourdet, Nicholas C. Peiper, Scott P. Novak, Timothy W. Lefever, Jenny L. Wiley. Methods Rep RTI Press. Author manuscript; available in PMC 2017 Jan 24. Published in final edited form as Methods Rep RTI Press. 2016 Nov; 2016: 10.3768/rtipress.2016.op.0035.1611.

2)     “The Cannabinoid Content of Legal Cannabis in Washington State Varies Systematically Across Testing Facilities and Popular Consumer Products”. Nick Jikomes & Michael Zoorob. Scientific Reports, volume 8, Article number: 4519 (2018)

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