Many processes have been adopted for extraction and refinement of cannabis. Much like traditional botanical extractions, the aim of these techniques is to provide the desirable qualities of cannabis in a more readily usable form for the delivery method of choice. The wide range of options available has left processors questioning the best method for their extractions. A goal-oriented approach, focused on finding the best fit between process and physicochemical product attributes is critical. Pairing this goal-oriented process development with analytically guided optimization will allow for the development of an ideal process to deliver the best end product.
Post-extraction purification can range from simple filtration, often referred to as winterization, to more complex processes, such as distillation or preparative-scale chromatography. Again, the requirements of the end product should drive decisions here. Winterization leverages melting point differences between the various components in an extract to precipitate out unwanted waxes at a reduced temperature. It is then possible to filter away those waxes while retaining most of the other compounds in the extract. This means that while winterization can reduce the overall viscosity of the extract and increase the cannabinoid potency, it will have little effect on the overall color and clarity of the finished extract. If, for example, the end product can use oil of any color or clarity, but the formulation can’t handle some of the plant waxes that may have been coextracted by an ethanol solvent, then winterization may be a perfect choice.
Distillation can purify an extract by selective evaporation. By evaporating, condensing, and collecting the various fractions of an extract that evaporate at different temperatures, an operator can pull a highly pure cannabinoid fraction, often referred to as distillate. This distillate will be very high in cannabinoid potency, will be light in color, and will have high clarity, but it will not retain many of the other compounds from the raw material. In fact, because of the high temperatures required for the distillation of cannabinoids, many bioactives in the extract can be degraded in the process. Therefore, if a product demands a fuller spectrum of cannabis bioactives, distillation may not be the ideal technology, but if a high clarity, high cannabinoid potency extract is the goal, it may be a good choice.
Lastly, preparative-scale chromatography can purify the compounds in an extract based on their affinity to the stationary phase within a chromatography column. This process will provide the highest levels of purity for individual cannabinoids (upwards of 95% pure), but will separate out the vast majority of other compounds. This purification process produces an extract that allows a product developer to formulate with highly pure cannabinoids, but it will not deliver the complete efficacy of the raw material.
This small snapshot of the options available shows just how complex the task of process development can be in the cannabis industry. The keys to effective process development are having a complete understanding of the physicochemical attributes the end product demands, and relying on analysis to provide feedback when optimizing processes. By keeping these considerations in mind as guidelines, finding the answer to “what’s the best for my product?” can be a straightforward, though still laborious process.
Christian Sweeney is the Director of Science & Technology at Cannabistry Labs in Denver, Colorado. Direct correspondence to: [email protected]
- J.C. Raber et al., The Journal of Toxicological Sciences 40(6), 797-803 (2015), doi:10.2131/jts.40.797.
- Colorado Department of Revenue, Marijuana Enforcement Division, “Recently Adopted Retail Marijuana Permanent Rules - Effective January 1, 2018.” https://www.colorado.gov/pacific/enforcement/med-rules, p. 123.
- C. Sweeney, “Cannabis Extraction and Refinement in Colorado: A 5,280 Ft. View” presented at the Cannabis Science Conference, Portland, Oregon, 2017.
- M. Mukhopadhyay, Natural Extracts Using Supercritical Carbon Dioxide (CRC Press, Boca Raton, Florida, 2015).
How to Cite This Article
C. Sweeney, Cannabis Science and Technology 1(1), 54-57 (2018).