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Dr. Ed Askew
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Distillation Of Your Cannabis Extract: Ignorance Is Not Bliss

By Dr. Edward F. Askew
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Dr. Ed Askew

In a previous article I discussed the elephant in the room for clients of laboratory services- the possibility of errors, inaccurate testing and dishonesty.

Now, I will explain how the current “smoke and mirrors” of distillation claims are impacting the cannabis industry in the recreational and medical areas. We have all heard the saying, “ignorance is bliss.” But, the ignorance of how distillation really works is creating misinformation and misleading consumers.

That is, just because a cannabis extract has been distilled, doesn’t mean it is safer.There have been reports of people claiming that “Distilled cannabis productsthat are Category 2 distillate are pesticide free and phosphate free, while Category 1 has pesticides and phosphates, but within acceptable limits”

The problem is that these claims of Category 1 and Category 2 cannot be proven just by saying they are distilled. Ignorance of the physical chemistry rules of distillation will lead to increased concentrations of pesticides and other organic contaminants in the supposedly purified cannabis distillate. That is, just because a cannabis extract has been distilled, doesn’t mean it is safer.

So, let’s look at a basic physical chemistry explanation of the cannabis distillation process.

  • First off, you must have an extract to distill. This extract is produced by butane, carbon dioxide or ethanol extraction of cannabis botanical raw material. This extract is a tarry or waxy solid. It contains cannabinoids, terpenes and other botanical chemicals. It will also contain pesticides, organic chemicals and inorganic chemicals present in the raw material. The extraction process will concentrate all of these chemical compounds in the final extract.
  • Now you are ready to distill the extract. The extract is transferred to the vacuum distillation vessel. Vacuum distillation is typically used so as to prevent the decomposition of the cannabinoid products by thermal reactions or oxidation. Under a vacuum, the cannabinoids turn into a vapor at a lower temperature and oxygen is limited.
  • Part of the vacuum distillation apparatus is the distillation column. The dimensions of this column (length and width) along with the packing or design (theoretical plates) will determine the efficiency of distillation separation of each chemical compound. What this means is that the more theoretical plates in a column, the purer the chemical compound in the distillate. (e.g. Vigreux column = 2-5 theoretical plates, Oldershaw column = 10-15 plates, Sieve plate column = any number you can pay for).
  • The temperature and vacuum controls must be adjustable and accurate for all parts of the distillation apparatus. Failure to control the temperature and vacuum on any part to the apparatus will lead to:
    • Thermal destruction of the distillate
    • Oxidation of the distillate
    • Impure distillate

Now, you can see that a proper distillation apparatus is not something you throw together from a high school chemistry lab. But just having the proper equipment will not produce a pure cannabis product. The physical chemistry that takes place in any distillation is the percentage a chemical compound that occurs in the vapor phase compared to the percentage in liquid phase.So, how can you produce a cannabis distillate that is clean and pure?

For example, let’s look at whiskey distillation. In a simple pot still, alcohol is distilled over with some water to produce a mixture that is 25%-30% ethanol. Transferring this distillate to an additional series of pot stills concentrates this alcohol solution to a higher concentration of 85%-90% ethanol. So, each pot still is like a single theoretical plate in a distillation column.

But, if there are any chemical compounds that are soluble in the vapor produced, they will also be carried over with the vapor during distillation. This means that pesticides or other contaminants that are present in the cannabis extract can be carried over during distillation!

So, how can you produce a cannabis distillate that is clean and pure?

  • Produce a cannabis extract that has lower concentrations of bad chemicals. Since a lot of the cannabis extracts available for distillation are coming from grey-black market cannabis, the chances of contamination are high. So, the first thing to do is to set up an extraction cleanup procedure.
    • An example of this is to wash the raw extract to remove inorganic phosphates. Then recrystallize the washed extract to remove some of the pesticides.
  • Make sure that the distillation apparatus is set up to have proper temperature and vacuum controls. This will limit production of cannabis decomposition products in the final distillate.
  • Make sure your distillation apparatus has more than enough theoretical plates. This will make sure that your cannabis distillate has the purity needed.
  • Finally, make sure that the staff that operates the cannabis distillation processes are well trained and have the experience and knowledge to understand their work.

Inexperienced or under-trained individuals will produce inferior and contaminated product. Additional information of extract cleanup and effective vacuum distillation can be obtained by contacting the author.

extractiongraphic

The Four Pillars of Cannabis Processing

By Christian Sweeney
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extractiongraphic

Cannabis extraction has been used as a broad term for what can best be described as cannabis processing. A well-thought-out cannabis process goes far beyond just extraction, largely overlapping with cultivation on the front-end and product development on the back-end1. With this in mind, four pillars emerge as crucial capabilities for developing a cannabis process: Cultivation, Extraction, Analytics and Biochemistry.

The purpose and value of each pillar on their own is clear, but it is only when combined that each pillar can be optimized to provide their full capacities in a well-designed process. As such, it is best to define the goals of each pillar alone, and then explain how they synergize with each other.

At the intersection of each pillar, specific technology platforms exist that can effectively drive an innovation and discovery cycle towards the development of ideal products.Cultivation is the foundation of any horticultural process, including cannabis production. Whether the goal be to convert pigments, flavors or bioactive compounds into a usable form, a natural process should only utilize what is provided by the raw material, in this case cannabis flower. That means cultivation offers a molecular feedstock for our process, and depending on our end goals there are many requirements we may consider. These requirements start as simply as mass yield. Various metrics that can be used here include mass yield per square foot or per light. Taken further, this yield may be expressed based not only on mass, but the cannabinoid content of the plants grown. This could give rise to a metric like CBD or THC yield per square foot and may be more representative of a successful grow. Furthermore, as scientists work to learn more about how individual cannabinoids and their combinations interact with the human body, cultivators will prioritize identifying cultivars that provide unique ratios of cannabinoids and other bioactive compounds consistently. Research into the synergistic effect of terpenes with cannabinoids suggests that terpene content should be another goal of cultivation2. Finally, and most importantly, it is crucial that cultivation provide clean and safe materials downstream. This means cannabis flower free of pesticides, microbial growth, heavy metals and other contaminants.

Extraction is best described as the conversion of target molecules in cannabis raw material to a usable form. Which molecules those are depends on the goals of your product. This ranges from an extract containing only a pure, isolated cannabinoid like CBD, to an extract containing more than 100 cannabinoids and terpenes in a predictable ratio. There are countless approaches to take in terms of equipment and process optimization in this space so it is paramount to identify which is the best fit for the end-product1. While each extraction process has unique pros and cons, the tunability of supercritical carbon dioxide provides a flexibility in extraction capabilities unlike any other method. This allows the operator to use a single extractor to create extracts that meet the needs of various product applications.

Analytics provide a feedback loop at every stage of cannabis production. Analytics may include gas chromatography methods for terpene content3 or liquid chromatography methods for cannabinoids 3, 4, 5. Analytical methods should be specific, precise and accurate. In an ideal world, they can identify the compounds and their concentrations in a cannabis product. Analytics are a pillar of their own due simply to the efforts required to ensure the quality and reliability of results provided as well as ongoing optimization of methods to provide more sensitive and useful results. That said, analytics are only truly harnessed when paired with the other three pillars.

extractiongraphic
Figure 1: When harnessed together the pillars of cannabis processing provide platforms of research and investigation that drive the development of world class products.

Biochemistry can be split into two primary focuses. Plant biochemistry focuses back towards cultivation and enables a cannabis scientist to understand the complicated pathways that give rise to unique ratios of bioactive molecules in the plant. Human biochemistry centers on how those bioactive molecules interact with the human endocannabinoid system, as well as how different routes of administration may affect the pharmacokinetic delivery of those active molecules.

Each of the pillars require technical expertise and resources to build, but once established they can be a source of constant innovation. Fig. 1 above shows how each of these pillars are connected. At the intersection of each pillar, specific technology platforms exist that can effectively drive an innovation and discovery cycle towards the development of ideal products.

For example, at the intersection of analytics and cultivation I can develop raw material specifications. This sorely needed quality measure could ensure consistencies in things like cannabinoid content and terpene profiles, more critically they can ensure that the raw material to be processed is free of contamination. Additionally, analytics can provide feedback as I adjust variables in my extraction process resulting in optimized methods. Without analytics I am forced to use very rudimentary methods, such as mass yield, to monitor my process. Mass alone tells me how much crude oil is extracted, but says nothing about the purity or efficiency of my extraction process. By applying plant biochemistry to my cultivation through the use of analytics I could start hunting for specific phenotypes within cultivars that provide elevated levels of specific cannabinoids like CBC or THCV. Taken further, technologies like tissue culturing could rapidly iterate this hunting process6. Certainly, one of the most compelling aspects of cannabinoid therapeutics is the ability to harness the unique polypharmacology of various cannabis cultivars where multiple bioactive compounds are acting on multiple targets7. To eschew the more traditional “silver bullet” pharmaceutical approach a firm understanding of both human and plant biochemistry tied directly to well characterized and consistently processed extracts is required. When all of these pillars are joined effectively we can fully characterize our unique cannabis raw material with targeted cannabinoid and terpene ratios, optimize an extraction process to ensure no loss of desirable bioactive compounds, compare our extracted product back to its source and ensure we are delivering a safe, consistent, “nature identical” extract to use in products with predictable efficacies.

Using these tools, we can confidently set about the task of processing safe, reliable and well characterized cannabis extracts for the development of world class products.


[1] Sweeney, C. “Goal-Oriented Extraction Processes.” Cannabis Science and Technology, vol 1, 2018, pp 54-57.

[2] Russo, E. B. “Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects.” British Journal of Pharmacology, vol. 163, no. 7, 2011, pp. 1344–1364.

[3] Giese, Matthew W., et al. “Method for the Analysis of Cannabinoids and Terpenes in Cannabis.” Journal of AOAC International, vol. 98, no. 6, 2015, pp. 1503–1522.

[4] Gul W., et al. “Determination of 11 Cannabinoids in Biomass and Extracts of Different Varieties of Cannabis Using high-Performance Liquid Chromatography.” Journal of AOAC International, vol. 98, 2015, pp. 1523-1528.

[5] Mudge, E. M., et al. “Leaner and Greener Analysis of Cannabinoids.” Analytical and Bioanalytical Chemistry, vol. 409, 2017, pp. 3153-3163.

[6] Biros, A. G., Jones, H. “Applications for Tissue Culture in Cannabis Growing: Part 1.” Cannabis Industry Journal, 13 Apr. 2017, www.cannabisindustryjournal.com/feature_article/applications-for-tissue-culture-in-cannabis-growing-part-1/.

[7] Brodie, James S., et al. “Polypharmacology Shakes Hands with Complex Aetiopathology.” Trends in Pharmacological Sciences, vol. 36, no. 12, 2015, pp. 802–821.