After extraction and prior to cannabinoid isolation, (whether chromatography, crystallization or some other means), distillation should definitely be performed. Consider that your crude extract typically might be anywhere from 55% to 75% total cannabinoid in the feed, plus lighter components of terpenes, solvents and water (2-7%), with the remainder being heavier components such as lipids, sterols, chlorophyll, fatty acids, salts, sugars, and heavy waxes, (18-43%). Also consider that distillation, (which does not introduce any additional chemicals), will result in a clear yellow product distillate stream of between 80 to 95% purity cannabinoid and that a dark waste residue steam of 18-43% of unwanted feed material gets removed in the process! All this unwanted non-cannabinoid has no business being brought into the isolation operation, especially when it can be so easily removed beforehand. Leaving this heavy portion in taxes the isolation process resulting in less product purity and significantly lower yield of available product. In the case of chromatography, this waste product also fouls the chromatography media faster, resulting in shortened life of this expensive material. Also, the viewpoint that distillation is best omitted because it removes the “full spectrum, entourage” components is moot because when the product undergoes an isolation process, such components are definitely removed by definition of “isolation”. Terpenes and other components that one may want to include in the product can be added later, depending on the type of product that is being made.
By mixing the CBD distillate with a solvent the material becomes dissolved. As this solution is slowly chilled, the CBD will begin to become supersaturated and crystallize. Crystals are highly organized structures and usually are at their lowest energy state when they are comprised of identical homogeneous units. Therefore, under the right conditions as the CBD molecules, (the most abundant component in the solution) begin to fall into the crystal lattices, (think perfectly played Tetris) it will eject impurities, also known as “inclusions”, which simply do not fit into the lattice Everything gets kicked out of the growing lattice, including THC. Once crystals are formed and filtered away from the remaining liquid, some impurities remain on the surface of the crystals, contaminating them. To remove this, the crystal product is washed with fresh solvent prior to drying.
Most customers utilize heptane and/or pentane for this process, procured in the highest purity available. Heptane (C-7) is often considered preferable due to its greater boiling point (98.4°C) when compared to pentane (C-5) with its BP being 36.1°C. Highly flammable solvents like these are particularly much more dangerous if their BP is low like pentane’s is. Hexane (C-6) is typically avoided, partially due to its ability to hold a static charge, creating higher fire risk as it is transferred through vessels and piping.
If the composition of your high purity CBD end product being sold has greater than 0.3% THC in it, it must first be further treated to reduce the level to less than 0.3%. However, if some portion of your end products are different, such as edibles, beverages, etc., the cannabinoids will be mixed into other ingredients, (flour, sugar, water, etc.) which are normally much greater in percentage than total cannabinoids. Consider for example, a cookie recipe that calls for CBD distillate (not isolate) to be mixed in so as to account for 5% of the total finished cookie weight. If the distillate used contained had contained 90% CBD and 4% THC, the resulting cookies would contain 4.5% CBD and 0.2% THC, meeting the required specifications. The question before company management becomes: For the cookie product line, is it worth it to further purify that distillate by isolation prior to blending it into the cookie dough?
Not necessarily, this is dependent on your process and your ultimate use of the isolate. Purity of your starting material, mixing, seeding, as well as other factors all go into the particle size and particle size distribution of your isolate. Particle size and size distribution can be controlled by adjustment of parameters during crystallization.
This can vary greatly, but for example, it is typical for a > 85 % purity CBD distillate to become > 99.5% purity CBD in an isolate, containing from less than 0.01 % down to an undetectable amount of THC. The yield, i.e., the amount of total available CBD in the distillate which ends up in the final isolated product, has been found to vary anywhere from 65% to 85% (from 15 to 35% yield loss). Higher quality starting material and higher operator skill will lead to greater yield and purity.
Yes. Pope has developed standardized system designs incorporating both crystallizing reactors and Nutsche filter-dryers plus peripheral components, (the same methodology utilized in pharmaceuticals and fine chemicals), offering excellent control of processing parameters and delivering highest purity, yield and cannabinoid manufacturing efficiency. The standardized system designs allow shortened lead times of this equipment. In addition, we are often requested to provide customized isolation, filtering, drying and other equipment within the cannabinoid processing space as well as for food and pharmaceutical manufacturers world-wide. Such custom work is a strong point with Pope; we enjoy the challenge and are “Solution Driven”.