Mile High Labs has developed a process utilizing food grade alcohol which produces the highest quality CBD extracts at a reasonable cost and with very high throughput.
Any effective extraction process involves the use of a solvent to remove target compounds from the botanical material. With a variety of solvents being used in the cannabis industry it is important to understand the tradeoffs associated with each. All solvents dissolve non-target materials to some extent and so some level of further processing is often used to clean up the extract. At Mile High Labs we use only pure ethyl alcohol while butane and CO2 are commonly used by other labs in the industry. Below, I will discuss the pros and cons of each of these solvents.
Butane has been widely used to extract cannabinoids and is certainly the most popular solvent for marijuana but is also quite common for hemp. It is a relatively non-polar solvent with a dielectric constant of 1.4, which means it will dissolve the cannabinoids and terpenes without also taking much chlorophyll, flavonoids or other non-target material. There are two technical drawbacks to using butane as a solvent, as with other non-polar solvents, it will extract undesirable wax which will need to be removed from the eluate in a process called winterization, and secondly, it is critical that the solvent and any other hydrocarbons present in the solvent are purged from the extract to a level that is safe for human consumption. Both of these processes add time and expense, but the health implications from improperly prepared butane extracts is most concerning. Butanes that are 99% pure are commonly used and may contain other alkanes including pentane and isopentane which have much higher boiling points than butane and can remain present in high concentrations after the butane has been purged. More alarming is that some of the butane available contains carcinogenic compounds such as benzene, which may be present in the final extract.
Many people prefer to use CO2 to avoid the potential health hazards associated with butane and it has a number of other advantages that make it a great choice for hemp extraction. Under high pressure and temperature, CO2 is exist in either a liquid or a supercritical phase. Near this point, the density of CO2 can be finely tuned and can be a very selective solvent which dissolves only the cannabinoids, terpenes and waxes. The waxes can then be fractioned off by decompressing the CO2 in stages thereby producing a substantially pure product which is consumer ready right out of the machine. The downside of CO2 is the cost, because of the pressures involved, the equipment for supercritical CO2 extraction is extremely expensive. The cost for a system that will have a reasonable throughput for the hemp industry is over a million dollars. Of course, this cost gets passed on to the customer, making CO2 products more expensive than other extracts.
Alcohol combines the lower cost of Butane with the food safety of CO2. Although all of the solvent is purged from the final product, even if trace amounts still remain, the product is completely safe for consumption. Because alcohol extractions can be done at standard temperature and pressure, we don't have the cost associated with the high pressure vessels of the CO2 apparatus. This means lower cost extractions and more cost competitive consumer products. Alcohol does have one drawback, being a relatively polar solvent with a dielectric constant of 24.3, it readily extracts chlorophyll, flavonoids and polar or water soluble compounds along with the cannabinoids and terpenes. Many alcohol extracts available on the market, like Rick Simpson Oil (RSO), appear dark green or black in color because of this. Here at Mile High Labs, we employ cutting edge filtration and molecular distillation equipment and techniques to remove all of these non-target materials from our extracts leaving a substantially pure product. Because we already perform these filtering and distilling steps in our process, it allows us to be unconcerned with introduction of undesirable compounds into our extract up front, which means we can be more aggressive in making sure we extract all of the valuable cannabinoids and terpenes from the botanical material, maximizing yield and minimizing waste.