The Risks and Rewards of Different Cannabis Separation Techniques

During the planning stages of a cannabis extraction operation, it is important to understand and appreciate the various separatory techniques and pieces of equipment needed for the job.

Column chromatography, for instance, was invented by Russian botanist Mikhail Tsvet in the late 18^th century. Since then, it has been employed rigorously to separate compounds using instruments such as high-pressure liquid chromatography (HPLC), gas chromatography (GC) and centrifugal partition chromatography (CPC). Within a cannabis analytical laboratory, HPLC and GC are used to identify and quantify cannabinoids and terpenoids in flower biomass, oil extracts, and infused products. CPC is fairly new to the cannabis industry but is showing great promise for Δ9-THC remediation, minor cannabinoid isolation, and contaminant removal.

Although the techniques mentioned above have several uses in many industries, there are caveats one must observe. In the cannabis/hemp processing lab, distillation is frequently utilized to create a more refined extract (broad spectrum), fractionate, and collect terpenoids, or to remove contaminants from cannabis oil, such as heavy metals. Listed below are several methods of distillation employed while processing cannabinoid oil extracts:

Distillation method	Type of cannabis lab employing the method	Pros	Cons
Short path	High-THC cannabis extractors (consumer facing products such as vape cartridges, tinctures, edibles)	Inexpensive Fractionated products Small footprint Customizable	Low throughput Limited scalability High degree of operator input and experience
Wiped film	Industrial hemp processors (creating compliant distillate as an ingredient)	High throughput Semi-automation Even heat transfer	Expensive Multiple passes needed to produce high quality product Darker color of final product
Spinning band	Both high-THC extractors and industrial hemp processors	High level of automation Data logging Easy maintenance  Limited operator attendance	Expensive High level of processing of input material Slow distillation rate Complex setup
Multi-stage thin film	Industrial hemp processors	High throughput Continuous feed Several pump stages for limited passes High product yield	Expensive Limited fractionation capabilities  Limited terpene retention

More than a few equipment manufacturers make ambitious claims on what their equipment can accomplish in terms of separating chemical compounds, throughput, and yield. I cannot stress enough how important it is to vet the manufacturers thoroughly. In addition to your due diligence, it is advised to request a customer list, so you can speak with people using the equipment in the industry who have acquired real time data.

The remediation of bulk ingredient Δ9-THC is also a hot area to explore many different separation methods and new technologies. In the past, flash chromatography and CPC have shown excellent results. However, the biggest complaint has been consumable cost and throughput. Many new technologies have since come online and many companies have now employed several scientists to research and develop in-house methods.

But beware of the “glitters like gold” scenarios when it comes to remediation and be certain of your strategy before embarking on your journey. There is nothing wrong with experimenting using catalysts with your extract if you realize the time, money, and repetition needed to produce a robust method. It would be beneficial to work into your capital expenditure budget or partnering with a company to perform services for you.

Cannabinoid extraction is delicate and highly dependent upon many factors such as pressure, temperature, and solvent choice. Considering the extraction method and tunability of the solvent, you can bring along other constituents with the desired oil product during extraction. Writing in Extraction Magazine, Dr John McKay covered it in an interesting perspective relating extraction and solvent tunability to conducting an orchestra.

“When I talk about tunability, I like to use an analogy of an orchestra. The conductor (method developer) can organize the musicians (cannabis components) and ask them to leave the room (extraction) in sections upon request. If ethanol, which has less tunability at room temperature, is used as the extraction solvent, the conductor could only ask the musicians to leave the room altogether. With CO₂, however, the conductor could ask the string section to leave the room, then the percussion, then the brass section and so on.”

If pesticides are used during cultivation or the soil medium is laden with heavy metals, these contaminants can carry over and concentrate within your desired product, prompting a remediation step downstream. Distillation proves to be an effective method of separation from heavy metals where this is not so easily achieved with other contaminants, such as pesticides. However, the use of CPC and its level of selectivity makes it an effective choice for pesticide removal from oil.

With compliance, quality, and safety driving the cannabis consumer market, one must consider all these methods to have on hand. As separation is vital to the removal of THC from bulk CBD/CBG oil products and the removal of unwanted contaminants in oil extracts, it is imperative that cannabis companies understand these processes, hire the appropriate technical knowledge base to carry out these methods, and help develop new, improved technologies for the future.