Several methods currently utilized for the extraction of CBD and THC from cannabis extracts, including chromatography, extraction with organic solvents (e.g. pentane) and sub-and supercritical CO2 extraction. A newer technology based on membrane extraction has been reported by Green Sky Laboratories (Green Sky Labs, Poster Presentation, March 2018).

Extractions

In general, primary extraction processes which releases the cannabinoids from the plant matter use organic solvents (e.g. propane, butane, ethanol) and sub- and supercritical CO2, depending on the technique used the result is a mixture of cannabinoids and can also contain terpenes, lipids, waxes, flavonoids, and plant material including chlorophyll. While there are some recreational uses for these crude extracts, the vast majority of the existing and anticipated market is in high quality distillares and isolates. These products require post-extraction processing. This process usually starts with sequential distillation of the crude which removes a lot of the unwanted material but leaves the cannabinoid spectrum relatively untouched.

Chromatography

The only process widely used to generate either high purity THC and CBD (or other cannabinoids) from the plant extracts is chromatography. It is typically used as a final processing step with pre-processed material (to remove all components except cannabinoids) as the starting material, adding cost to the final pure products. Although the chromatography process is currently employed for cannabis extract purification, it suffers from various shortcomings which limit commercial viability at the levels needed to meet emerging market demand.

Chromatography is a labor-intensive process which can also suffer from incomplete purification (retention of residual impurities/undesired side-products). While larger variations of chromatography equipment is around, the overall process is not cost effective and is limited in scalability without incurring great expense. Chromatography also requires relatively pure cannabinoid material (e.g. terpenes and waxes removed) to improve efficiency and limit fouling of chromatography media (e.g. silica gel). Depending on the solvent system used, there are also cost concerns and safety concerns as some of the solvents needed for chromatography are toxic.

Affinity™

By contrast, Affinity™ can be used with crude extracts that are treated only to remove the heavy lipids and can be scaled to process at any throughput. Dilution of crude is done with water and ethanol and removal of the target cannabinoids from the Affinity™ nanotechnology is also done with mixtures of water and ethanol.