What is CO2 oil?
As cannabis connoisseurs seek higher purity and higher quality, previously obscure extraction methods have become fashionable for making different and better cannabis concentrates. One such method is supercritical fluid extraction, used to make what is known as " CO 2 oil". As the dabber becomes more terpene savvy, extraction artists are using methods that allow for higher terpene content, with CO 2 supercritical fluid extraction at the forefront of cannabis extraction.

Supercritical fluid extraction (SFE) takes advantage of the strange properties of a gas that is compressed beyond its "critical point". Carbon dioxide (CO 2) is the most commonly used gas because its critical point can be reached at around 90°F and is cool enough that the delicate plant terpenes and cannabinoids are not deactivated. In addition, the shape of the CO 2 molecule allows it to be used as a non-polar solvent, with butane or hexane being non-polar.

A supercritical fluid behaves like both a liquid and a gas. It diffuses through solids like a gas, and dissolves compounds like a liquid. The fluid has almost no surface tension, so it easily penetrates the cuticle of cannabis hairs, thus dissolving all the oils in its path. To see what supercritical CO 2 (scCO 2) looks like, go to this video. As the temperature increases, the CO2 becomes supercritical at 0:35 as the solution becomes cloudy and opaque.

The solubility of scCO 2 varies with pressure. This allows the extractor to use different vessels at different pressures to separate extracts with different compositions. The bearing pressure allows for the complete separation of terpenes and cannabinoids and all substances in between.

Supercritical carbon dioxide flows through the extraction vessel at a certain temperature and pressure, and after collecting the available terpenes, waxes and cannabinoids, the solution enters the separator vessel (at different temperatures and pressures) which can be used to change the composition of the separator. Extraction. After extraction is complete, the pressure drops allowing the CO 2 to be easily evaporated and recovered.

As a general rule, SFE extracts using scCO 2 have a higher terpene content than typical BHO dab. although BHO may have 0.5% to 3.5% terpenes (depending on how it is prepared), the consumed CO 2 oil mass is typically about 8 -10% terpenes. A study from the University of Udine, Italy, conducted experiments on SFE to extract aromatic compounds from industrial hemp for use in cosmetics. They looked at terpenes, rather than cannabinoids, and found that heavier sesquiterpenes such as stigmasterene and andrographolene were less soluble at lower pressures. sfe allowed the extractor to vary the terpene content depending on the settings.

Interestingly, researchers from Leiden University in the Netherlands found THC to be the least soluble cannabinoid in scCO 2, followed by CBG and CBD, with CBN having the highest solubility. The highest THC concentration they obtained in the extract was 50%, but they started using Bedrocan cannabis strains that contained only 13% THC.

Researchers at the University of Basque Country (Spain) used really high THC producing strains (Amnesia, AK-47, Somango and Critical) and tried different solvent systems. By using a supercritical fluid mixture of CO 2 and ethanol, they were able to extract about 95% of the available tetrahydrocannabinol in the first run.

Methods not yet publicly available in the medical marijuana industry have been optimized for making cannabis extracts. Because SFE extracts more terpenes, the extract is typically less viscous and more fluid than BHO, making it ideal for vaporization pens.

In addition to the selective advantage offered by SFE (the ability to select extracts with different components from the same raw material), CO 2 is a "green solvent", unlike petroleum derivatives such as butane or hexane.