Steps to CO2 Extraction THC

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Converting Cannabis Compounds (or not)

A raw marijuana plant contains several important compounds, and carefully controlled extraction methods can unlock others like THC. Many of these compounds change as they are heated. For example, cannabis contains THC in its acid form, THCa (non-psychoactive). When the plant material is exposed to heat, the THCa converts to THC.

A very specific heat and time ratio is critical, not only to convert THCa to THC, but also to prevent the THC from changing to a different compound. That’s why Apeks Supercritical has engineered thermally sensitive COcannabis extraction systems using lower, plant-friendly temperatures for cold separation processing. Cold separation protects plant oils by never exposing them to temperature higher than the extraction temperatures, thereby protecting the volatile oils and terpenes, as well as retaining more THCa. Depending on the end products, processors may use the oils containing THCa (which offers its own therapeutic benefits) or convert it to THC.

To learn more about cold separation, watch this short video:

CO2 Cannabis Extraction

As described above, the conversion of THCa to THC requires heat. This is a chemical process called decarboxylation. The best way to get the highest yield through COcannabis extraction is to decarboxylate it first. Typically, processors use ovens for this task. Once decarboxylated and dried, the material is ground up into a coffee-ground consistency. Watch a video of this process here:

The ground-up material is loaded into the machine and the processor/machine operator starts the extraction run. Unlike a subcritical extraction (low pressure, low temperature), a supercritical extraction method (high pressure, high temperature) extracts everything from the plant, including some undesirable elements like fats, waxes, and lipids. These need to be removed via a process called winterization so that only pure oil remains.

Steps to Winterization

STEP ONE: The extract containing fats and waxes (a sludgy crude oil that looks like runny peanut butter) is mixed with 200-proof alcohol, and put in an industrial freezer overnight. The next day, the mixture is filtered through a funnel, trapping the undesirable elements onto filter paper. The mixture can be run through the filter several times as needed. 

STEP TWO: Remove the alcohol. This is done by gently warming the oil extract using a rotary evaporating machine. Alcohol’s boiling point is different from the oil’s, so it simply evaporates out of the oil. The alcohol is recovered and can be reused in the future. 

STEP THREE (optional): Once the oil is free of alcohol and plant wax, it can be further refined to separate individual compounds like THC using short path or fractional distillation processes.

All Apeks customers are eligible for one free winterization class! Watch a video of the class above.

Short Path Distillation: Isolating THC

Separating the individual compounds of the cannabis oil extract is a labor intensive and specialized process known as short path distillation, or fractional distillation. Each compound of the cannabis oil boils at a different temperature, so when the oil is heated, the compounds are siphoned off as they reach their particular boiling point. The whole process requires specialized equipment and takes some time, so it’s not for the faint of heart! Distilling the individual compounds creates “isolates” – oil containing one compound for medicines targeting specific ailments. There is also a strong case for maintaining all of the compounds in the oil (see the entourage effect described below).

Read more about Short Path Distillation here.

The Entourage Effect

The current thinking is that the oil is even more therapeutic when all the compounds are included; the whole plant has so many beneficial compounds, that together, they offer the greatest benefit.

Advantages of CO2 Extraction: Key Takeaway

With the proper products and training, processors can extract specific compounds like THC. Understanding boiling points of each compound is critical. Extraction processes takes time, money, and dedication but is well worth it!  And with an Apeks Supercritical system utilizing cold separation to preserve the terpenes and other compounds, you can join other customers producing award-winning cannabis oils!


COextracted material is free of residual solvents. Nothing is left behind once the extraction is over since the carbon dioxide bubbles away, leaving no trace in the end product.


​Comparing CO2 cannabis extraction to butane or propane? Don’t forget to include the facility costs for processing with a compressed flammable gas.

Learn More


Other extraction solvents, such as hydrocarbon-based propellants like propane and butane, hexane and pentane, or ethanol/alcohol mixtures, require additional distillation or purging beyond the supercritical COextraction process to separate the solvent from the extracted oil. Carbon dioxide has a very low boiling temperature and wants to be a gas at room temperature, so it naturally separates from the extracted oil, without additional distillation or purging.


CO2 extraction can be done at temperatures native to the plant, minimizing thermal degradation of the plant material and the extracted oil.


 Carbon dioxide is readily available and widely used throughout a number of industries. Apeks supercritical CO2 extraction systems recirculate and subsequently recover 95% of the carbon dioxide used in each extraction.

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