Houdini Lab

The Evolution of Cannabis Ethanol Extraction Methods

Ethanol has been used for centuries to extract perfumes, culinary colors and flavors, medicinal bases, and essential oils. The FDA has determined that consumer items made with food-grade ethanol are safe for human consumption, whereas other alcohols are not. Heavily used after water. It is also the least harmful alcohol, making it a popular solvent in consumer goods. With all of these benefits, it’s no surprise that ethanol is still one of the most extensively utilized solvents in the cannabis industry.

Ethanol is a polar solvent with nonpolar characteristics. The hydroxyl group attracts polar and ionic molecules, while the ethyl group draws nonpolar molecules. The hydroxyl group of ethanol and water.


Due to their acidic hydroxyl groups, THCA and CBDA are both polar molecules. So they both extract well with ethanol at ambient temperature. During most ethanol extractions, chlorophyll easily coextracts with the cannabinoids. This is why current ethanol extracts labeled Rick Simpson oil (RSO) are dark green in color and contain 40–60 percent ethanol. Methodology improvements have optimized cannabis extraction while excluding chlorophyll and waxes.


Early Years Methods



This method has been utilized for centuries and is termed “traditional” for phytochemical production (2).




Cannabis is steeped in ethanol.

Soil-solvent solutions are separated by filtering plant material.

The solvent is removed via rotating evaporation or falling film evaporation. This yields a plant extract.

The solute-solvent solution can be used to extract products such as alcohol-based tinctures.




Method ease

Quick extraction


Can be used at a

a lot




Target compound extraction with little control

Long extraction times depend on the input material, ethanol proof, and extraction temperature.

Lack of control over temperature and hence polarity of solvent in cannabis extraction results in chlorophyll, water, and other chemicals in the extract. This approach yields an extract that is not pure cannabinoids.

Extraction of Soxhlets


That’s why it’s called “traditional” medicinal preparation.



Plant material, such as cannabis, is put into a column between an ethanol boiling flask and a


The ethanol is heated to create a vapor that interacts with the plant material to extract it. The resultant solution contains solvent and substances soluble in ethanol at vapor temperature.

Soak the ethanol-extract in the boiling flask.



Method ease

The plant material is kept separate from the ethanol-extract solution, removing the need to filter it.

Quick extraction




Selectivity is poor.


Like maceration, the result is a tainted cannabis extract.

New Developments

Extraction of Ethanol


This approach has evolved over the last decade to improve ethanol selectivity and cannabinoid extraction.

a way (5)


Plant material is placed in an extraction chamber in a mesh bag or basket.

The solute is removed with the ethanol that runs through the plant material.

The ethanol-extract solution is then poured into a collection tank for further processing.

Rotary or falling film evaporation is used to evaporate the solvent.

The extract can then be utilized to make products or distilled to increase cannabinoid purity.



Enhanced solvent selectivity for a purer cannabis extract





Solubility and yield decreased

Costly equipment

Energy intensive solvent chilling

Centrifuge Liquid-Solid Mix and Cold Ethanol Extraction


Common technique in cannabis and hemp ethanol



Plant material is uniformly ground.

Plant material is inserted in a mesh bag and spun in a centrifuge.

The ethanol is then added to the centrifuge chamber to soak the cannabis.

The centrifuge is started and churns like a washing machine, mixing the solvent and plant material.

After extraction, the extracted solution is poured into a collection jar.

As the solution evaporates, the final extract is complete and ready for formulation.

Pros Quick extraction

Solubility improvement

The extraction separates the liquid and solid, avoiding the need for filtration.


Solubility and yield decreased

Costly equipment

Energy intensive solvent chilling

Equipment maintenance—ethanol can quickly wear out bearings in high-speed centrifuges.

Changing the plant material in the centrifuge is time consuming.

Note: As the process scales up, the yield decreases due to more ethanol being utilized and lingering in the plant material. This decreases yield and increases evaporation processing time.


Many years have passed since isopropyl or methanol were used in plant extraction. Unlike ethanol, isopropyl alcohol and methanol are harmful to breath or ingest at far lower amounts than ethanol (6). Methanol has a lower boiling point and so is less polar. Methanol, being less polar than ethanol, extracts less THCA and CBDA. Because isopropyl alcohol has a greater boiling point and polarity, it extracts more cannabinoids faster, but it also extracts more chlorophyll. This includes the expense of the solvent, the capacity to remove all leftover solvent to reduce customer danger, and post-processing time and procedures. These alternative alcohols are excellent candidates for distillation refinement. Cannabinoid purity is not required in the crude form when using wiped or thin-film distillation.