Butane vs. Ethanol Extraction: The Complete Guide
There are many methods cannabis manufacturers use to manufacture the concentrates available in dispensaries today. Each method has its own advantages and disadvantages and contributes to what the final product looks, feels, tastes, and smells like.
Two prominent forms of extraction include butane extraction and ethanol extraction. And while these two methods can both create concentrated cannabis extracts that meet regulatory standards, there are several key differences in how they stack up against one another. This guide offers a closer look at butane vs. ethanol extraction, as well as the pros and cons of each method.
In this blog, you will learn:
What butane extraction is and how it works
What ethanol extraction is and how it works
The pros and cons of butane and ethanol extraction
How cannabis analysis labs test for residual solvents
What is butane extraction?
Butane extraction is a specific form of hydrocarbon extraction performed using butane as the primary solvent to draw compounds like phytocannabinoids and terpenes out of the cannabis plant material. Butane, a colorless gas with a faint odor, is a non-polar solvent, meaning it only binds with fat-soluble compounds. Butane is highly flammable, colorless, and easily liquified.
In butane extraction, the solvent is passed over the cannabis plant material, separating the resin-rich trichomes and other compounds, like lipids and waxes, along with it. The resulting mixture is then typically subjected to winterization, a refining process to separate unwanted fats and waxes from the phytocannabinoids and terpenes.
Once winterization is complete, the remaining butane evaporates off, leaving behind the concentrated extracts consumers can find in dispensaries. Butane’s low boiling point of -1°C (31℉) makes it very easy to remove residual traces of the solvent from the final product: All it takes is bringing the sample to room temperature, or maybe mildly heating the sample, for the remaining butane to evaporate off.
What is ethanol extraction?
Ethanol is a polar solvent used in cannabis extraction for its ability to safely and efficiently pull compounds from the plant material. Ethanol is a polar solvent that not only pulls phytocannabinoids and terpenes from plant material much like hydrocarbon extraction, but also water soluble compounds like chlorophyll.
Ethanol extraction can be performed either warm or cold. Warm ethanol extraction involves boiling the ethanol and dripping it through plant material, extracting out phytocannabinoids and terpenes in the process. This method is highly efficient and saves solvent, but generally damages the desired compounds while pulling a lot of unwanted material like lipids. However, cold ethanol extraction can be desirable because it preserves phytocannabinoids in their acidic forms, enabling the creation of THCA or CBDA products, for example.
Ethanol is often considered an environmentally friendly method, since ethanol can easily be reclaimed and reused in future extraction processes. However, ethanol extracts generally require additional steps of refinement and filtration after the extraction process is complete. There is also the possibility that ethanol extraction leaves trace amounts of solvent behind.
The major differences between butane and ethanol extraction
The differences between butane and ethanol affect both the extraction process and the final product that reaches the consumer.
Difference #1: Boiling points
Butane has a low boiling point of -1°C (31°F), which makes it a great option for preserving desired phytocannabinoids and terpenes profiles. As a result, BHO tends to have an intact terpene profile and higher concentrations of the target compounds. Ethanol’s comparatively high boiling point of 78.37°C (173.1℉) means phytocannabinoids and terpenes degrade when exposed to heat during the refining process. As a result, ethanol extracts tend to contain less of the target phytocannabinoid and do not have as complete a terpene profile, unless additional terpenes are added back in after the extraction process is complete.
Difference #2: Purity
Ethanol is amphiphilic, as it is both polar and non-polar in nature. This makes it effective for pulling out phytocannabinoids and terpenes, but also brings with it chlorophyll and other compounds that may not be desirable in the final product. Butane extraction is strictly non-polar, so water-soluble compounds are not extracted -- just phytocannabinoids and terpenes.
Difference #3: Refining process
While both butane and ethanol extraction yield high-quality products, ethanol products can sometimes require more labor to achieve.
The importance of testing cannabis extracts for butane or ethanol
The Food and Drug Administration (FDA) classifies both ethanol and butane as Class 3 solvents with low risk for acute or chronic toxicity in pharmaceutical manufacturing processes where the residual solvent left behind in a product is less than 5,000 parts per million (ppm), or 0.5 percent. The FDA also implies that residual solvents in this category should be limited to 0.5 percent through rigorous quality assurance and quality control programs.
Beyond these federal guidelines, various state cannabis laws mandate testing and set in place limits for residual solvents in cannabis extracts. In New Jersey, these limits are in line with the FDA guidelines. It is worth noting that while the FDA’s standards do not explicitly apply to cannabis, they are a good guideline and standard to follow.
Cannabis manufacturers must first demonstrate that their products meet state regulations before they can be sold in a dispensary. That is where third party cannabis analysis labs like True Labs for Cannabis come in. True Labs obtains samples of cannabis products to analyze and report a wide range of factors.
Included in these tests is a residual solvent analysis. Labs test for residual solvents using a process called Gas Chromatography/Mass Spectrometry (GC/MS). Using this process, the sample is converted into a gas, including any of the residual solvent present within. The gaseous particles are then carried in an inert gas and passed through a very thin layer of solid or viscous liquid particles. As they pass through this layer, a mass spectrometer analyzes the compounds and is able to identify and quantify the levels of residual solvents present in the sample. If these levels exceed legal limits, the sample must be quarantined and either remediated, which can be quite difficult to do, or destroyed.
Butane vs. ethanol extraction: Test both for residual solvents
Regardless of the extraction method you choose, extracts must be properly refined and free of higher than acceptable levels of residual butane or ethanol before the products go to market. Moreover, running afoul of state regulations is a costly mistake that could put a cannabis manufacturer out of business for good. Instead, it is important to work with a trusted cannabis analysis lab like True Labs for Cannabis, which extends comprehensive cannabis lab testing services to the New Jersey legal cannabis industry. When you want and need to know what is in your cannabis products, choose True Labs for Cannabis.