Residual Solvents

Residual solvents are leftover chemicals from the process used to extract cannabinoids and terpenes from the plant. The solvents are evaporated to prepare high-concentration oils and waxes. Sometimes, the evaporation process does not remove all of the solvent. Since these solvents are not safe for human consumption, it is important to verify their absence so you can guarantee you are providing a safe, chemical-free product.

Residual Solvents (FLORIDA)

MATRIX: Flowers/Plants, Derivative Products and Edibles
ANALYTES: 21 count

  • 1,1-Dichloroethene
  • 1,2-Dichloroethane
  • Acetone
  • Acetonitrile
  • Benzene
  • Butanes
  • Chloroform
  • Ethanol
  • Ethyl acetate
  • Ethyl ether
  • Ethylene oxide
  • Heptane
  • Hexane
  • Isopropyl Alcohol*
  • Methanol
  • Methylene Chloride
  • Pentane
  • Propane
  • Toluene
  • Total xylenes
  • Trichloroethylene

Residual Solvents (UTAH)

MATRIX: Flowers/Plants, Derivative Products and Edibles
ANALYTES: 41 count

  • 1,2 Dimethoxyethane
  • 1,4 Dioxane
  • 1-Butanol
  • 1-Pentanol
  • 1-Propanol
  • 2,2-dimethylbutane
  • 2,3-dimethylbutane
  • 2-Butanol
  • 2-Butanone
  • 2-Ethoxyethanol
  • 2-Methylpentane
  • 2-Propanol (IPA)
  • 2-methylbutane
  • 3-Methylpentane
  • Acetone
  • Acetonitrile
  • Benzene
  • Butane
  • Cumene
  • Cyclohexane
  • Dichloromethane
  • Dimethyl sulfoxide
  • Ethanol
  • Ethyl acetate
  • Ethyl ether
  • Ethylene Oxide
  • Ethylene glycol
  • Heptane
  • Hexane
  • Isopropyl acetate
  • Methanol
  • Methylpropane
  • N,N-dimethylacetamide
  • N,N-dimethylfromamide
  • Pentane
  • Propane
  • Pyridine
  • Sulfolane
  • Tetrahydrofuran
  • Toluene
  • Total Xylenes


MATRIX: Derivative Products
ANALYTES: 1 count

  • 2,3-butanedione



If you’re using one of the solvents above, there’s a chance that your product will test positive for residual matter. There’s a few potential reasons for this, starting with the type of product you’re producing. Products like shatter or wax, which have a smaller surface area, are generally harder to fully purge of solvents. These products require more time, heat and a deeper vacuum. Regardless of the type of product you’re producing, no two extraction runs are identical; slight variations in temperature, pressure, solvent profile and soak time can lead to a wide variety of test results.


Even the most refined and consistent extraction and evaporation process cannot account for minor differences between batches of naturally variable products. Even two runs from the same harvest can produce different results based on differences in the material used. The best way to avoid contamination is to constantly analyze and refine your extraction process. Then test your product with an accredited lab.

Why Test and Which Solvents to Test CANNABIS FOR

At ACS Laboratory, we test for 11 major solvents that could contaminate your product and put your customers at risk. For more information about our solvent testing, as well as other testing we have available, contact us today.

Residual solvents are chemicals that may be left over from the process of extracting cannabinoids and terpenes from cannabis. This extraction process is used to produce wax, oils and liquid concentrate products, which make up more than a quarter of the cannabis market today. The process is generally simple, but when trace amounts remain in the cannabis solution, residual solvents can cause minor to severe human health effects. Additionally, solvents can cause contamination by other means. During the extraction process, some solvents may pull out toxins such as pesticides, which can contaminate the finished product as well.

Cannabinoid Extraction Involves Solvents

Here’s how it works: Cannabis is dissolved in a liquid solvent, such as butane, which draws the cannabinoids and terpenes out of the plant. Then the solution is evaporated with heat under a vacuum to remove all the gas and leave a high-purity cannabis concentrate behind. Butane is a popular solvent because it doesn’t extract harmful compounds like pesticides and is one of the cleanest extractions possible.

But not all solvents are created equal. That’s why it’s important to learn about the different classes of cannabis solvents, the potential risks, and what you can do to make sure your finished product is free of contamination. Finally, it’s vital to test your product with an ISO accredited lab like ACS, to guarantee its safety and efficacy.


At ACS Laboratory, we currently test cannabis and hemp plant extracts for 11 solvents: Ethanol, N-Butane, Isopropanol, i-Butane, Chloroform, Methanol, Benzene, n-Pentane, Toluene, i-Pentane and Acetone. While there are no federal guidelines targeting solvents in cannabis specifically, the FDA does regulate solvents in consumer products and drugs. These regulations are based on 3 classifications:


Class 1 Solvents – Should be avoided. This category includes solvents that are known or suspected human carcinogens and/or environmental hazards.


Class 2 Solvents – Exposure to be limited. This classification includes solvents that are cancer causative agents of irreversible toxicity or suspected to cause significant but reversible toxicity.


Class 3 Solvents – Low toxic potential. This group is often recommended for cannabis and CBD extraction from hemp because it poses no known health risks to humans. 

The solvents below generally fall under one of the three classifications, which correspond to residual safety limits. When considering the solvent you’ll choose for extraction, it’s important to understand its federal classification first. The next step is to understand whether or not your state has guidelines for residual solvents in cannabis.


Benzene is a chemical that exists naturally from sources such as crude oil and coal, and is also a component of certain solvents. The FDA considers benzene a carcinogen and does not deem it safe at any level in consumer products. Benzene is a highly effective solvent, but can be life-threatening when ingested. If you decide to use benzene for your extraction method, you must take great care to ensure that it is fully evaporated or purged from the final product. Then test with an ISO accredited lab like ACS.


Inhalation of benzene either in the production phase or in the final product through oils, liquids or vaping cartridges can lead to serious risks to brain and immune function. Short-term illnesses include drowsiness and dizziness. High-level or extended exposure to benzene can also lead to diseases such as anemia and leukemia.

CLASS 2 SOLVENTS: Chloroform, Methanol, Toluene, n-Butane

Unlike benzene, Class 2 solvents can remain present in products as long as they don’t exceed the safety threshold. Residual solvent exposure limits are usually measured in parts per million (PPM) and can vary greatly from one chemical to the next. For cannabis, acceptable levels may also vary depending on whether you’re testing an inhalable product versus an edible or oil. These variations are based upon how the solvent interacts with heat or other chemicals when creating the product. Understanding your state’s safety thresholds and latest guidelines can be confusing, which is why ACS is always up-to-date with the federal and state standards.
Contact us today to learn more.  


Long-term exposure to high levels of Class 2 solvents like chloroform can lead to liver and kidney damage. Methanol exposure can lead to diseases of the optical nerve like blindness. At high levels, methanol can also be fatal. Toluene presents a risk because it’s a precursor of benzene. Exposure can cause fatigue, lightheadedness and confusion in low dosages. At high dosages, toluene can cause memory loss, seizures and coma.


Unlike the aforementioned solvents, N-Butane is generally regarded as safe (GRAS), according to the Food and Drug Administration (FDA). This form of butane has a low boiling point that, when combined with other chemical compounds like propane, can help remove residual solvents. On its own, low levels of N-Butane are safe and create fewer greenhouse gases compared to other chemical compounds; however, inhaled butanes in general can cause drowsiness and cardiac arrhythmias. 


Because regulations vary across states, the most important step you can take is to test your product for all known solvents with an accredited lab. At ACS, we are on top of Florida’s ever-evolving guidelines, but we also look at other states to help inform our analysis.
For example, California banned chloroform, methanol and toluene because they have deemed these solvents as carcinogenic and toxic to the reproductive system. It’s important to understand California’s stance, while also acknowledging that most states consider Class 2 solvents safe at low levels. 

CLASS 3 SOLVENTS: Ethanol, n-Pentane, Acetone, Isopropanol
(includes unclassified solvents: i-Butane, i-pentane)

Class 3 and unclassified solvents are generally considered safe and acceptable in larger doses than their Class 2 counterparts. For example, Washington state permits 50 PPM of chloroform to be present in a cannabis product, whereas it permits 1,000 PPM of ethanol. At the same time, California sees things differently. California includes ethanol as a chemical with potentially harmful health side effects.


As a whole, the side effects of Class 3 solvents are irritation of eyes and nose or intensified intoxication if inhaled directly. If ingested, something like acetone can also cause neurological damage. Overall, the process in which Class 3 solvents would be used to extract cannabinoids and terpenes does not produce the high levels of exposure that would be considered harmful to people. Therefore, these types of solvents are considered the safest for your consumers.


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