Residual Solvents
Cannabis extractions are made by a process that gathers the desirable chemicals from the cannabis plant while leaving behind the undesirable chemicals and plant material. Cannabis concentrates are extremely popular, especially with increasingly sophisticated consumers. Concentrates are being added to everything! Tinctures, coffee, sweets, cookies, savory crackers, beer, soda’s, fruit beverages, lotions, and even suppositories. Cannabis concentrates are producing oils that can be as high as 85% tetrahydrocannabinol (THC). 
What are residual solvents?
Residual solvents are used during the extraction process to pull the desirable chemicals out of the plant material. In many cases, these solvents must be removed by further processing as they can be harmful or even toxic if consumed. There are solventless extractions, such as CO2 and water and there are non-volatile solvents such as ethanol. Even solventless extractions however can result in residual solvents remaining in the final concentrated oil. Residual solvent analysis is a critical element of cannabis testing to help ensure that there are no toxic or harmful solvents remaining in the final product.
Typically solvents (and processing chemicals) are classified by FDA in one of three classes:
- Class 1 - solvents that must not be used in the production of cannabis concentrates as they are known to be highly toxic or even carcinogens. Examples include: 1,2-Dichloroethane, Chlorofom1, Ethylene oxide, Methylene chloride, and Trichloroethylene
- Class 2 – solvents that can only be used under stringent controls and GMPs as they are still harmful if not handled or used correctly. Low levels are allowed in cannabis products but these levels can differ from State to State. Examples include: Acetone, Butane, Hexane, Methanol, and Propane.
- Class 3 - solvents with low toxic potential. Low levels are allowed in cannabis products but these levels can differ from State to State. Examples include: Ethanol, Isopropyl Alcohol.
Testing for Residual Solvents:
The best equipment for Residual Solvent testing is a GC/MS with a headspace analyzer. Cannabis samples are placed into a large sealed vial. The vapors of any residual solvents will naturally be released into the headspace of the vial, which are then analyzed by the GC/MS.
