Residual solvents

Most hemp extraction uses a solvent. Ethanol and light hydrocarbons such as butane and propane dissolve cannabinoids efficiently, and the solvent is then evaporated or purged under vacuum. Whatever does not leave stays in the oil as a residual solvent (Molecules 2022). Supercritical carbon dioxide extraction avoids the issue because CO2 returns to gas at atmospheric pressure, though CO2 extracts are often winterized in ethanol afterward.

Labs measure residual solvents with headspace gas chromatography, which heats a sealed sample so volatile compounds enter the air above it and can be sampled and separated. Results are reported in parts per million for each solvent on the panel.

There is no single federal limit for hemp products. A 2022 comparison of state cannabis regulations found that allowable solvent limits and the list of solvents tested vary widely between states (Jameson 2022), and a 2026 review reached the same conclusion for the broader contaminant panel (Cannabis Cannabinoid Res 2026). Many labs borrow limits from pharmaceutical standards for solvent classes.

A certificate of analysis should list the solvents tested, the limit for each and the result. Pass alone is not informative without the panel.