Residual Solvents

Residual solvents are leftover extraction chemicals (butane, ethanol, propane, hexane) that remain in concentrate or vape product after processing. State-required COAs test for residual solvent levels in parts per million; safe products test well below state limits. High residual solvent levels indicate poor purging and are an immediate health concern.

Example: Residual solvents under 50 ppm — clean BHO.

Etymology: Standard chemistry vocabulary; applied to cannabis concentrates in mandated state testing.