Residual solvent testing

Residual solvent testing detects and quantifies volatile organic compounds remaining in cannabis extracts, concentrates, and manufactured products after solvent-based extraction (butane or propane hash oil, CO₂, ethanol) and post-processing purges. California's DCC regulates 20 solvents split into two categories aligned with ICH Q3C pharmaceutical classes. Category I compounds (limited to ~1 ppm) include benzene, chloroform, ethylene oxide, methylene chloride, trichloroethylene, and 1,2-dichloroethane — known or suspected carcinogens. Category II compounds have higher ppm action limits: butane and propane (1,000 ppm), pentane, heptane, ethanol, isopropanol, ethyl acetate, acetone (1,000 ppm); hexane (60 ppm); acetonitrile (80 ppm); toluene (180 ppm); xylenes (430 ppm); methanol (600 ppm). The analytical standard is Headspace Gas Chromatography (HS-GC) coupled to Flame Ionization Detection or Mass Spectrometry, with samples sealed in headspace vials heated at 80–140°C. Why it matters: benzene is a confirmed human carcinogen causing leukemia; hexane causes peripheral neuropathy; poor-grade "camping fuel" butane contains benzene and pentane contaminants. Because extracts are vaporized or dabbed at high temperatures, solvents reach the bloodstream directly. → See also: Testing lab, Extraction technician, Manufacturer