Temperature Control Minimizes Wax-Derived Alkane Carryover in Hydrocarbon Cannabis Extraction

Cannabis produces a diverse array of nonpolar metabolites, including cannabinoids and terpenes, making nonpolar hydrocarbon solvents well-suited for extracting inhalable concentrates. In practice, these extracts also contain a poorly characterized nonpolar fraction colloquially termed "fats and waxes," which can be removed by winterization. To clarify the composition and process dependence of this fraction, we examined n-butane extractions of two cannabis varieties (GMO and Oreoz) across the industrially relevant temperature range of -46 °C to -9 °C. Using GC×GC-TOF-MS/FID, we identified long-chain n-alkanes (C₂₂-C₃₁), consistent with epicuticular wax constituents, as major components whose abundance increases systematically with extraction temperature, while total cannabinoids and quantified volatile aroma compounds remain relatively constant over the same range. Viscosity measurements show only modest changes with wax loading, indicating limited impact on bulk rheology at the concentrations studied. Aerosol capture experiments demonstrate that these n-alkanes transfer efficiently into the mainstream aerosol and that aerosol wax levels track their concentrations in the starting high-terpene extract with an approximately linear relationship. Lowering the extraction temperature reduces both wax content in the oil and the corresponding wax dose in the aerosol, with up to ≈3-fold reductions depending on cultivar. These results establish extraction temperature as a practical control point for minimizing epicuticular wax coextraction in hydrocarbon-derived cannabis concentrates, demonstrating that lower temperatures selectively reduce long-chain n-alkane content while preserving cannabinoid potency and native-like aroma profiles. The efficient transfer of these alkanes into mainstream aerosol further indicates that extraction conditions directly influence consumer inhalation exposure to wax-derived constituents.