Chemical\nComposition of Aerosols from the E‑Cigarette\nVaping of Natural and Synthetic Cannabinoids

Vaping cannabinoids in electronic (e)-cigarette devices\nis rapidly\nincreasing in popularity, particularly among adolescents, although\nthe chemistry affecting the composition of the vape aerosol is not\nwell understood. This work investigates the formation of aerosol mass,\nbioactive hydroxyquinones, and harmful or potentially harmful carbonyls\nfrom the e-cigarette vaping of natural and synthetic cannabinoids\ne-liquids in propylene glycol and vegetable glycerin (PG/VG) solvent\nat a 50 mg/mL concentration in a commercial fourth-generation vaping\ndevice. The following cannabinoids were studied: cannabidiol (CBD),\n8,9-dihydrocannabidiol (H2CBD), 1,2,8,9-tetrahydrocannabidiol (H4CBD),\ncannabigerol (CBG), and cannabidiolic acid (CBDA). Quantification\nof analytes was performed using liquid chromatography coupled to accurate\nmass spectrometry. The addition of cannabinoids significantly increased\naerosol and carbonyl formation compared with the PG/VG solvent alone.\nAll cannabinoids in the study formed hydroxyquinones during vaping\n(up to ∼1% mass conversion) except for CBDA, which primarily\ndecarboxylated to CBD. Hydroxyquinone formation increased and carbonyl\nformation decreased, with a decreasing number of double bonds among\nCBD and its synthetic analogues (H2CBD and H4CBD). During the vaping\nprocess, ∼3–6% of the cannabinoid mass can be observed\nas carbonyls under the study conditions. Oxidation of the terpene\nmoiety on the cannabinoids is proposed as a major contributor to carbonyl\nformation. CBD produced significantly higher concentrations of formaldehyde,\nacetaldehyde, acrolein, diacetyl, and methylglyoxal compared with\nthe other cannabinoid samples. CBG produced significantly higher levels\nof acetone, methacrolein, and methylglyoxal. Conversion of CBD to\ntetrahydrocannabinol (THC) was not observed under the study conditions.\nThe chemical mechanism basis for these observations is discussed.\nCompared with other modalities of use for CBD and other cannabinoids,\nvaping has the potential to adversely impact human health by producing\nharmful products during the heated aerosolization process.