Two main issues were addressed during the studies reported herein. First, rigorous evidence for ketene formation during vaping was obtained via the use of an isotopicallylabeled acetate precursor. Second, ketene formation was shown to be feasible at common vaping temperature settings. Moreover, under anaerobic conditions, ketene formation was inhibited, demonstrating that the role of oxygen and hydroxyl radicals should be accounted for when investigating the mechanism of ketene formation. In addition, we found that ketene formation was not limited to molecules containing a phenyl acetate substructure. These findings show that theoretical models based on anaerobic pyrolysis studies may provide an insufficient estimate of the thermal oxidation chemistry that is possible under real world vaping and dabbing conditions. Further investigations into the scope of ketene formation from additional ester-containing flavorant additives is ongoing in our laboratories and will be reported in due course. prepared, the nail was heated to 378 °C (or 287 ⁰C), within the range of temperatures at which cannabis consumers typically dab. All flow rate values and puff durations were the same as previously described by us. After aerosol generation and collection over ~10 min using a CSM-STEP smoking machine, the solution was removed from the impinger and transferred to an NMR tube and immediately run on the Bruker Avance III 400 MHz NMR spectrometer. Additional trials were performed, and samples were run on the high-resolution quadrupole mass spectrometer for analysis. The samples were diluted with MeOH Anaerobic dabbing experimental setup. A Cole-Palmer glove bag (37"x37"x25") was used for all anaerobic experiments. The glove bag contained the electronic nail used in previous dabbing experiments, the dabbing glassware, and the compound of interest (for this experiment ethyl acetate or geranyl acetate was used). Three different lines were connected and sealed to the glove bag. One end of the bag was connected to the fume hood air line as well as another connection to an ultra-pure N 2 gas cylinder so switchover could occur without breaking the seal on the system. The other side of the glove bag was connected to the fume hood vacuum. Initial pressurization of the bag was achieved by closing the front zipper on the bag and taping the gas lines to ensure a proper seal. Air was allowed to flow into the bag at 2 PSI until the bag was inflated to a suitable working size. After a 5 min equilibration period the e-nail was turned on and allowed to heat to 378 °C. Once the desired temperature had been reached by the quartz surface (e-nail), 500 ul of ethyl acetate was administered onto the nail. The aerosol was pulled into an impinger containing the same solvent ratio as described in the section above. After 5 min the impinger was disconnected from the system and the solvent transferred to an NMR tube for analysis. After the initial samples were collected under normal atmospheric conditions, the air line was turned off and the ultra-pure nitrogen line was opened up and allowed to flow into the bag at 2 PSI while the residual air was pulled out via the fume hood vacuum at the same rate. The system was allowed to normalize to anaerobic conditions (0.0% O2 as measured by the Vzmcov 4 in 1 gas detector). Once optimal conditions were obtained the vacuum was turned off and the same dabbing experiment was again conducted under N 2 . Analysis of the impinger solvent system via NMR was again performed.