Real-Time Aerosol Mass Spectral Characterization of Aerosols Generated by an Electronic Nicotine Delivery System (ENDS) and Aerosolization of Surrogate E-Liquids as a Function of Humectant Composition and Heating Power

Yue Zhang, JIN YAN, Nicolas Aliaga Buchenau, Manjula Canagaratna, Caz Nichols, Michelle McCombs, Timothy Fennell, Elena Mishina, Samanthan Reilly, Marcella Ferlito, Kamau Peters, Jonathan Thornburg, Jason Surratt, University of North Carolina at Chapel Hill

     Abstract Number: 714
     Working Group: Aerosol Chemistry

Abstract
Electronic nicotine delivery systems (ENDS) heat and aerosolize e-liquids, generating a chemical mixture mainly composed oRf propylene glycol (PG), vegetable glycerin (VG), nicotine, and flavoring agents. The health risks associated with inhalation of aerosolized PG and VG mixtures and their thermal-degradation products remain a concern. Prior studies identified the chemical constituents of ENDS-derived aerosols using offline chemical characterization methods, which can be prone to artifacts. Real-time chemical composition of ENDS-derived aerosols can resolve the temporal distribution of aerosols to accurately quantify human exposure. In this study, we examined the real-time ENDS-derived aerosol composition using on-line analytical methods and compared it with data from offline chemical analyses.

We aerosolized e-liquids with five PG:VG volume fractions ranging from 0 to 100% with a KangerTech NRMesh atomizer device at power settings of 20, 60, and 100 Watts. The ENDS aerosols were 1) sampled by a real-time aerosol chemical speciation monitor (ACSM), and 2) collected onto Cambridge filter pads for offline chemical analysis using hydrophilic interaction liquid chromatography method coupled to high-resolution quadrupole time-of-flight mass spectrometry equipped with electrospray ionization (HILIC/ESI-HR-QTOFMS). The ACSM mass spectra contained tracer ions unique to PG and VG, and positive matrix factorization (PMF) methods estimated the fraction of PG and VG. Both on-line and offline analyses showed that ENDS-derived aerosols are dominated by VG due to its lower vapor pressure. Higher power was correlated with an enhanced ratio of ions with m/z > 104, consistent with elevated oligomer content from offline chemical analysis. A recent indoor air study using aerosol mass spectrometry with PMF methods found a factor associated with ENDS usage and had a similar profile to ENDS-derived aerosols in our study. These results highlight that the ACSM can be applied in situations where accurately quantifying the composition and temporal trend of ENDS aerosols are needed.