E-Cigarettes Generate Gas Phase Ions

Mass spectrometry (MS) evidence shows that electronic cigarettes (e-cigs) can directly emit gas phase ions at levels orders of magnitude greater than detected from typical ambient air or smoke from the mouthpiece of a traditional tobacco cigarette (t-cig). These ions, generated upon atomization of the e-liquid into an e-cig aerosol, are presumably inhaled by e-cig users. Emissions from disposable e-cigs were sampled at atmospheric pressure directly into a mass spectrometer without a conventional ion source. All four e-cigs produced mass spectra with high ion intensities, indicating that their aerosols were ion-rich upon exiting the mouthpieces. While multiple ionization pathways may contribute, atmospheric pressure thermospray ionization (APTSI) appeared to be the dominant pathway. The e-cig self-ionization process provides a direct method of aerosol analysis by mass spectrometry (MS) and eliminates the need for precollection and conventional MS ion sources. This finding has implications for e-cig user exposure that warrant further mechanistic and toxicological study.