Diacetyl and Other Ketones in e-Cigarette Aerosols: Some Important Sources and Contributing Factors
Open Access
- 23 September 2021
- journal article
- research article
- Published by Frontiers Media SA in Frontiers in Chemistry
Abstract
Background: Concerns over the presence of the diketones 2,4 butanedione (DA) and 2,3 pentanedione (AP) in e-cigarettes arise from their potential to cause respiratory diseases. Their presence in e-liquids is a primary source, but they may potentially be generated by glycerol (VG) and propylene glycol (PG) when heated to produce aerosols. Factors leading to the presence of AP, DA and acetoin (AC) in e-cigarette aerosols were investigated. We quantified direct transfer from e-liquids, examined thermal degradation of major e-liquid constituents VG, PG and 1,3 propanediol (1,3 PD) and the potential for AC, AP and DA production from sugars and flavor additives when heated in e-cigarettes. Method: Transfers of AC, AP and DA from e-liquids to e-cigarette aerosols were quantified by comparing aerosol concentrations to e-liquid concentrations. Thermal generation from VG, PG or 1,3 PD e-liquids was investigated by measuring AC, AP and DA emissions as a function of temperature in an e-cigarette. Thermal generation of AC, AP and DA from sugars was examined by aerosolising e-liquids containing sucrose, fructose or glucose in an e-cigarette. Pyrolytic formation of AP and DA from a range of common flavors was assessed using flash pyrolysis techniques. Results: AC transfer efficiency was >90%, while AP and DA were transferred less efficiently (65%) indicating losses during aerosolisation. Quantifiable levels of DA were generated from VG and PG, and to a lesser extent 1,3 PD at coil temperatures >300°C. Above 350°C AP was generated from VG and 1,3 PD but not PG. AC was not generated from major constituents, although low levels were generated by thermal reduction of DA. Aerosols from e-liquids containing sucrose contained quantifiable (>6 ng/puff) levels of DA at all sucrose concentrations tested, with DA emissions increasing with increasing device power and concentration. 1% glucose, fructose or sucrose e-liquids gave comparable DA emissions. Furanose ring compounds also generate DA and AP when heated to 250°C. Conclusions: In addition to less than quantitative direct transfer from the e-liquid, DA and AP can be present in the e-cigarette aerosol due to thermal decomposition reactions of glycols, sugars and furanonse ring flavors under e-cigarette operating conditions.Keywords
This publication has 27 references indexed in Scilit:
- Emissions from Electronic Cigarettes: Key Parameters Affecting the Release of Harmful ChemicalsEnvironmental Science & Technology, 2016
- Effects of design parameters and puff topography on heating coil temperature and mainstream aerosols in electronic cigarettesAtmospheric Environment, 2016
- Flavoring Chemicals in E-Cigarettes: Diacetyl, 2,3-Pentanedione, and Acetoin in a Sample of 51 Products, Including Fruit-, Candy-, and Cocktail-Flavored E-CigarettesEnvironmental Health Perspectives, 2016
- Correlation of volatile carbonyl yields emitted by e-cigarettes with the temperature of the heating coil and the perceived sensorial quality of the generated vapoursInternational Journal of Hygiene and Environmental Health, 2016
- Diacetyl in Foods: A Review of Safety and Sensory CharacteristicsComprehensive Reviews in Food Science and Food Safety, 2015
- Evaluation of Electronic Cigarette Liquids and Aerosol for the Presence of Selected Inhalation ToxinsNicotine & Tobacco Research, 2014
- Reaction mechanism for glycerol dehydration in the gas phase over a solid acid catalyst determined with on-line gas chromatographyChemical Engineering Science, 2014
- An evaluation of sucrose as a possible contaminant in e-liquids for electronic cigarettes by hydrophilic interaction liquid chromatography–tandem mass spectrometryAnalytical and Bioanalytical Chemistry, 2014
- Does e-cigarette consumption cause passive vaping?Indoor Air, 2012
- New efficient and long-life catalyst for gas-phase glycerol dehydration to acroleinJournal of Catalysis, 2011