Portland State University. Department of Chemistry
David H. Peyton
Date of Publication
Doctor of Philosophy (Ph.D.) in Chemistry
Electronic cigarettes -- Research, Nicotine -- Research
1 online resource (xvi, 181 pages)
Electronic cigarettes (e-cigarettes) are an increasingly popular tobacco product used by ~3% of adults and 21% of 12th grade students (as reported for the prior 30-days in surveys) in the United States in 2018. As of 2019, this number went up to ~25% for 12th grade students. Due to how quickly e-cigarettes gained popularity and the rapid design changes that have ensued, there has not been enough time to accurately assess the effects of e-cigarettes, particularly for long-term use. The liquids used in e-cigarettes (e-liquids) can degrade when vaped in an e-cigarette, so understanding the variables that can modulate degradation is useful for harm-reduction strategies. It is also useful to analyze various aspects of nicotine in e-liquids as this could influence the addictiveness of a product.
This dissertation contains four manuscripts that broadly cover two categories of questions. 1) In order to evaluate the variables that can contribute to degradation in e-cigarettes, a) the boiling points (i.e. aerosolization temperatures) of propylene glycol (PG) + glycerol (GL) mixtures were determined (+ additives) and b) the effect of sucralose on aldehyde and hemiacetal formation via solvent degradation was explored. 2) Nicotine in e-liquids was analyzed in terms of a) protonation state (i.e. free-base vs monoprotonated), b) acid/nicotine ratio, and c) concentration, because these variables can alter the impact and addictiveness of a product. Primary findings in the four manuscripts include: 1) the boiling points of PG + GL mixtures were determined and ranged from 188.6 °C (PG) to 292 °C (GL). Parameterizations were determined using the Gibbs-Konovalov theorem so that the boiling point of a PG/GL mixture can be calculated for any PG/GL ratio. Mixture boiling points were also evaluated with additives (2.5 mol% water, 5 mol% water, and 3 mol% nicotine). Added water decreased the boiling points of all mixtures tested, and added nicotine decreased the boiling points of some PG/GL mixtures. 2) The addition of sucralose to e-liquids resulted in more aldehyde and hemiformal production via degradation when vaporized in an e-cigarette compared to identical sucralose-free e-liquids vaped under identical conditions. Sucralose was determined to be unstable to the vaping conditions in the e-cigarettes tested, and its degradation products then enhanced degradation of the solvents PG and GL. In manuscripts 3) and 4), the ratio of free-base nicotine relative to monoprotonated nicotine (αfb) was determined for a number of commercially available e-liquids including bottles ("salt" nicotine and "non-salt" nicotine), JUUL pods, and other JUUL-alikes/pods. Traditional e-liquids/pods and "salt" nicotine e-liquids/pods were evaluated for αfb, acid/nicotine ratio, and nicotine concentration. αfb ranged from 0.00 to 0.98 for all commercial e-liquids tested, acid/nicotine ratio ranged from 0 to 4.03 by mol, and nicotine concentrations ranged from 3 to 62 mg/mL for tested e-liquids. Over time, e-liquid manufacture has shifted from low nicotine concentration/high αfb content to higher nicotine concentration/lower αfb content (i.e. "salt" nicotine, such as JUUL and others), which results in a product that remains easily inhalable due to the reduced harshness, despite the relatively high nicotine content.
In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
Duell, Anna Katherine, "Analysis of E-cigarette Liquids and Aerosols by NMR Spectroscopy: Compositions, Boiling Points, and Degradation Profiles" (2019). Dissertations and Theses. Paper 5351.