Portland State University. Department of Chemistry
David H. Peyton
Date of Publication
Doctor of Philosophy (Ph.D.) in Chemistry
Electronic cigarettes, Cigarette smoke -- Composition, Cigarette smoke -- Analysis, Glycols, Formaldehyde, Tobacco
1 online resource (x, 169 pages)
Electronic cigarette liquid (e-liquid) is a solution of propylene glycol and/or glycerol with varying concentrations of nicotine and flavorants. Inhalation of vaporized e-liquid is a method of nicotine delivery that is growing in popularity and is commonly regarded as safe relative to smoking traditional tobacco products. The thermal decomposition of glycerol and propylene glycol is typical of alcohols and has been investigated, although not exhaustively. In this work, samples of propylene glycol and glycerol were vaporized using an electronic cigarette (e-cigarette) and were analyzed for evidence of decomposition using nuclear magnetic resonance (NMR) spectroscopy. E-cigarettes are shown to degrade glycerol and propylene glycol into a diverse array of oxidation and dehydration products including glyceraldehyde, lactaldehyde, dihydroxyacetone, hydroxyacetone, glycidol, acrolein, propanal, acetone, allyl alcohol, acetic acid, acetaldehyde, formic acid, and formaldehyde. Evidence is presented that the abundance of these decomposition products may depend upon the temperature of the metal heating element but could also depend upon some catalytic aspect of the metal surface. The combination of formaldehyde with alcohols such as glycerol and propylene glycol was explored; hemiformals are stable hemiacetals that can be detected by NMR spectroscopy and are shown to be subject to hydrolysis when diluted in water. Investigations into smoking a glycerol-based tobacco mixture known as shisha using charcoals instead of metal heating elements also resulted in the dehydration of glycerol and sugars.
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Jensen, Robert Paul, "Thermal Decomposition of Electronic Cigarette Liquids" (2016). Dissertations and Theses. Paper 3081.