E-Liquid and Aerosol Composition of Four Popular Disposable E-cigarettes

Oct 13, 2026

Disposable electronic cigarettes are among the most popular nicotine delivery products for adults and adolescents, yet their organic composition and vaping chemistry remain insufficiently characterized. This thesis analyzes the organic composition of e-liquids and aerosols from four disposable brands, measuring nicotine concentration and chirality, organic acids, and flavor plus coolant content. It also evaluates aerosol mass and carbonyl species formed during vaping using GC-MS and LC-MS with accurate mass. Results show large nicotine-label discrepancies, consistent absence of (R)-(+)-nicotine, and high levels of WS-23, with notable carbonyl variability.

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UC Davis UC Davis Electronic Theses and Dissertations Title E-Liquid and Aerosol Composition of Four Popular Disposable E-cigarettes Permalink [https://escholarship.org/uc/item/3tf7013w](https://escholarship.org/uc/item/3tf7013w) Author Robertson, Nicholas Eric Publication Date 2025 Peer reviewed|Thesis/dissertation [eScholarship.org](eScholarship.org) Powered by the California Digital Library University of California E-Liquid and Aerosol Composition of Four Popular Disposable E-cigarettes By NICHOLAS ROBERTSON THESIS Submitted in partial satisfaction of the requirements for the degree of MASTER OF SCIENCE in Agricultural and Environmental Chemistry in the OFFICE OF GRADUATE STUDIES of the UNIVERSITY OF CALIFORNIA DAVIS Approved: | Tran Nguyen, Chair | | --- | | Brett Poulin | Sascha Nicklisch Committee in Charge 2025 Acknowledgements I would like to express my deepest gratitude to my family, whose unwavering encouragement has been my foundation throughout this journey. Their belief in me has been a constant source of strength and allowed me to reach this point in my life. To my friends, thank you for your support, patience, and for always reminding me to take a break when needed. Your companionship made this experience even more enjoyable. I am also immensely grateful to my fellow lab members, collaborators, and mentors whose collaboration, insightful discussions, and shared moments of frustration and success have made this academic journey truly memorable. Your guidance and camaraderie have played an invaluable role in my growth as a researcher. Thank you all for being part of this chapter of my life. Abstract Disposable electronic cigarettes (e-cigarettes) are one of the most popular forms of nicotine consumption among both adults and adolescents. The organic composition of these devices and the chemistry that occurs during the vaping process remain poorly understood. This work investigates the organic composition of e-liquids and aerosols from four popular disposable brands: Flum Pebble, Elf Bar, Esco Bars, and Geek Bar. We investigated the nicotine concentration, enantiomeric identity of nicotine, concentration and identity of organic acids, and flavor and coolant content of the e-liquids. Additionally, we investigated the formation of aerosol mass and carbonyl species formed during vaping. Analyses were performed using a combination of gas chromatography coupled to mass spectrometry, and liquid chromatography coupled to accurate-mass mass spectrometry. We found significant variations in nicotine concentration, with 16 of the 25 devices differing by more than 20% from their labeled values. No products in this study contained the non-natural (R)-(+)-nicotine enantiomer. These products primarily used benzoic acid as the organic acid to form nicotine salts. Seven products contained notable concentrations of levulinic acid in addition to benzoic acid. The concentration of organic acids varied greatly, leading to benzoic acid to nicotine molar ratios between 0.35 and 3.91. These ratios varied greatly both between and within brands, with no clear correlation to brand or flavor profile. All examined products contained high concentrations ofthe synthetic coolant WS-23, comprising 1.2-6.77% of the e-liquid. The flavor chemicals vanillin, ethyl maltol, triacetin, and (3Z)-3-hexen- 1-ol were found in most devices and individually exceeded 1% of the e-liquid in three devices. Esco Bars produced the highest yield of carbonyls in the aerosol, while Flum Pebbles produced the lowest. There was significant variability between and within brands. These devices contain several components that pose health concerns, present in the e-liquid and produced in the aerosol. 1. Introduction Electronic (e-) cigarettes are the most commonly used tobacco products among U. S youth.1-3 In the United States, 20% of high school students have used an e-cigarette at least once,4 and 10%

FAQs

Which disposable e-cigarette brands were investigated in the thesis?

The study analyzed e-liquids and aerosols from four popular disposable brands: Flum Pebble, Elf Bar, Esco Bars, and Geek Bar.

What methods were used to analyze nicotine, organics, and aerosol products?

Analyses used gas chromatography coupled to mass spectrometry (GC-MS) and liquid chromatography coupled to accurate-mass mass spectrometry (LC-MS).

What major findings were reported about nicotine and organic acids?

Nicotine concentrations varied substantially from labeled values, none contained the non-natural (R)-(+)-nicotine enantiomer, and nicotine salts were primarily formed with benzoic acid. Organic-acid levels varied widely, producing benzoic-acid-to-nicotine molar ratios from 0.35 to 3.91.

Oct 13, 2026

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