Chemical Elements, Flavor Chemicals, and Nicotine in Unused and Used Electronic Cigarettes Aged 5-10 Years and Effects of pH

31 October 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The concentrations of elements/metals, nicotine, flavor chemicals and acids were com-pared in the e-liquids of unused and used first-generation electronic cigarettes (ECs) that were stored for 5-10 years. Metal analysis was done using inductively coupled plasma optical emission spectroscopy; nicotine and flavor chemical analysis were measured using gas chromatography/mass spectroscopy. Of 22 elements analyzed, 10 (aluminum, chromium, copper, iron, lead, nickel, selenium, silicon, tin, zinc) were often in the e-liquids. Five elements had the highest average concentrations: copper (1,161.6 mg/L), zinc (295.8 mg/L), tin (287.6 mg/L), nickel (71.1 mg/L), and lead (50.3 mg/L). Nicotine concentrations were always lower than label concentrations. Of 181 flavor chemicals analyzed, 11 were measured in at least one sample, with hydroxyacetone being present in all samples. In used products, some flavor chemicals appeared to be byproducts of heating. E-liquids with the highest concentrations of acids and lowest pHs also had the highest concentrations of elements/metals. Metal concentrations in e-liquids increased after use in some products, and some metal concentrations, such as nickel, were high enough to be a health concern. Leachates from discarded ECs could contribute toxic metals/chemicals to the environment sup-porting the need for better regulation of atomizer design, composition, and disposal.


electronic cigarettes
flavor chemicals
environmental waste

Supplementary materials

Supplemental Material
Table of Contents Supplemental Table 1: EC selection and materials list. Running conditions for ICP-OES and GC/MS Supplemental Table 2-4. Brand, sample, average element concentrations and total concentrations (mg/L) Supplemental Table 5. Individual element concentration ranges for aged unused and used EC fluid Supplemental Table 6. Brands which had the elements with the highest concentrations. Supplemental Table 7. Element, brand, sample type, highest concentration in alphabetical and decreasing order. Supplemental Figures 1-22. Individual element concentrations in unused, gently used, and heavily used first generation EC fluid. Supplemental Table 8. Correlation between elements in unused (U), gently used (G), and heavily used (H) e-liquid and elements in EC atomizers. Supplemental Table 9. Flavor chemicals and acids in aged unused and used e-liquids that were below LOQ or not detected Supplemental Table 10. Concentrations of elements in fluid (μg/mg) Supplemental Table 11. Element/metal concentrations (mg/L) in cigarette butts (CB) and EC cartomizers


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.