Transfer of metals in the liquids of electronic cigarettes

Efthimios Zervas, Niki Matsouki, Grigorios Kyriakopoulos, Stavros Poulopoulos, Theophilos Ioannides, Paraskevi Katsaounou

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Objectives: E-cigarettes are electronic devices containing a liquid that usually consists of a mixture of glycerol, propylene glycol and nicotine, with or without flavorings, in various concentrations. A vapor or aerosol is produced, and inhaled from the user, when this liquid is heated by a heating coil. This work examines the impact of three parameters (e-liquid composition, nicotine content and air flow) on the transfer of metals’ from the heating coils to the e-liquids. Materials and methods: A distillation unit was used, where 20ml of an e-liquid were boiled with two commercial heating elements. Four e-liquids: 100% Propylene Glycol, 100% Glycerol, 50/50% Propylene Glycol/Glycerol, 33.3/33.3/33.3% Propylene Glycol/Glycerol/Water, three nicotine contents: 0, 0.4 and 0.8% per volume and three air flows: 0, 0.5 and 1.0 L/min, were used. The liquids were analyzed by Total Reflection X-Ray Fluorescence spectrometry to determine the final content of metals. Results and discussion: Five metals, Fe, Ni, Cu, Zn, and Pb, were found to be transferred from the heating coils to the e-liquids. The transfer of those metals increases with air flow and nicotine concentration, while e-liquid composition also has a significant impact. Glycerol enhances the transfer of metals compared to propylene glycol and their mixtures. The boiling temperature of the e-liquids increases significantly the transfer of metals in the e-liquids. Conclusions: There is a transfer of metals from the heating coils to the e-liquids. This transfer depends on the e-liquid composition and on the boiling temperature.

Original languageEnglish
Pages (from-to)240-248
Number of pages9
JournalInhalation Toxicology
Issue number6
Publication statusPublished - 2020


  • Copper
  • Electronic cigarettes
  • Glycerol
  • Lead
  • Metals
  • Nickel
  • Propylene glycol
  • Zinc

ASJC Scopus subject areas

  • Toxicology
  • Health, Toxicology and Mutagenesis

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