Aim and objective:
In the last years, the use of e-cigarettes has significantly increased in some countries as an alternative to conventional cigarettes. Despite its success in the markets, to date, there is limited research on its safety and impact on human health. The objective of this work, beyond the quantification of nicotine, was the development and validation of an analytical procedure to quantify 1,2-Propyleneglycol, 1,3 -Propyleneglycol and and Glycerol, the main humectant components of e-cigarette liquids as potential biomarkers of exposure to e-cigarette emissions.

Methods:
A volume of 0.1 mL of sample was derivatized with benzoyl chloride in alkaline medium, followed by a rapid simple extraction with hexane. The instrumental analysis was performed using gas chromatography coupled to mass spectrometry, with electron impact ionization and selected ion monitoring. The method was validated following European Medicines Agency guidelines.

Results:
The method was validated in a concentration range of 3-700 μmol/L, showing good selectivity, linearity, precision and accuracy. It works properly for the quantification of the e-cigarette’s humectants uptake in human body. Concentration levels of all humectant components were significantly higher in samples from users than from nonusers as tested during method validation.

Conclusions:
1,2-Propyleneglycol, and 1,3 -Propyleneglycol analysed in body fluids are good biomarkers to characterize the use of e-cigarette. They may be used for the study of the impact of e-cigarettes use on health.

Funding:
Instituto de Salud Carlos III, Subdirección General de Evaluación y Fomento de la Investigación, PN I+D+I 2008–2011, co-funded by the European Regional Development Fund (FEDER), Government of Spain (grants PI15/00434 and PI15/00291).