LP-02 Urinary Biomarker Trends of Oxygenated and Nitrated PAHs in Smokers Transitioning to Exclusive Electronic Cigarette Use

Tobacco smoke is a complex mixture of gaseous and particulate-bound compounds containing thousands of chemicals, many of which are known human carcinogens. 1 , 2 In recent years, electronic cigarettes (ECs) have gained significant popularity, especially among younger populations, as an alternative to traditional tobacco smoking. EC manufacturers claim that heating e-liquids produces fewer harmful respiratory effects compared to the combustion of tobacco. This study analysed 100 urine samples from 20 participants (aged 20–68) who switched to exclusive EC use for 28 days to assess changes in PAH biomarkers, including their oxygenated and nitrated derivatives. We utilised automated solid-phase microextraction (SPME) in both headspace (HS) and direct immersion (DI) modes to compare the extraction efficiencies of target analytes using a PDMS/DVB SPME fibre, followed by quantification via GC-MS/MS. In addition, we evaluated the performance of the SPME method against conventional liquid injection, where urine samples were purified using solid-phase extraction (SPE) cartridges and eluted with 1 mL of acetonitrile prior to GC-MS analysis. Direct immersion of the SPME fibre into diluted urine samples, incubated at 70°C for 30 minutes, yielded the highest extraction efficiency and analytical sensitivity. Results showed that in 80% of the samples analysed, PAH biomarkers and their derivatives decreased by up to 90% after switching to ECs. The study highlights opportunities to further improve analytical sensitivity using longer SPME fibres (2 cm vs. 1 cm) or softer ionisation techniques such as chemical ionisation (CI). These findings support the potential for reduced exposure to certain toxicants with EC use, while underscoring the need for continued refinement of analytical approaches for sensitive detection of low-abundance PAH derivatives.