Chemical characterization and quantification of nicotine in e-liquids consumed in Brazil using DI-SPME-GC-MS

Electronic cigarettes and their refill liquids (e-liquids) have become increasingly popular, despite regulatory restrictions in Brazil. The lack of quality control raises concerns regarding the presence of harmful or undeclared substances. This study aimed to perform both target and untargeted analyses of marketed e-liquids in Brazil. A total of 20 samples were analyzed using direct immersion solid-phase microextraction coupled with gas chromatography-mass spectrometry (DI-SPME-GC-MS). The target analysis focused on nicotine quantification in SIM mode, while the untargeted analysis characterized volatile and semi-volatile organic compounds in full-scan mode. The untargeted screening identified approximately 673 compounds, including alcohols, esters, aldehydes, ketones, terpenes, and aromatic hydrocarbons. Toxic compounds such as benzaldehyde, ethyl maltol, benzophenone, myrcene, and 2,3-pentanedione were detected. Emerging contaminants including polycyclic aromatic hydrocarbons (PAHs), phthalates, and benzene derivatives compounds were also found in several samples, indicating contamination and potential health risks. The DI-SPME-GC-MS method was optimized through experimental design and validated, showing good linearity (R² = 0.9986), recovery (86-101 %), precision (RSD <3 %), and adequate quantification limit (LOQ = 0.053 mg L^-1). Nicotine concentrations ranged from 0.005 to 50.672 mg mL^-1 (5.11-50672.10 mg L^-1), with most samples showing discrepancies between labeled and measured values. Even samples labeled as "nicotine-free" contained detectable levels. These findings reveal significant inconsistencies in product labeling and the presence of hazardous compounds, highlighting the urgent need for regulatory oversight and toxicological evaluation of e-liquids consumed in Brazil.