Abstract
<jats:p>The growing use of nicotine-containing electronic cigarette liquids (e-liquids) raises significant public health concerns relating to health promotion, regulatory oversight, and disease prevention. Nicotine in e-liquids is produced either by chemical synthesis or extracted naturally from tobacco plants. Although synthetic nicotine currently escaped specific tobacco taxation in some countries, regulatory changes in many governments are shifting to classify synthetic nicotine products under similar excise and oversight frameworks as tobacco-derived nicotine. Nicotine exists as two isomers: R- and S- nicotine. Naturally derived nicotine consists predominantly of the S-isomer (≥ 99%), whereas synthetic nicotine typically contains a mixture of R- and S-isomers in equal proportions. In this study, 11 types of commercially available e-liquids were analyzed to determine the origin of their nicotine, natural or synthetic using gas chromatography–mass spectrometry (GC-MS). Additionally, 53 volatile compounds including alcohols, esters, terpenes, aromatic compounds, and lactones were identified, providing comprehensive product profiles. All samples contained near equal proportions of R- and S-nicotine, indicative of synthetic origins. This novel integrative chemical analysis approach supports regulatory authorities by providing a robust, reproducible method for authenticating nicotine sources in e-liquids, thereby enhancing global public health regulatory frameworks and promoting consumer protection.</jats:p>