Evaluation of chemical constituents of E-cigarette liquid refills marketed through online in India using NMR analysis

Background Electronic cigarette (e-cigarette) is an emerging class of electronic nicotine-delivery system claimed by the industries as a quitting aid. Laboratory testing of some refill liquids for e-cigarettes(e-liquids) contain impurities and toxic substances, or are not filled true to label. The additional impurities in the liquids or vapour (e.g., polyaromatic hydrocarbons (PAHs), Tobacco specific nitrosamines (TSNAs), aldehydes and acrolein), unexpected toxins and/or unreliable nicotine in different glycols mixed with concentrated flavours, warrants a thorough evaluation of the chemical constituents of these E-liquids. Previous research in the evaluation of these constituents involved gas or liquid chromatography (GC, LC) combined with mass spectrometric (MS) detection for the analysis in combination with 1 H- Nuclear Magnetic Resonance (NMR) analysis. This study aimed to evaluate the chemical composition of e-liquid refills using 1 H- NMR, 13 C-NMR along with DEFT, GCMS and IR spectroscopic analysis. Methods A total of 6 samples marketed and sold highly in India through online, claimed to have 0,3,6,12 and 18 milligrams of nicotine and one sample claiming no nicotine/no tar were identified and purchased. The presence of Tobacco Specific Nitrosamines (TSNAs), tobacco alkaloids, Polycyclic Aromatic Hydrocarbons (PAHs), Volatile Organic Compound (VOCs) were analysed using 1 H- NMR, 13 C-NMR along with DEPT, Gas Chromatography Mass Spectroscopy (GCMS) and IR spectroscopy. Results Significant levels of VOCs were noted which included glycerin, propylene and ethylene glycol. Acrolein and PAH were not detected in the samples. However, presence of additional organic compounds including nitrosamines, and nicotine were detected by 13 C- NMR, DEPT and IR spectroscopy. Conclusions NMR spectroscopy is a useful and rapid method to simultaneously detect several ingredients in e-liquids, and GCMS, IR and DEFT also provided additional information on the constituents of e-liquid products. Systematic evaluation of chemical constituents of the e-cigarette may hence throw light on its possible short term and long term health effects