Chemical characterisation of e-device aerosols
Electronic devices such as e-cigarettes deliver nicotine without the combustion of tobacco and are increasingly used by global consumers. Typically, the liquid formulation of an e-cigarette is composed of nicotine, excipients (propylene glycol and/or glycerol), water and flavours, and is vaporised and inhaled by the user. Analytical methods used to measure constituents of tobacco smoke can be adapted for the testing of aerosols produced by e-cigarettes, but this may not always be appropriate and may impact the quality of the data. This is because there are large differences in the chemical composition and complexity of mainstream smoke and an e-cigarette aerosol.
The product test parameters such as puff volume, puff profile, frequency and duration of each puff, should be defined to better reflect consumer use. This will result in the development of more representative sampling regimes, the establishment of robust standardised procedures (including the test environment and materials used) for the collection of the aerosol and the optimisation of analytical techniques to provide adequate selectivity of chemical identification and sensitivity of measurement.
Initial investigations indicate a need to approach e-cigarette sample collection very differently when contrasted with traditional combustible techniques. We will present our experiences and demonstrate the need to segregate combustible and non-combustible sampling to limit the risk of cross-contamination with combustible vapour phase compounds such as isoprene and toluene, and flavour components such as menthol. We will provide an overview of our current GC-MS based techniques used to chemically evaluate e-cigarette aerosols and highlight their limitations. Existing vapour phase techniques suffer from low sensitivity as a result of limited sample volume introduction direct from a Tedlar bag. On-going work continues to explore alternative instrumentation in the form of Thermal Desorption GC-TOFMS and GC-HRTOFMS.