Fingerprints of tobacco smoke precursors by comprehensive GCxGC
In order to mimic the aromatic modifications occurring in tobaccos during combustion, a preparation method, applied on tobacco samples, is carried out. Tobacco samples are heated under pressure at 170 °C during 2 hours. In such conditions, Maillard reactions are initiated, responsible from part of the aroma of the smoke. Due to the complexity of the extracts, the chromatograms obtained by GC-FID or GC-NPD show a lot of co-elutions, the identification of the compounds is troublesome and a rapid comparison of the samples is not possible. Comprehensive two-dimensional gas chromatography, GC×GC, has proved to be clearly advantageous for improving the selectivity of the separations and also for giving organised chromatograms on the 2D space plane. We have implemented this technique for the analysis of the heated tobacco extracts. The conditions of separation of the main families of Maillard compounds or of other smoke precursors were optimized: the pyrazine, pyridine and carbonyl derivatives are clearly separated on the second dimension column. With this technique, an at-a-glance investigation of the main differences between tobacco types was possible, allowing to compare the tobaccos on an aromatic point of view. New discriminating compounds could be identified. To take also into account the risk-associated part of the smoke, the compounds that characterized the best the different tobaccos have been selected by multidimensional analysis and have been compared to smoke compounds generated by cigarettes based on the same tobaccos. This way, a tobacco fingerprint, which could be linked to its aromatic or toxic potential in smoke, has been defined. Finally, with this method, the interactions between tobacco types during heating have been investigated as well as the effects of different additives.