Analytical method of free and conjugated neutral aroma components in tobacco by solvent extraction coupled with comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry

A reliable and simple method for quantitative analysis of free and conjugated neutral aroma components (including aldehydes, ketones, alcohols, esters and alkenes) in tobacco using comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC–TOFMS) is described. Simple solvent extraction using methyl tert-butyl ether (MTBE) ensured extraction of the neutral aroma components in their free form. The components present as conjugates were isolated using MTBE extraction following acid-catalysed hydrolysis. The GC × GC–TOFMS analysis was performed to comprehensively identify different forms of neutral aroma components in tobacco. Compared with the conventional methods, our method not only simplified the process but also saved time and solvent. It also exhibited higher selectivity and sensitivity and demonstrated the following results: the limit of detection of the neutral aroma components varied from 0.006 μg/g for 2-acetylfuran to 0.133 μg/g for 5-(hydroxymethyl)-2-furfural, the relative standard deviations were from 0.5% to 6.8% and the recovery ranged from 82.4% to 118.2%. The optimized method was successfully employed to analyse real tobacco samples. Eighty-three neutral aroma components of interest were identified.