oThe present research is focused on the qualitative elucidation of the chemical profile of fresh tea tree essential oil and an oxidized, aged (circa 1984) counterpart by using the most powerful analytical tool available today for volatile analysis, namely comprehensive two-dimensional gas chromatography (GC×GC) in combination with a mass spectrometer (MS). The rapid-scanning quadrupole (q) MS system employed generated a sufficient number of spectra/s (20/s) for the reliable identification of the high-speed GC×GC peaks. The total ion current GC×GC–qMS chromatogram of the fresh product was characterized by the presence of ~ 130 unknowns. Among these, 61 peaks were assigned with spectral similarities ≥ 90%, while 28 components presented MS library matches in the 80–89% range. With regards to the oxidized essential oil, about 180 volatiles were visible on the 2D plane with 63 of these characterized by library “hits” ≥ 90% and 45 presenting similarities within the 80–89% range. The use of the enhanced-resolution 3D methodology enabled the full separation of the samples analyzed and, hence, a clear distinction between the essential oils.
