Concepts and preliminary observations on the triple-dimensional analysis of complex volatile samples by using GCxGC-TOFMS

The high-resolution two-dimensional comprehensive gas chromatography (GCxGC ) separation of a complex sample of an essential oil is reported, with tent ative identification of selected separated components provided by time-of-f light mass spectrometry (TOFMS). The GCxGC technique allows orthogonal sepa ration mechanisms on the two columns to achieve separation of components th at otherwise are unresolved on a single column, as is demonstrated for the pairs of components borneol and terpinen-4-ol, and cis-caryophyllene and be ta -farnesene, peak compression and a short second column used in GCxGC lea d to generation of fast second-dimension GC peaks and higher detection sens itivity, by about 25 times, as compared to conventional GC elution. This al lot vs many more compounds to be recognized when using the GCxGC approach. Additionally, rapid mass spectral methods are required if accurate data and reliable searchable spectra are to be obtained for the fast peaks; this is achieved with TOFMS. This leads to a three-dimensional analytical techniqu e. Application of the technique to the complex essential oil sample contain ing a range of chemical compound classes shows that superior separation and more accurate peak assignment results. Once peaks are identified within th e two-dimensional separation space, it is conceivable that mass spectrometr y might no longer be required for the routine analysis of such samples, ins tead relying on the precision of flame ionization detection to give quantit ative analysis; however, the support of mass spectral characterization will be invaluable in validating the GCxGC approach.