Concepts and Preliminary Observations on the Triple-Dimensional Analysis of Complex Volatile Samples by Using GC×GC−TOFMS

Abstract

The high-resolution two-dimensional comprehensive gas chromatography (GC×GC) separation of a complex sample of an essential oil is reported, with tentative identification of selected separated components provided by time-offlight mass spectrometry (TOFMS). The GC×GC technique allows orthogonal separation mechanisms on the two columns to achieve separation of components that otherwise are unresolved on a single column, as is demonstrated for the pairs of components borneol and terpinen-4-ol, and cis-caryophyllene and β-farnesene. Peak compression and a short second column used in GC×GC lead to generation of fast second-dimension GC peaks and higher detection sensitivity, by about 25 times, as compared to conventional GC elution. This allows many more compounds to be recognized when using the GC×GC 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 technique. Application of the technique to the complex essential oil sample containing a range of chemical compound classes shows that superior separation and more accurate peak assignment results. Once peaks are identified within the two-dimensional separation space, it is conceivable that mass spectrometry might no longer be required for the routine analysis of such samples, instead relying on the precision of flame ionization detection to give quantitative analysis; however, the support of mass spectral characterization will be invaluable in validating the GC×GC approach.

Molecular Interactions between the Specialist Herbivore Manduca sexta (Lepidoptera, Sphigidae) and Its Natural Host Nicotiana attenuata. VIII. An Unbiased GCxGC-ToFMS Analysis of the Plant's Elicited Volatile Emissions

“…GCxGC-ToFMS technology has been shown to provide high-quality mass spectra with great sensitivity, largely as a result of the enhanced resolution and zone compression obtained from the orthogonal separation (Shellie et al, 2001). These qualities were exemplified by the 5-to 10-fold increase in the signal-to-noise ratio of a series of commonly emitted volatiles that we compared with the results from one-dimensional analyses performed with the same instrument (data not shown).…”

Allergic asthma exhaled breath metabolome: A challenge for comprehensive two-dimensional gas chromatography

“…Sensitivity and limits of detection are improved due to focusing of the peak in the modulator and separation of analytes from chemical background [8] compared to 1D-GC. ToFMS (time-of-flight mass spectrometry) brings several advantages such as full mass spectra acquisition at trace level sensitivity and mass spectral continuity, which allows for deconvolution of spectra of co-eluted peaks [9]. To the best of our knowledge, GC × GC-ToFMS methodology has never been reported before to study allergic asthma exhaled breath volatile composition.…”

Gas Chromatographic Analysis of Plant and Insect Surface Compounds: Cuticular Waxes and Terpenoids

“…The principles, practical and theoretical aspects, and the most significant developments of GC×GC were reviewed by Mondello et al (2008). There are several reports of GCxGC used for determining essential oils (Dimandja et al, 2000;Shellie et al, 2003;Shellie et al, 2001). …”

“…The high resolution GC×GC separation of an essential oil and the identification of selected separated components by time-of-flight mass spectrometry (TOF-MS) was reported by Shellie et al, (2001). These authors showed that GC×GC allows orthogonal separation mechanisms on the two columns to achieve separation of components (e.g.…”