High-Speed GC and GC/Time-of-Flight MS of Lemon and Lime Oil Samples

Abstract

The high-speed GC separation and MS characterization of lime oil and lemon oil samples using programmable column selectivity and time-of-flight mass spectrometry is described. The volatile essential oils are separated on a series-coupled (tandem) column ensemble consisting of a polar trifluoropropylmethyl polysiloxane column and a nonpolar 5% phenyl dimethyl polysiloxane column. Both columns are 7 m long. A 50 degrees C/min linear temperature ramp from 50 to 200 degrees C is used, giving an analysis time of approximately 2.5 min. A time-of-flight MS with time array detection and automated peak finding and characterization software was used to identify 50 components in lime oil samples and 25 components in lemon oil samples. Despite numerous cases of extensive peak overlap, spectral deconvolution software was very successful in the characterization of most overlapping peaks. For cases where a more complete chromatographic separation is desirable, the tandem column ensemble is operated in the first-column stop-flow mode to enhance the separation of selected overlapping clusters of peaks. A valve between the junction point of the tandem column ensemble and a source of carrier gas at the GC inlet pressure is opened for 2-5-s intervals to stop the flow of carrier gas in the first column. This is used to increase the separation of target component groups that overlap in the ensemble chromatogram without first-column stop-flow operation. This procedure is used to isolate the peak for limonene, the largest peak in the analytical-ion chromatogram of both the lime and lemon oil samples.

Correlative GC-TOF-MS-based metabolite profiling and LC-MS-based protein profiling reveal time-related systemic regulation of metabolite–protein networks and improve pattern recognition for multiple biomarker selection

“…Recently, we introduced GC-TOF-MS analysis of ultra-complex plant extracts for the detection and quantification of several hundreds of metabolites in a single sample (Weckwerth et al, 2001. This method provides a hitherto unknown magnitude of metabolite detection due to a unique combination of high resolution gas chromatography with a rapid and sensitive time-of-flight mass analyzer (Watson et al, 1990;Leonard and Sacks, 1999;Veriotti and Sacks, 2001). It further accelerates the analyses thereby increasing sample throughput.…”

Rapid analysis of food products by means of high speed gas chromatography

“…The latter reports essential information relative to each application, which will not be repeated in this section (more details may be derived by directly consulting the reference). In the field of narrow-bore column fast GC research, a total of 18 essential oil applications are reported [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]; Table 1 also reports the use of a short conventional column in fast GC essential oil analysis [9], while eight are focussed on fatty acid methyl ester (FAME) analysis [44][45][46][47][48][49][50][51]; single works regard triglycerides [52] and an alcoholic beverage [53]. More detailed information will be provided hereafter for some of the most representative high-speed GC examples.…”

An Overview of Analytical Applications of Time of Flight-Mass Spectrometric (TOF-MS) Analyzers and an Inductively Coupled Plasma-TOF-MS Technique

“…102 The identification of 50 components in lime oil samples and 25 components in lemon oil samples by using GC-TOF-MS has been described. 103 The analysis of proteins is an example of the use of on-line capillary HPLC, electrochromatography and capillary electrophoresis coupled with ion-trap reflectron TOF-MS. 104,105 TOF-MS has recently been effectively combined with HPLC for the determination of pesticides in environmental water samples. 106 The use of ESI-TOF-MS detectors for HPLC and CE is mentioned above.…”