Flow-Modulated Comprehensive Two-Dimensional Gas Chromatography Combined with a High-Resolution Time-of-Flight Mass Spectrometer: A Proof-of-Principle Study

Abstract

The present research is focused on the evaluation of a recently developed high-resolution time-of-flight mass spectrometer (HR TOF MS), under the challenging conditions of a flow-modulation comprehensive two-dimensional gas chromatography (FM GC × GC) experiment. The HR TOF MS instrument was operated at a spectral generation frequency of 30 Hz and a mass resolution of ≥25,000 (fwhm). The effluent exiting the second-dimension column was in the range 6-8 mL/min, with part directed to waste to avoid exceeding the maximum pumping capacity of the MS system. An FM GC × GC-HR TOF MS method was developed for the untargeted and targeted analysis of a sample of high complexity, namely, heavy gas oil. With regard to the untargeted results, these were satisfactory in relation to MS database searching and mass accuracies. Considering the targeted data, the high selectivity of the MS system was highlighted by the use of accurate mass extracted-ion-chromatograms with narrow mass windows (±5 and ±1 ppm), for specific classes of polyaromatic sulfur heterocycles (PASHs), namely, benzothiophenes and dibenzothiophenes. Finally, the instrumental performance was also evaluated through the injection of standard solutions of four classes of PASHs.

Evaluation of gas chromatography – electron ionization – full scan high resolution Orbitrap mass spectrometry for pesticide residue analysis

“…The scan speeds of 3.8-18 scans/s were lower than can be obtained with GC-EI-TOF-MS systems (up to 50 [23] or even 200 scans/s [28]). They are, however, in the same range that are actually applied in residue applications using TOF-MS (5 scans/s) since scan speeds of 10 scans/s and higher were reported to result in loss of signal, sensitivity and spectral fidelity [23].…”

“…However, thus far, hardly any applications have been described in the scientific literature [27,28].…”

Multiplexing in Multi-Reflecting TOF MS

“…The described ion optical scheme of the planar multireflecting TOF mass analyzer with periodic lenses and double-orthogonal acceleration was commercially implemented by LECO Corporation (St. Joseph, MI, USA) in the Citius LC-HRT [113] and Pegasus GC-HRT [114][115][116][117] mass spectrometers.…”

Investigating aroma diversity combining purge‐and‐trap, comprehensive two‐dimensional gas chromatography, and mass spectrometry

“…In recent years, thanks in part to a common intent to make the use of GC × GC less expensive and more accessible, cryogenic‐free or pneumatic modulators have gained attention . Among the latter group, recent studies have demonstrated that the combination of differential flow modulators with MS is effective, maintaining the high sensitivity and selectivity typical of the GC × GC technique . The reader is directed to the literature for detailed explanations on the modulation forms, with their advantages and drawbacks .…”