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The GC-Q-TOF consists of a high-resolution accurate mass Q-q-TOF 7200 mass spectrometer coupled to a 7890B gas chromatograph (Agilent). The mass spectrometer can be operated in EI and positive or negative CI modes of ionization. Only helium can be used as a carrier gas for the GC separations using this instrument. The GC-MS system is equipped with a Sampler 80 (Agilent), which has liquid, static headspace, and SPME sampling options. Methane is available for CI studies.
The instrument can be used for targeted and non-targeted quantitative analysis, structure elucidation, and screening analysis of unknowns at high sensitivity. The combination of EI, CI, and MS/MS is very useful for the analysis of unknowns. Negative CI is of particular interest in analyzing high electron affinity compounds (containing electronegative groups like halogens, nitro, etc.).
Available software: MassHunter.
Repairing Q-TOF 7200....
Our lab did not purchase the new GC-QTOF 7200. The old and non-operating instrument was kindly provided to us by another laboratory. In the course of refurbishing, there were replaced all three turbomolecular pumps, deposits of dust and oil were washed from printed circuit boards, and there was assembled one working inner computer from the two damaged ones.
Surprisingly, the QTOF has returned for a new life...
Removable ion source
Flight tube and the ion mirror
Pulser and MCP detector
Damaged turbomolecular pump
Almost done
Schematic view of the major Q-TOF 7200 components
The advantages of the Q-TOF instrument over conventional quadrupole mass spectrometers are much higher sensitivity, resolution, and mass accuracy. The sensitivity of TOF instruments is not far from that of the triple-quad operated in MRM mode but the difference is that the full mass spectrum is measured in TOF while MRM is a targeted analysis. In other words, using the GC-TOF technique unknowns can be detected and identified at sensitivity close to triple-quad operated in the most sensitive mode.
Below there is a demonstration of Q-TOF superiority over a convenient single-quad GC-MS instrument.
The case. A chicken farm got a new batch of wooden chips which were strewed all over the ground and caused the death of many birds. Our laboratory received samples of good and bad wooden chips for analysis. The analysis was started with the single-quad GC-MS, and after nothing was found, continued using the GC-Q-TOF.
There were detected a lot of polycyclic aromatic hydrocarbons, dioxin (though not very toxic), and other chemicals in bad chips using the Q-TOF. Normal wood chips had plenty of terpenes.
The GC-MS chromatogram of wood chips extract recorded on a single quadruple GC-MS (Agilent 5973C).
The GC-HRMS chromatogram of the same as the above sample of wood chips extract recorded using GC-Q-TOF (Agilent 7200).
There were hardly detected less than a dozen compounds by a single-quad GC-MS analysis while over a hundred compounds were detected using the QTOF in the same sample.
The SPME GC-HRMS chromatogram of wood chips recorded using GC-Q-TOF (Agilent 7200).
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