GC/TOF MS Application: Analysis of urban or industrial air by TD-GC/TOF-MS
 Air monitoring of trace-level ‘hazardous air pollutants’ in urban and industrial environments is enforced by various regulations; the international standard methods TO-15 and TO-17 provide a list of trace-level air toxics which must be looked for in an air sample.
The complexity of air, giving rise to interference and co-elution, means that component identification can be difficult and time-consuming. Historically, SIM analysis was used to give the required sensitivity but this precludes the gathering of full spectral data. Thermal desorption of the air sample to GC, followed by an advanced TOF-MS allows SIM-like sensitivity with full spectral data for conclusive identification of trace level toxics.
Analytical system
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Thermal desorber
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GC
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TOF-MS
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- Instrument: UNITY 2–Air Server™
- TD flow path: 140°C
- Trap: Air Toxics Analyser (C2 to C30) U-T15ATA-2S
- Trap low temp: 25°C
- Trap purge time: 2.0 min
- Trap heating rate: 40°C/min
- Trap high temp: 320°C
- Split: 10:1
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- Column: 60 m x 0.32 x 1.8 µm
- Temperature programme: 35°C (5 min), 5°C/min to 230°C
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- Instrument: BenchTOF-dx™
- Transfer line: 200°C
- Mass range: 35–300 Da
- Data acquisition rate: 5000 spectra per data point
- Ion source: 200°C
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Results
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Unlike all other TOF MS systems, BenchTOF-dx produces classical EI spectra (10,000 spectra/sec). The total ion chromatogram (TIC) of an urban air sample highlights multiple TO-15/TO-17 compounds.
Components are represented by their classical EI spectra, which allow components to be searched in an established library. A trace-level compound, Freon® 113, has been identified by searching the classical spectrum of a small peak eluting at 6.97 min.
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Conclusion
The BenchTOF-dx provides high sensitivity analysis. This, together with the generation of classical EI spectra, allows for the identification of a large range of compounds, e.g. those of the TO-15/TO-17 list, in a single analysis.
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