Lecture
Improved compound identification for target, suspect- and non-target analysis using a GC-EI&CI-TOF-MS system
- 09.04.2024 at 10:00 - 10:30
- ICM Saal 5
- Language: English
- Type: Lecture
Lecture description
Exogenous exposures to environmental contaminants can pose risks to ecosystems and human health. Given the dynamic nature of environments such as water and air, regular target, and non-target analyses (NTA) to monitor and identify these compounds is frequently conducted. Due to its complimentary polarity range, gas chromatography mass spectrometry (GC-MS) is often employed alongside liquid chromatography (LC) electron spray ionization (ESI) high resolution mass spectrometry (HRMS) to evaluate potential hazard profiles and to identify compounds in these complex mixtures to gain a more complete overview of the potential hazards present. However, state-of-the-art GC electron ionization (EI) MS is limited in its identification confidence for some compounds due to unspecific fragmentation pattern, absent molecular ion signals or by not being available in reference libraries, leading to a lack of compound identification [1].
The ecTOF (TOFWERK, Thun, CH) is a newly developed dual ionization source time-of-flight (TOF) mass spectrometer. The instrument consists of a standard TOF analyzer operating two ionization sources simultaneously: a standard 70 eV EI source and a medium pressure chemical ionization (CI) source (HRP; TOFWERK, Thun, CH) [1,2]. By using a fully integrated reagent gas supply unit [2], CI reagents can automatically be switched between GC runs without hardware changes. The ecTOF is coupled to a GC (7890A, Agilent, Santa Clara, USA) using a Y-flow-splitter and custom designed heated transfer lines connect to the two different ionization sources. Depending on the sample, liquid, gas phase or thermo-desorption is chosen as sample introduction method. For preconcentration, different sample preparation methods (e.g. SPME, tenax tubes) can be employed.
This talk will highlight the advantages of using quasi-simultaneously generated EI and CI mass spectra for contaminant identification in complex environmental samples. To show the versatility of the obtained dataset and its potential in compound identification, various samples were analyzed, including industrial wastewater and emissions from car interior parts. The tentative identification processes and statistical approaches that can be employed using the ecTOF data will be shown. Reduced false positive rates using both EI and CI mass spectra as well as the increased identification yields compared to standard GC-MS methods will be presented. The advantage of a chemical ionization setup with high reactant ion flexibility used for various compound classes is shown. The simple selection of different CI reagents ions (e.g., [NH4]+, [N2H]+, [H3O]+) between chromatographic runs, which enables the adjustment of reactant selectivity and the degree of fragmentation, is proven to be highly valuable for the compound identification process. Various methods of using the generated EI- and CI- mass spectral information within library searches and other tools will be presented.
Literature:
[1] Bräkling, S. Anal. Chem. 2022., 94 (15): 6057-6064.
[2] Bräkling, S. et al. J. Rapid Commun. Mass Spectrom., 2023. 37:e9461, 3, 499–509.
The ecTOF (TOFWERK, Thun, CH) is a newly developed dual ionization source time-of-flight (TOF) mass spectrometer. The instrument consists of a standard TOF analyzer operating two ionization sources simultaneously: a standard 70 eV EI source and a medium pressure chemical ionization (CI) source (HRP; TOFWERK, Thun, CH) [1,2]. By using a fully integrated reagent gas supply unit [2], CI reagents can automatically be switched between GC runs without hardware changes. The ecTOF is coupled to a GC (7890A, Agilent, Santa Clara, USA) using a Y-flow-splitter and custom designed heated transfer lines connect to the two different ionization sources. Depending on the sample, liquid, gas phase or thermo-desorption is chosen as sample introduction method. For preconcentration, different sample preparation methods (e.g. SPME, tenax tubes) can be employed.
This talk will highlight the advantages of using quasi-simultaneously generated EI and CI mass spectra for contaminant identification in complex environmental samples. To show the versatility of the obtained dataset and its potential in compound identification, various samples were analyzed, including industrial wastewater and emissions from car interior parts. The tentative identification processes and statistical approaches that can be employed using the ecTOF data will be shown. Reduced false positive rates using both EI and CI mass spectra as well as the increased identification yields compared to standard GC-MS methods will be presented. The advantage of a chemical ionization setup with high reactant ion flexibility used for various compound classes is shown. The simple selection of different CI reagents ions (e.g., [NH4]+, [N2H]+, [H3O]+) between chromatographic runs, which enables the adjustment of reactant selectivity and the degree of fragmentation, is proven to be highly valuable for the compound identification process. Various methods of using the generated EI- and CI- mass spectral information within library searches and other tools will be presented.
Literature:
[1] Bräkling, S. Anal. Chem. 2022., 94 (15): 6057-6064.
[2] Bräkling, S. et al. J. Rapid Commun. Mass Spectrom., 2023. 37:e9461, 3, 499–509.
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