Unique Benefits Delivered by Orbitrap GC Technology for Non-Targeted Analysis

Importance of the Topic

High-resolution gas chromatography–mass spectrometry (GC–MS) has become indispensable in environmental monitoring, food safety, clinical toxicology, and industrial quality control. Advanced Orbitrap GC technology markedly enhances selectivity, sensitivity, and mass accuracy compared with conventional GC–MS, enabling reliable detection and confident identification of trace-level compounds and unknowns in complex matrices.

Objectives and Overview

This study introduces the unique benefits of Thermo Scientific Orbitrap GC/MS platforms for both targeted and non-targeted analyses. Four key applications are addressed:

• Routine targeted screening and confirmation of known analytes.
• Identification of “known unknowns” via high-resolution filtering and spectral libraries.
• Discovery workflows for true unknowns combining chemical ionization (CI), tandem MS (MS/MS), and automated software tools.
• Demonstration of performance metrics—resolution, mass accuracy, dynamic range, and sensitivity—in various real-world scenarios.

Methodology and Instrumentation

Samples included pesticide-spiked produce, chlorinated water, and pharmaceutical impurities. Procedures involved standard GC sample preparation (e.g., QuEChERS), followed by analysis on Orbitrap GC systems under electron ionization (EI) and optional chemical ionization (CI). Key instrumentation components:

• Q Exactive GC Orbitrap GC-MS/MS System (up to 120 000 FWHM resolution, full-scan, timed-SIM, MS/MS capability).
• Exactive GC Orbitrap GC-MS System (60 000 FWHM, EI/CI, full-scan, timed-SIM).
• TRACE 1310 GC System with rapid heat cycling and modular injector/detector.
• ExtractaBrite ion source, C-Trap, bent flatapole, AQT quadrupole for precursor isolation, HCD collision cell.
• Data processing with TraceFinder, Compound Discoverer, Mass Frontier, and mzCloud library searches.

Main Results and Discussion

High resolution (60 000–120 000) provided exceptional selectivity, isolating pesticides such as pyrimethanil in leek at 10 ppb with minimal interferences using narrow extraction windows (<±5 mDa). Mass accuracy consistently remained below 1 ppm across concentration ranges and matrices, supporting confident formula assignments and compound confirmation. Dynamic range exceeded six orders of magnitude and full-scan sensitivity reached low-ppb to sub-ppb levels comparable to triple-quadrupole methods. Untargeted workflows leveraged deconvolution and high-resolution filtering (HRF) to propose and confirm structures of disinfection by-products and unknown contaminants. CI-based adduct detection and MS/MS fragmentation, combined with automated mzCloud and ChemSpider searches, enabled rapid elucidation of molecular formulas and backbone structures without library matches.

Benefits and Practical Applications

• Single-run full-scan quantitation and screening for >100 pesticides with RSD <3% and calibration linearity (R2 >0.999) over 1–200 ppb.
• Reliable identification of disinfection by-products in water, including halogenated species formed under chlorination or chloramination.
• True unknown discovery in pharmaceutical impurity profiling through CI MS/MS, isotope fine-structure, and fragment prediction.
• Streamlined data processing and reporting via TraceFinder and Compound Discoverer to support QA/QC workflows.

Future Trends and Potential Applications

Advances will target integration with ion mobility for orthogonal separation, deeper non-target screening databases, and AI-driven spectral interpretation. Miniaturized and high-throughput configurations are expected for field-deployable environmental monitoring and real-time process analytics in the pharmaceutical and food industries.

Conclusion

Orbitrap GC technology delivers unprecedented depth in GC–MS analysis, combining high resolution, sub-ppm mass accuracy, broad dynamic range, and sensitivity. It bridges targeted quantitation and exploratory profiling, enabling effective screening, confirmation, and discovery of both known and unknown compounds in complex samples.

Reference

Richardson SD. Occurrence, genotoxicity, and carcinogenicity of regulated and emerging disinfection by-products in drinking water: a review and roadmap for research. Mutat Res. 2002; 227–224.