In a previous post, Is it True that “GC-MS is About to Change Forever? (link to post) I described the anticipation and intrigue shown and questions asked by analysts when the news of this new gas chromatography system (Thermo Scientific Q Exactive GC Orbitrap GC-MS/MS system) incorporating Orbitrap technology was first leaked at the 128th annual AOAC meeting.
Advantages of Mass Accuracy
At the Pesticides Symposium, both Dr. Hans Mol (RIKILT Research Institute) and Professor Jana Hajslova (ICT, Prague) presented new data obtained using the GC-EI-Orbitrap system. Hans Mol described the system as a highly promising technique to complement LC-Orbitrap and enabling new comprehensive workflows for quantitative analysis of targeted compounds and qualitative screening of untargeted compounds for both GC and LC amenable pesticides.
Dr. Mol specifically highlighted the advantages of excellent mass accuracy (<1ppm) for each scan across a peak in a complex matrix, at a resolving power (RP) of 60,000, and the simplicity of one acquisition event to get multiple accurate mass ions that can make use of existing EI-MS libraries (such as NIST and Wiley). Watch Dr. Mol and other experts talk about this new system on our webpage dedicated to the new system at Thermoscientific.com/QExactiveGC.
Resolving Power of Mass Spectrometry
You can read more about the mass accuracy, acquisition rate at high resolving powers, linearity, detectability, accuracy, precision and identification capability observed in initial experiments by Dr. Mol in the following downloadable Application Note, High Efficiency, Broad Scope Screening of Pesticides Using Gas Chromatography High Resolution Orbitrap Mass Spectrometry (downloadable PDF).
As the application note describes, the resolving power of the mass spectrometer becomes a key factor in reliable pesticide detection as the sample types increase in complexity. The experiment demonstrates that 60K RP (m/z 200, full width half maxima, FWHM) was required to obtain reliable results for pesticides spiked into animal feed. In conclusion, the results indicate that the new Q Exactive GC Orbitrap MS system, in combination with the Thermo Scientific TraceFinder software, is an extremely effective tool for the routine screening of pesticides in food and feed samples.
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Different Approaches in Pesticides Screening
At the Pesticides Symposium, Prof. Jana Hajslova also presented on the use of GC-Q-Orbitrap in two different approaches for pesticide screening. The first approach focused on the targeted screen for pesticides from a customized HRAM database and a fast review of data using the TraceFinder software.
The second approach involved non-targeted screening via deconvolution of accurate mass data and spectral library matching with identification using accurate mass fragments. In the course of her presentation, Jana stated “When analyzing pesticides in whiskey samples, to my surprise, many compounds where automatically identified.”
Applications & Resources on GC Orbitrap MS Technology
I am also pleased to share some newly released applications, technical notes, and a white paper on experiments conducted with the new system:
- Application Note, titled, Fast Screening, Identification, and Quantification of Pesticide Residues in Baby Food Using GC Orbitrap MS Technology, (downloadable PDF) demonstrates the Q Exactive GC system has the quantitative power of a GC triple quadrupole MS combined with the high precision, full scan high resolution/accurate mass capability that only Orbitrap technology can offer.
- Technical Note, titled, High Mass Resolution is Essential for Confident Compound Detection, (downloadable PDF), describes how excellent sub-ppm mass accuracy accelerates the identification of unknown peaks by allowing the use of narrow mass tolerances to reduce the number of suggested elemental compositions.
- White Paper, titled, The Power of High Resolution Accurate Mass Using Orbitrap Based GC-MS (downloadable PDF) demonstrates the extremely consistent mass accuracy achieved across a chromatographic peak, at low and high concentrations, at low and high masses, and for various compound classes and matrix types.
- Application Note, titled, Untargeted Metabolomics Using Orbitrap-Based GC-MS (downloadable PDF) shows how routine ultra-high resolution and consistent sub-ppm accurate mass measurements offer reliable and selective analysis of a variety of metabolites present in a complex biological decomposition matrix.The authors Stefan Weidt (Glasgow Polyomics, University of Glasgow, Glasgow, UK) et al, stated that excellent chromatographic resolution and reproducible chromatographic separation together with fast data acquisition make the Q Exactive GC system an ideal platform for complex metabolomics analysis.
For years, scientists have been challenged by the limitations posed with existing GC-HRMS systems and felt the need for a high-resolution accurate mass (HRAM) system in fields ranging from food safety, to metabolomics to industrial, clinical, and pharmaceutical analysis. Given some of the feedback (link to downloadable PDF of brochure on system) we are hearing from leading scientists, I feel this system does address many of the limitations experienced with existing GC-HRMS systems and signals the start of a new chapter in GC-MS analysis.
Do let me know if I can answer any questions on this new system for you! I look forward to hearing from you.