Overview: To screen for pesticide residues in a single analysis and at a competitive cost, most laboratories rely on targeted analytical approaches using gas and liquid chromatography coupled to mass spectrometry instrumentation. Targeted screening methods require optimization of acquisition parameters for compounds, and monitoring of acquisition time windows. The scope of analysis can be increased using high-resolution full-scan mass spectrometry, in which a generic full-scan acquisition is run, followed by targeted data processing of a list of compounds within a database.
Method: The performance of the Thermo Scientific™ Q Exactive™ GC hybrid quadrupole-Orbitrap mass spectrometer (MS) is evaluated for the accurate screening of GC-amenable pesticides in cereals, feed, and fruits/vegetables. Sample extraction is performed using an acetate buffered QuEChERS-based approach. The Q Exactive GC system is operated in EI full scan mode using 60,000 (FWHM m/z 200) resolving power. Additional experiments are run at resolutions of 15K, 30K, and 120K.
System Benefits: The Q Exactive GC Orbitrap GC-MS/MS provides high mass resolving power up to 120,000 (m/z 200) full width half maxima (FWHM) to facilitate highly accurate mass measurements and enable confident discrimination of co-eluting and isobaric compounds in complex samples. Fast scan speeds and a high intrascan dynamic range (>5000) facilitate the detection of trace compounds in the presence of high matrix components.
Results: The results of this evaluation demonstrate that the Q Exactive GC hybrid quadrupole-Orbitrap mass spectrometer, in combination with Thermo Scientific™ TraceFinder™ software, is an extremely effective tool for the routine screening of pesticides in food and feed samples. The Orbitrap mass spectrometer delivers excellent resolving power, mass accuracy, and sensitivity for pesticides analysis.
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