Location: Chemistry ResearchTitle: Analysis of pesticides in plant foods by QuEChERS and gas chromatography-mass spectrometry: An undergraduate laboratory experiment
|HENGEL, MATT - University Of California, Davis|
|WONG, JON - Us Food & Drug Administration (FDA)|
|REDMAN, ZACHARY - University Of California, Davis|
|WILLIAMS, KATRYN - New York State Department Of Environmental Conservation|
Submitted to: Journal of Chemical Education
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/3/2019
Publication Date: 12/24/2019
Citation: Rering, C.C., Williams, K.L., Redman, Z.C., Hengel, M.J., Wong, J.W. 2019. Analysis of pesticides in plant foods by QuEChERS and gas chromatography-mass spectrometry: An undergraduate laboratory experiment. Journal of Chemical Education. 2020, 97, 1, 226–233. https://doi.org/10.1021/acs.jchemed.9b00476.
Interpretive Summary: Providing college students realistic and hands-on laboratory courses in environmental chemistry can be challenging due to time and resource limitations. This paper describes and promotes an undergraduate laboratory experiment that adopts current, sophisticated techniques for analyzing pesticide residues in food, including the so-called “QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) procedure” followed by gas chromatography-mass spectrometry detection. The experiment was popular among students and re-enforced key analytical chemistry concepts covered in the corresponding lecture.
Technical Abstract: A laboratory experiment was developed for an undergraduate environmental chemistry laboratory course to analyze pesticides in plant foods, such as fresh fruits and vegetables. Students were exposed to the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) procedure, a two-step process that is commonly used in pesticide laboratories that involves acetonitrile salt-out extraction of the produce sample, followed by a solid-phase dispersive clean-up procedure using a combination of sorbents. The cleaned extract was solvent exchanged into toluene and analyzed by capillary gas chromatography-mass spectrometry in selective ion monitoring (SIM) mode (GC-MS/SIM) for selected pesticides. Students utilized QuEChERS to analyze spiked and incurred pesticide residues in plant foods and applied GC-MS for the quantitation and identification of pesticides. Students were exposed to several chemistry, laboratory, and instrumental concepts in this experiment such as liquid-solid and solid-phase extraction, some aspects of method validation, and the advantages of mass spectrometry over non-selective detection techniques. This experiment received favorable responses from the students because of the “real world” applicability of the QuEChERS procedure, the powerful use of GC-MS for analysis, and concepts transferred from lecture to the laboratory.