How to Find Unexpected Pesticides: A New High-Resolution Technique in Food Safety
Learn how the National Food Agency in Sweden has been using Orbitrap technology to enhance targeted and non-targeted pesticide detection into one platform
27 Jan 2017
Enhanced targeted and non-targeted pesticide detection is being used to screen foods for unexpected pesticides
In a presentation filmed at NACRW 2016, Susanne Ekroth, National Food Agency, Sweden, described the application of the Thermo Scientific™ Q Exactive™ Focus Hybrid Quadrupole-Orbitrap™ Mass Spectrometer, to the Swedish ethyl acetate (SweEt) extraction method, for pesticide residues detection in a variety of samples including fruit, vegetables, cereals and products of animal origin.
Susanne works to ensure food and drinking water safety, which includes the identification and quantification of pesticides. The analysis of pesticides presents many challenges, including the diversity of analytes, the wide range of concentrations encountered, and the number of different sample types, all with variable matrix complexity.
The multi-residue SweEt method, based on extraction with ethyl acetate, was developed by the agency to analyze pesticide residues in food samples. The extracts are injected directly in LC-MS/MS and GC-MS/MS for the quantification and identification of target pesticides. In addition, LC-MS TOF is used to screen separately for unexpected pesticides. The aim of this work was to investigate if the Orbitrap technology could enhance the workflow by enabling screening and quantitation to be done with one instrument, in the same injection.
Verification of the Q Exactive Focus Hybrid Mass Spectrometer Quadrupole-Orbitrap for use in the SweEt method showed good results for linearity, robustness and detectability using the full scan -vDIA* acquisition workflow.
Susanne describes vDIA as an interesting and flexible fragmentation option that is similar to the all ions fragmentation approach by virtue of the fact that it provides non-targeted fragmentation of all precursor ions available across the entire mass range. The main difference is that the entire mass range of interest is divided into a small number of mass segments, typically 5, each with a pre-determined mass range. The precursor ions in each segment are fragmented and the segments analysed consecutively to cover the entire mass range of interest. The result, she says, is that because fewer precursor ions are fragmented in each individual mass segment compared to the entire mass range, the spectra are less complex, selectivity is improved and interpretation of mass spectra is made much easier.
Susanne found the equipment user-friendly, with an easy automated workflow, and enjoys the possibilities it offers of sharing databases between colleagues to increase the number of analytes included in their methods. One major advantage she identifies is that Thermo Scientific is planning to develop new databases with retention times which “will make screening even easier”.
The equipment is user-friendly with an easy automated workflow.
Susanne Ekroth National Food Agency, Sweden
Another feature she highlights is the capability of retrospective analyses: you can store raw data files for years, and reprocess them with new methods to search for unexpected analytes, should new information come to light in the future. “An exciting development,” as Susanne notes.
The Swedish pesticide group developed the SweEt multi-residue method with a view to making it as easy and efficient as possible. “Nothing is more simple than greatness; indeed, to be simple is to be great” is a quote that, in Susanne’s view, is applicable not only to SweEt but also to the Orbitrap technology.
*vDIA is not available in the U.S.