Targeted and Non-Targeted Pesticide Screening Using UPLC-Vion HDMSE in Complex Fruit and Vegetable Matrices

Significance of the Topic

The reliable screening of pesticide residues in fruits and vegetables is essential for food safety and regulatory compliance. Complex sample matrices combined with large lists of potential contaminants make traditional targeted methods laborious and risk missing unexpected residues. Coupling ultra–high-performance liquid chromatography with ion mobility separation and high-resolution mass spectrometry provides additional dimensions of separation and identification, increasing confidence in both targeted and non-targeted pesticide screening.

Objectives and Study Overview

This study aimed to evaluate a combined targeted and non-targeted pesticide screening workflow using UPLC-Vion HDMSE in complex fruit and vegetable extracts. Key objectives included:

• Detecting over 500 pesticides and metabolites in extracts of French green bean, strawberry, jalapeño, and mini sweet pepper.
• Assessing the value of collision cross section (CCS) measurements and full-spectrum acquisition (HDMSE) for compound confirmation.
• Demonstrating the ability to identify a novel pesticide not included in the initial screening library.

Methodology and Instrumentation

Sample Preparation:

• Modified QuEChERS extraction from fruit and vegetable matrices.
• Dilution of extracts in acetonitrile and water prior to injection.

Chromatographic Conditions:

• Two UPLC methods (Method A: BEH C18 column, ammonium acetate buffer; Method B: HSS T3 column, formic acid buffer).
• Injection volumes of 1 μL and 5 μL in triplicate to assess system performance and analyte response.

Mass Spectrometry Acquisition:

• Data-independent HDMSE acquisition combining low- and high-collision energy scans.
• Ion mobility separation to obtain CCS values for each ion.
• Lockmass calibration and regular QC injections to monitor mass accuracy, CCS reproducibility, and retention time stability.

Used Instrumentation

• Waters Vion IMS QTof Mass Spectrometer
• ACQUITY UPLC I-Class System
• ACQUITY UPLC BEH C18 and HSS T3 Columns
• UNIFI Scientific Information System for data processing and review

Main Results and Discussion

Targeted Screening:

• All expected compounds from a prior tandem quadrupole MS/MS analysis were detected and confirmed using criteria including mass error, CCS deviation, retention time difference, and presence of diagnostic fragments.
• Metabolites such as chlorpyrifos-oxon and imidacloprid desnitro were identified, although they were not reported in the earlier MS/MS dataset.

Adduct and Fragment Filtering:

• Custom UNIFI filters allowed conditional acceptance of +Na adducts when fragment ions were absent, reducing false negatives.

Method Comparison:

• Retention times shifted between Methods A and B, but CCS values remained consistent (<2% error), underscoring CCS as a robust identification parameter independent of chromatographic conditions.

Non-Targeted Discovery:

• A targeted halogen-matching and common fragment filter revealed an unknown ion at m/z 289.0554, later identified as the new butenolide insecticide flupyradifurone.
• Ion mobility spectral cleanup provided cleaner, drift-time aligned spectra, facilitating rapid identification of unknowns.

Benefits and Practical Applications of the Method

The integrated UPLC-Vion HDMSE approach delivers:

• Simultaneous targeted and non-targeted screening in a single run, maximizing laboratory throughput.
• CCS measurements as an orthogonal identifier to enhance confidence and reduce reliance on retention time alone.
• Automated data processing and review workflows in UNIFI for efficient handling of large screening libraries.
• Capability to detect novel or unexpected contaminants and rapidly update the screening library.

Future Trends and Potential Applications

Advances in ion mobility-HRMS are expected to drive broader adoption in food safety, environmental monitoring, and pharmaceutical quality control. Expanding CCS reference libraries, integrating multivariate suspect screening, and cloud-based data sharing will further enhance the detection of emerging contaminants and streamline regulatory workflows.

Conclusion

The combination of UPLC separation, HDMSE data acquisition, and ion mobility-derived CCS values provides a powerful platform for comprehensive pesticide screening in complex matrices. This workflow improves identification confidence, supports the discovery of new residues, and offers a scalable solution for evolving analytical demands.

Reference

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