Mass Spectrometry Applications for Food Safety Analysis

Significance of the Topic

Worldwide regulatory bodies have set maximum residue limits (MRLs) for hundreds of pesticides in food commodities, often at default levels of 0.01 mg/kg (10 ppb). Ensuring compliance demands analytical methods that are rapid, sensitive at low ppb levels, selective against complex matrices and capable of screening hundreds of chemically diverse compounds in a single run.

Objectives and Study Overview

To develop and validate automated, multi-residue screening workflows for 45–510 pesticides spanning polar to nonpolar classes in various plant-derived foods (fruit preserves, red wine, jam, baby food, herbal products, produce, grapes, flour, and juices). The methods combine advanced sample preparation (QuEChERS, ASE/GPC, dispersive SPE, online Turbulent-Flow cleanup) with high-performance chromatography (GC or UPLC) and state-of-the-art mass spectrometry (triple quadrupole and high-resolution Orbitrap platforms).

Methodology and Instrumentation

• Sample Preparation: QuEChERS extraction followed by dispersive SPE or gel permeation cleanup; accelerated solvent extraction (ASE) with GPC; Transcend TLX automated online cleanup.
• Chromatography: TRACE 1310 GC with PTV backflush and splitless injection; UPLC with Hypersil GOLD aQ or Accucore columns.
• Mass Spectrometry: TSQ Quantum XLS/Ultra and Quantum Access MAX triple-quadrupole systems in timed-SRM/H-SRM/U-SRM modes for enhanced selectivity; Exactive Orbitrap high-resolution accurate-mass LC-MS for full-scan screening and structural confirmation; QED MS/MS for data-dependent confirmation.
• Calibration and Data Processing: Matrix-matched standards with internal standardization; TraceFinder software for automated method generation, quantitative processing, reporting and spectral library matching; AutoSRM for rapid SRM development.

Main Results and Discussion

• Detection Limits: Achieved instrument detection limits down to 0.1–5 ppb for most pesticides, meeting or exceeding EU and Japanese MRLs, including challenging thermally labile or polar compounds.
• Linearity and Accuracy: Calibration curves were linear (r² > 0.99) over three orders of magnitude. Recoveries in spiked matrices (jam, wine, baby food, herbal products, grapes, flour, produce) ranged 70–120% with RSDs < 15%.
• Selectivity Enhancements: H-SRM (0.2 Da Q1) and U-SRM (0.1 Da) modes on TSQ Quantum Ultra reduced matrix interference, improved signal-to-noise, and prevented cross-talk between coeluting transitions.
• High-Throughput Screening: Timed-SRM on TSQ 8000 enabled monitoring of > 300 transitions with optimized dwell times, yielding 100 samples/day workflows.
• Coverage: Combined GC-MS/MS and LC-MS/MS detected 516 of 524 pesticides below their MRLs in a single onion matrix study, with 288 compounds confirmed by both techniques.
• Non-Targeted Screening and HRMS: Exactive Orbitrap workflows screened 510 pesticides in 12 min runs, with > 50% detected at 1 ppb and accurate-mass confirmation of isobaric compounds at < 5 ppm mass error.

Benefits and Practical Applications

• Comprehensive Coverage: Simultaneous analysis of hundreds of pesticides, including GC-amenable and LC-amenable chemistries, with minimal sample prep steps.
• Robustness and Throughput: Automated cleanup and GC backflush extend column lifetime, reduce maintenance downtime, and enable > 100 samples/day productivity.
• Regulatory Compliance: Methods meet EU DG SANCO and national performance criteria for sensitivity, precision and ion-ratio confirmation at or below MRLs.
• Flexible Confirmation: QED MS/MS and high-resolution accurate-mass full-scan provide orthogonal structural confirmation alongside targeted quantitation.

Future Trends and Potential Uses

• Broader Screening: Expand compound libraries to include emerging pesticides and their metabolites, leveraging AutoSRM and HRMS suspect screening.
• Non-Targeted Analysis: Integrate non-targeted HRMS workflows for environmental contaminants and degradation products.
• Green Chemistry: Miniaturize extraction and reduce solvent volumes with further automation and online sample preparation.
• Data Analytics: Employ machine learning for chromatogram deconvolution, trend analysis and predictive risk assessment.

Conclusion

Advanced multi-residue pesticide screening methods combining automated sample prep, high-performance chromatography, and modern mass spectrometry platforms fulfill stringent regulatory requirements for hundreds of compounds at low ppb levels in complex food matrices. The workflows deliver robust, high-throughput capabilities, accurate quantitation, and orthogonal confirmation—providing a future-proof solution for food safety monitoring.

References

1. European Union Regulation EC 396/2005 on pesticide residues.
2. FDA Fruit and Vegetable Juices Monitoring Program, 2013.
3. Anastassiades M., Lehotay S., et al. AOAC Int. 2003, 86(2), 412–431.
4. European Commission SANCO/10684/2009: DG SANCO Method Validation.
5. The Japanese Positive List System, MHLW, 2006.
6. Comission Directive 2006/125/EC on processed cereal foods and baby foods.
7. H-SRM and U-SRM Modes, Thermo Fisher Scientific Application Notes.
8. Quantitation Enhanced by Data-Dependent MS/MS (QED), Thermo Fisher Scientific, 2010.