Waters Application Notes - Food Testing

Importance of the Topic

Reliable, sensitive, and high-throughput analysis of pesticide residues is vital to ensure the safety and compliance of the global food supply. Highly polar, anionic, acidic, and neutral compounds present unique analytical challenges in diverse matrices such as cereals, fruits, vegetables, and plant-derived products. Recent advances in UPLC-MS/MS and GC-MS/MS, coupled with streamlined sample preparation and cleanup techniques, allow laboratories to meet stringent regulatory limits with reduced development time and cost.

Objectives and Study Overview

• Develop direct extraction and UPLC-MS/MS methods to quantify highly polar cationic pesticides and plant growth regulators in cereals, fruit, and vegetables using the QuPPe protocol and a HILIC-based ACQUITY UPLC BEH Amide column.
• Optimize anionic polar pesticide analysis in wheat flour using QuPPe extraction, freezing-out, and a Torus DEA column on UPLC-MS/MS.
• Apply a simple pass-through cleanup with Oasis PRiME HLB to QuEChERS extracts of high-fat, high-pigment matrices (edamame) prior to UPLC-MS/MS analysis of free acidic herbicides.
• Implement a multi-residue GC-MS/MS method on the Xevo TQ-GC for determination of 208 pesticide residues and metabolites in fruits, vegetables, cereals and nuts following the new Chinese national standard GB 23200.113-2018.

Methodology and Instrumentation

• Sample Preparation: QuPPe for polar pesticides, QuEChERS for non-polar and acidic herbicides, with modifications such as freezing out (–20 °C) and dispersive SPE (DisQuE pouch).
• Cleanup Strategies: Pass-through SPE with Oasis PRiME HLB cartridges effectively removes fats, phospholipids, and pigments without retaining target analytes; no graphitized carbon black required.
• Chromatography: ACQUITY UPLC I-Class or H-Class Bio systems with BEH Amide (HILIC) or Torus DEA columns for MS analysis; reverse-phase ACQUITY HSS-T3 column for acidic herbicides; Rtx-1701 GC column for volatile pesticides.
• Mass Spectrometry: Xevo TQ-S micro, TQ-XS, and TQ-GC tandem quadrupole platforms; ESI+ and ESI– ionization for UPLC-MS/MS, EI 70 eV for GC-MS/MS; IntelliStart automated MRM optimization; TargetLynx Application Manager and Quanpedia database for rapid method setup and processing.

Main Results and Discussion

• Highly Polar Cationic Pesticides: Achieved retention times >2× void volume, excellent peak shapes, stable retention (<±0.1 min), linear calibration (r²>0.995) over 0.002–0.200 mg/kg, recoveries 85–115%, RSD<5% at 1–20 ng/mL.
• Anionic Polar Pesticides: Torus DEA column provided robust retention of glyphosate, AMPA, glufosinate, fosetyl-Al, phosphonic acid, and related metabolites; matrix-matched calibration (0.005–0.250 mg/kg) with r²>0.997, residuals <20%, recoveries 80–120%, RSD<10%.
• Acidic Herbicides in Edamame: Oasis PRiME HLB cleanup removed ≥95% phospholipids and pigments; recoveries of free acidic herbicides ranged 70–120% at 1–100 ng/g, RSD<15%; simplified workflow enabled multi-class analysis of acidic, neutral, and basic pesticides from one extract.
• Multi-Residue GC-MS/MS (208 Analytes): The combined QuEChERS–Oasis PRiME HLB protocol on Xevo TQ-GC met GB 23200.113-2018 requirements. In-house verification in cucumber (0.01 mg/kg), grape (0.01 mg/kg), and rice (0.02 mg/kg) showed retention times ±0.1 min, ion ratios within ±30%, recoveries 70–120%, RSD<20%, LOQs ≤ MRLs.

Benefits and Practical Applications

• Single extraction protocols support multi-class pesticide screening with minimal method development and maintenance costs.
• Automated MRM optimization and preconfigured Quanpedia methods accelerate method transfer and updates.
• CLEANUP with Oasis PRiME HLB reduces instrument downtime and consumable turnover by removing problematic co-extractives.
• Compliance with international guidelines (SANTE, EURL-SRM QuPPe, GB standards) ensures data integrity for regulatory and QA/QC laboratories.

Future Trends and Applications

• Integration of ion mobility spectrometry (IMS) in routine workflows to enhance isomer separation and confidence in identification.
• New column chemistries tailored for ultra-polar and zwitterionic compounds to broaden analyte scope.
• High-throughput screening using data‐independent acquisition (DIA) on QTof platforms for comprehensive residue profiling.
• Automated sample preparation and miniaturized workflows to further decrease solvent usage and increase laboratory productivity.

Conclusion

Advanced combinations of QuPPe and QuEChERS extractions, selective SPE cleanup, high-performance UPLC and GC separations, and sensitive tandem quadrupole platforms provide robust, accurate, and efficient workflows for pesticide residue analysis across diverse food matrices. These strategies meet or exceed regulatory requirements, reduce training and operational costs, and protect public health through reliable monitoring of complex analytes.

Reference

• European Commission EURL-SRM QuPPe Method (2017).
• Waters Guide to HILIC Chromatography (2014).
• EU SANTE Guidance 11813/2017 on Pesticide Residue Analysis (2017).
• GB 23200.113-2018 National Standard for Pesticide Residues by GC-MS/MS (2018).
• Lehotay S. J. AOAC Int. 2005;88(2):595–614.