A selective and sensitive method for quantification of pesticide residues in wheat using GC-(EI)-MS/MS

Significance of the Topic

Wheat is one of the most widely consumed cereal crops globally and contributes substantially to daily caloric intake. Intensive cultivation practices rely on diverse pesticides to protect yields and quality. Residual agrochemicals in wheat grains present potential health risks and must be monitored against regulatory limits set by bodies such as the European Commission (EC) and the Food Safety and Standards Authority of India (FSSAI). A robust analytical approach that balances sensitivity, selectivity, and throughput is therefore essential for food safety and compliance testing.

Study Objectives and Overview

The study demonstrates a comprehensive workflow for the simultaneous detection and quantification of 148 pesticide residues in a wheat matrix. The method combines QuEChERS extraction with gas chromatography–electron ionization triple quadrupole mass spectrometry (GC–EI–MS/MS) operated in timed‐selected reaction monitoring (t-SRM) mode. Validation was performed according to SANTE/11813/2017 guidelines, and results were evaluated against EC and FSSAI maximum residue levels (MRLs) for wheat.

Methodology and Instrumentation

• Sample Preparation and Cleanup: Wheat grains were ground to 250–500 µm, spiked for recovery studies, and extracted via QuEChERS using acidified water (1% acetic acid) and acetonitrile. Salts (MgSO₄, sodium acetate) facilitated phase separation, and primary secondary amine (PSA) sorbent removed polar interferences.
• GC–MS/MS Analysis: A Thermo Scientific TRACE 1310 GC with TriPlus RSH autosampler and a 30 m × 0.25 mm × 0.25 µm TraceGOLD TG-5SIL MS column was coupled to a TSQ 9000 triple quadrupole MS with an ExtractaBrite EI source and NeverVent VPI interlock. The method used splitless injection (1 µL at 280 °C), helium carrier at 1.2 mL/min, and a 32 min oven program.
• Data Acquisition and Processing: Acquisition in t-SRM with auto-optimized dwell times (2–10 ms) achieved ≥12 data points per peak. TraceFinder software applied SANTE acceptance criteria: ion ratio ±30%, retention time ±0.1 min, linearity (R² > 0.99), recovery 70–120%, and precision <20%.

Used Instrumentation

• Thermo Scientific TRACE 1310 Gas Chromatograph with TriPlus RSH autosampler
• Thermo Scientific TraceGOLD TG-5SIL MS column (30 m × 0.25 mm × 0.25 µm)
• Thermo Scientific TSQ 9000 Triple Quadrupole Mass Spectrometer with ExtractaBrite EI source and NeverVent VPI technology
• TraceFinder Software for automated SRM scheduling and data processing

Main Results and Discussion

The method achieved limits of quantitation (LOQs) of 0.005 mg/kg for the majority of analytes, corresponding to signal-to-noise ratios ≥12. Calibration curves exhibited R² > 0.99 across 0.001–0.100 mg/kg. Matrix-matched calibration compensated for >20% matrix effects and delivered recoveries of 71–110% with precision <18% RSD at LOQ, LOQ×2, and LOQ×10 levels. Automated dwell time scheduling maintained data quality for trace-level compounds while supporting all 148 transitions in a single injection.

Benefits and Practical Applications

This integrated QuEChERS–GC–EI–MS/MS workflow enables high-throughput screening of a broad pesticide panel in wheat. Compliance with SANTE guidelines and EC/FSSAI MRLs ensures reliable decision-making in commercial food testing and regulatory monitoring. Features such as VPI NeverVent and auto-SRM dwell time assignment reduce downtime and method development effort, supporting up to 38 injections in a 24-hour cycle.

Future Trends and Opportunities

Advances may include extension to multi-matrix workflows (e.g., flour, processed products), integration with high-resolution mass spectrometry for non-target screening, and automated sample preparation solutions. Emerging technologies in miniaturized GC-MS systems and machine learning-driven data processing hold potential to further streamline pesticide residue analysis.

Conclusion

The validated GC–EI–MS/MS method provides sensitive, selective, and robust quantification of 148 pesticide residues in wheat. Its compliance with international guidelines and high throughput make it well suited for routine food safety testing and regulatory enforcement.

References

• European Commission SANTE/11813/2017 Guidance on analytical quality control and method validation for pesticide residues analysis in food and feed.
• FSSAI Manual for Food Safety, 17th Edition (2017), Food Safety and Standards Authority of India.
• AOAC Official Method 2007.01: Pesticide Residues in Foods by Acetonitrile Extraction and Partitioning with Magnesium Sulfate.
• Central Insecticide Board and Registration Committee (CIBRC), Government of India, list of registered insecticides (as of 31 Dec 2018).
• European Commission Pesticides Database: Maximum Residue Levels for Wheat.