Large scale screening and quantitation of pesticide residues in rice using GC-(EI)-MS/MS

Significance of the topic

Rice is a primary food source for over 60% of the global population. To protect consumer health and ensure trade compliance, routine monitoring of pesticide residues at the low levels required by the European Commission and FSSAI is essential. The application of a fast, reliable multi-residue screening and quantitation method addresses this need in food safety laboratories.

Objectives and Study Overview

The study aimed to develop and validate a single-run GC-EI-MS/MS method for the targeted screening and quantification of 159 pesticide compounds in rice. Validation followed SANTE guidelines and demonstrated compliance with European Commission and FSSAI maximum residue limits (MRLs).

Methodology and Instrumentation

The sample preparation used the QuEChERS protocol: 5 g homogenized rice, water acidified at 1% acetic acid, extraction with acetonitrile and salt partitioning (MgSO4, sodium acetate), followed by cleanup with PSA. Analysis employed a TRACE 1310 gas chromatograph coupled to a TSQ 9000 triple quadrupole MS in Timed-SRM mode. Quantitation and identification criteria included two or more SRM transitions per analyte, retention time tolerance ±0.1 min, ion ratio ±30%, linearity R² > 0.99, recovery 70–120%, precision < 20%.

Used Instrumentation

• Thermo Scientific TRACE 1310 GC with TriPlus RSH autosampler
• TraceGOLD TG-5SIL MS column (30 m × 0.25 mm × 0.25 µm)
• TSQ 9000 triple quadrupole GC-MS/MS with ExtractaBrite ion source and VPI NeverVent technology
• TraceFinder software v4.1 for data acquisition and processing

Main Results and Discussion

• Baseline separation of 159 pesticides; no matrix interferences observed.
• More than 12 data points per chromatographic peak ensured reliable integration.
• Limit of quantitation: 0.01 mg/kg in rice (signal-to-noise ≥ 15).
• Linearity across 0.005–0.1 mg/kg with R² > 0.99 and residuals < 20%.
• Recoveries at 0.01 and 0.05 mg/kg ranged from 76% to 116%, precision < 15% RSD.
• Repeatability over 50 injections: peak area RSD < 15%, retention time variation < 0.05 min.

Benefits and Practical Applications

• High-throughput screening and quantitation of a broad pesticide panel in a single 32 min run.
• Compliance with SANTE, EC, and FSSAI MRL requirements allows seamless reporting in regulatory and quality control settings.
• Robust instrument features (VPI NeverVent, auto-SRM, optimized dwell times) reduce downtime and simplify method transfer.

Future Trends and Opportunities

• Extension of the workflow to other high-starch or complex food matrices.
• Integration with high-resolution mass spectrometry for non-target screening of emerging contaminants.
• Automation of sample preparation and data review to increase laboratory throughput and reduce human error.
• Development of portable MS platforms for on-site rapid screening in agricultural settings.

Conclusion

The validated GC-EI-MS/MS method combining QuEChERS extraction and TSQ 9000 detection achieves reliable, high-throughput quantitation of 159 pesticides in rice at regulatory limits. Strong performance in linearity, sensitivity, accuracy, and precision supports its adoption in food safety laboratories.

References

1. Lehotay S.J.; Maštovská K.; Lightfield A.R. J. AOAC Int. 2005, 88, 615–630.
2. European Commission SANTE/11813/2017 Guidelines on analytical quality control.
3. FSSAI Manual for Food Safety, 17th Edition, 2017. Food Safety and Standards Authority of India.
4. European Commission EU Pesticides Database. plant/pesticides/eu-pesticides-database.