High Precision Pesticide Analysis in Produce using GC Triple Quadrupole and U-SRM Mode

Significance of the Topic

Monitoring pesticide residues in agricultural produce is critical to ensure food safety and regulatory compliance with stringent maximum residue levels around 0.01 mg/kg. Advanced analytical approaches enable rapid screening of diverse pesticides at trace levels across multiple food matrices while maintaining cost-effectiveness and throughput.

Study Objectives and Overview

This work demonstrates a comprehensive multi-residue GC-MS/MS method for over 400 pesticides in produce like wheat, cucumber, and blackcurrant. The aim is to achieve sensitive quantification down to 0.001 mg/kg using a generic QuEChERS extract coupled with the Thermo Scientific TSQ Quantum XLS Ultra system. Key performance metrics include calibration linearity, repeatability, ion ratio stability, and selectivity enhancements.

Methodology

Sample preparation employs the QuEChERS protocol with acetonitrile extraction and dispersive SPE. Following extraction, solvent exchange ensures compatibility with GC injection. Calibration uses blank QuEChERS cucumber extract spiked at levels from 0.001 to 0.01 mg/kg. Each pesticide is monitored by at least two timed SRM transitions to improve selectivity and data reliability.

Instrumentation

• Gas chromatograph: TRACE GC Ultra with B.E.S.T. PTV injector and backflush device
• Autosampler: Thermo Scientific TriPlus RSH
• Column: TraceGOLD TG-5MS (30 m, 0.25 mm i.d., 0.25 µm film) with a 1.2 m TG-5HT pre-column
• Mass spectrometer: TSQ Quantum XLS Ultra with EI ionization (70 eV), HyperQuad technology, and U-SRM capability (0.1 Da Q1 resolution)

Key Results and Discussion

The method achieves reliable detection at 1 ppb (0.001 mg/kg) with linear calibration coefficients above 0.995 and residual errors below 10%. The system shows repeatability with RSDs typically under 9% for challenging analytes such as Captan and Folpet. Backflush operation protects the analytical column and injector liner, enhancing robustness and reducing maintenance frequency. U-SRM acquisitions provide superior selectivity by narrowing Q1 resolution to 0.1 Da, effectively reducing matrix interferences in complex samples like wheat.

Practical Benefits and Applications

• High-throughput analysis with fast turnaround (< 48 h) using small sample volumes
• Reduced maintenance and column downtime via concurrent PTV backflush
• Enhanced selectivity and sensitivity through timed SRM and U-SRM modes
• Minimal cleanup requirements maintain low cost and simple workflow

Future Trends and Opportunities

Further developments may include expanded U-SRM adoption for broader compound coverage, integration of automated data processing with artificial intelligence, advanced sample cleanup strategies to reduce matrix effects, and wider application to emerging contaminants. Continuous improvement in mass analyzer resolution and robustness will support regulatory demands and complex matrix analyses.

Conclusion

The combination of QuEChERS extraction with the TSQ Quantum XLS Ultra GC-MS/MS system delivers a powerful multi-residue method, offering high sensitivity, robustness, and selectivity for routine pesticide monitoring. Performance metrics meet and exceed regulatory requirements, making this workflow suitable for high-throughput food safety laboratories.

Reference

1. REGULATION (EC) No 396/2005 and amendments, Feb. 23 2005
2. M. Anastassiades, S. Lehotay, D. Steinbacher, F. Schenck, J. AOAC Int. 86(2) 412 (2003)
3. Munari F., Huebschmann H.J., Application Note 51888, Thermo Fisher Scientific (2010)
4. Pesticides Method Reference, 2nd ed., Thermo Fisher Scientific (2011)