A robust and sensitive method for the determination of pesticides in surface and ground water by triple quadrupole GC-MS

Importance of the topic

Monitoring trace levels of pesticides in surface and groundwater is essential to safeguard public health and ecosystems. Regulatory limits are becoming more stringent, driving demand for analytical methods that combine sensitivity, robustness and high throughput to support environmental monitoring and compliance testing.

Objectives and study overview

This work aimed to develop and validate a single-run GC-MS/MS method capable of quantifying approximately 350 pesticides in water at or below regulatory limits. Key goals included minimizing runtime, achieving low limits of quantitation, improving instrument uptime and simplifying quality control processes for routine testing laboratories.

Methodology

The optimized method uses a Thermo Scientific™ TRACE 1610 GC with a TraceGOLD™ TG-Contaminants 15 m × 0.25 mm, 0.10 µm column. A Thermo Scientific™ iConnect™ Thermospray SSL (TSI) injector permits 3 µL injections of DCM containing PEG analyte protectant. Chromatographic separation is completed in 18.33 minutes under helium flow. Detection is performed on a TSQ™ 9610 triple quadrupole MS equipped with NeverVent™ AEI ion source, EvoCell collision cell and XLXR detector. Time-scheduled selected reaction monitoring (t-SRM) with dwell-time prioritization and 35 eV electron energy delivers enhanced sensitivity and selectivity. Sample preparation concentrates water extracts by a factor of 500.

Used Instrumentation

• Thermo Scientific TRACE 1610 gas chromatograph
• TraceGOLD TG-Contaminants GC column (15 m × 0.25 mm × 0.10 µm)
• Thermo Scientific iConnect Thermospray SSL injector
• Thermo Scientific TSQ 9610 triple quadrupole mass spectrometer
• NeverVent AEI ion source and EvoCell collision cell

Main results and discussion

• Limits of quantitation in water ranged from 0.001 to 0.03 µg/L, corresponding to extract LOQs of 0.5–15 µg/L, meeting or beating established regulatory thresholds.
• Dwell-time prioritization increased signal-to-noise by up to threefold for critical analytes without extending runtime.
• Over 70 injections of matrix extracts bracketed by QC standards (5 and 10 µg/L) yielded peak area ratio RSDs below 10%, demonstrating excellent method robustness.
• No maintenance or MS retuning was required over 150 continuous injections, supporting uninterrupted high-throughput operation.

Benefits and practical applications

• Capability to screen and quantify ~350 pesticides in a single 18-minute run maximizes sample throughput.
• The robust injector and inert liner reduce downtime and maintenance costs in routine laboratories.
• Low LOQs and high selectivity enable reliable compliance with evolving regulatory standards.
• Simple QC workflow and automated SRM scheduling facilitate adoption across contract testing, environmental monitoring and QA/QC settings.

Future trends and applications

Advances in microfluidic injection, column chemistries and collision cell designs will further accelerate multiresidue analyses. Integration of automated sample preparation and AI-driven data review promises to streamline workflows. Emerging regulations on new pesticide classes will drive expansion of compound libraries and dynamic SRM scheduling.

Conclusion

The described GC-MS/MS method delivers a powerful solution for routine determination of hundreds of pesticides in water. By combining rapid separation, enhanced sensitivity, robust injector technology and unattended operation, laboratories can achieve high productivity, cost-efficiency and confidence in trace-level quantitation.

References

1. Gauriat B, Thomas D, Garnier J-F. Improving routine testing of difficult-to-analyze pesticide residues using a TraceGOLD TG-Contaminants column with GC-MS/MS. Thermo Fisher Scientific Application Note 000019; 2021.
2. Mastovská K, Lehotay SJ, Anastassiades M. Combination of analyte protectants to overcome matrix effects in routine GC analysis of pesticide residues in food matrices. Analytical Chemistry. 2005;77(24):8129–8137.
3. Morgan P. Gas Chromatography Liner Selection Guide. Thermo Fisher Scientific Technical Note 20551; 2020.
4. Restek. Solvent Expansion Calculator. Restek Tools and Calculators; accessed 2022.
5. Directive 2000/60/EC. Establishing a framework for Community water policy. Official Journal of the European Communities; 2000.