Increasing productivity in pesticide residues analysis by GC-MS/MS with on-line automated micro solid phase extraction (μSPE) clean-up

Significance of the Topic

The accurate and efficient measurement of pesticide residues in food is essential for consumer safety, regulatory compliance, and quality control in agricultural supply chains. Traditional QuEChERS extraction followed by manual dispersive solid phase extraction (dSPE) often leaves matrix interferences that shorten instrument life and require frequent maintenance. Automating the clean-up step with on-line micro solid phase extraction (µSPE) integrated into an autosampler addresses these challenges by delivering cleaner extracts, reducing human error, and boosting laboratory productivity.

Objectives and Study Overview

This study aimed to evaluate an automated on-line µSPE clean-up workflow for QuEChERS extracts of fruit and vegetables prior to GC-MS/MS pesticide analysis. Key performance indicators included analytical accuracy, precision, linearity, instrument uptime, sample throughput, and labor time savings. A fully automated calibration preparation was also incorporated to assess end-to-end productivity gains.

Methodology and Instrumentation

Samples of apple, tomato, lemon, and onion were extracted using the QuEChERS EN 15662 protocol. A Thermo Scientific TriPlus RSH SMART autosampler performed on-line µSPE clean-up in two steps: conditioning a 45 mg cartridge (MgSO₄/PSA/C18/GCB blend) with acetonitrile and then loading and eluting 300 µL of raw extract at controlled flow. Eluates were injected (1 µL) into a TRACE 1610 GC coupled to a TSQ 9610 triple quadrupole MS/MS with an iConnect HeSaver-H2Safer SSL injector, using helium carrier gas and timed-SRM detection. Semi-procedural, matrix-matched calibration standards were diluted and processed identically on the autosampler.

• Autosampler: TriPlus RSH SMART with µSPE tools and ATC station
• GC: TRACE 1610 with HeSaver-H2Safer SSL Injector
• MS/MS: TSQ 9610 in Advanced EI mode, timed-SRM
• Software: Chromeleon CDS for sequence control and data processing

Main Results and Discussion

Automated µSPE provided significantly cleaner extracts compared to raw QuEChERS, as evidenced by reduced total ion current background. At spike levels of 0.01 and 0.05 mg/kg, over 97 % of 190 pesticides achieved recoveries within 70–120 % and RSDs below 20 %, meeting EU SANTE criteria. Linearity was confirmed across 0.005–0.200 mg/kg for most analytes, with a few exceptions requiring a narrower range. The prep-ahead capability allowed µSPE clean-up to run during the previous GC-MS analysis, minimizing idle time.

Benefits and Practical Applications of the Method

The automated on-line µSPE workflow delivers:

• Cleaner extracts that extend column and inlet lifetimes and reduce maintenance downtime
• Enhanced repeatability and reduced manual error through robotic sample handling
• Significant labor savings: approximately 1.5 hours saved when processing 60 samples, plus automated calibration dilution
• Unattended operation, enabling overnight and weekend runs
• Cost reductions in carrier gas use via HeSaver-H2Safer technology

Future Trends and Opportunities for Use

Emerging directions include the adaptation of on-line µSPE for diverse matrices beyond fruits and vegetables, integration with hydrogen carrier gas for further cost savings, and development of multi-blend cartridges targeting specific interference profiles. Coupling automated clean-up with advanced data analytics and remote monitoring could further streamline pesticide residue testing in high-throughput environments.

Conclusion

The automated on-line µSPE clean-up combined with GC-MS/MS analysis meets rigorous regulatory standards for pesticide residue detection while delivering cleaner extracts, robust quantitation, and substantial time and cost efficiencies. This approach enhances laboratory productivity and supports reliable food safety monitoring.

References

1. Anastassiades M, Lehotay SJ, Štajnbaher D, Schenck FJ. Fast and easy multiresidue method employing acetonitrile extraction/partitioning and “dispersive solid-phase extraction” for the determination of pesticide residues in produce. J AOAC Int. 2003;86(2):412–431.
2. Perestrelo R, Silva P, Porto-Figueira P, Pereira JAM, Silva C, Medina S, Câmara JS. QuEChERS—Fundamentals, relevant improvements, applications and future trends. Anal Chim Acta. 2019;1070:1–28.
3. Thermo Fisher Scientific. Reducing running costs for GC-MS/MS analysis of pesticide residues using hydrogen carrier gas. Application Note 002225.
4. European Commission. SANTE/11312/2021: Analytical quality control and method validation procedures for pesticide residues analysis in food and feed.
5. Thermo Fisher Scientific. Confident analysis of ultra-trace pesticide residues in baby food using triple quadrupole GC-MS. Application Note 000437.