QuEChERS Dispersive Solid Phase Extraction for the GC-MS Analysis of Pesticides in Cucumber

Significance of the Topic

Pesticide residue monitoring in fruits and vegetables is critical for food safety, regulatory compliance and public health protection. The QuEChERS approach offers a rapid, cost-effective and environmentally friendly sample preparation technique that enables high-throughput extraction of multiple pesticide classes from complex matrices such as cucumber.

Objectives and Study Overview

This application note demonstrates the use of the QuEChERS dispersive solid phase extraction method, following the European EN15662 protocol, coupled to GC-MS analysis for quantifying a range of pesticides in cucumber. The study assesses method linearity, recovery rates and reproducibility at a spiked level of 50 ng/g.

Methodology and Instrumentation

• Sample Preparation: 10 g homogenized cucumber extracted with acetonitrile in the presence of MgSO₄, NaCl, and citrate salts under ice-bath conditions. After centrifugation, 11 mL of supernatant is cleaned using dispersive SPE tubes containing MgSO₄, PSA and C18 sorbents.
• Calibration and Spiking: Matrix-matched calibration standards prepared in the range 25–1000 ng/g using triphenylphosphine as internal standard. Recovery experiments performed in six replicates at 50 ng/g.
• GC-MS Conditions: Thermo Scientific TRACE GC Ultra with TraceGOLD TG-5MS column (30 m × 0.25 mm × 0.25 µm), helium carrier at 1.0 mL/min, PTV splitless injection, temperature program from 90 °C to 320 °C. Detection by ISQ single quadrupole MS in SIM mode (EI 70 eV).

Main Results and Discussion

Calibration curves for ten pesticides showed excellent linearity (R² > 0.99). Recoveries ranged from 75.2 % to 119.6 % with RSD values below 9 %, meeting typical regulatory criteria. Chromatographic resolution was high and matrix interferences were minimal after dispersive SPE cleanup.

Benefits and Practical Applications

• High sample throughput: up to eight samples in under 30 minutes
• Minimal solvent and sorbent usage reduces cost and environmental impact
• Broad applicability to a wide range of herbicides, fungicides, organophosphates and pyrethroids
• Robust performance in complex plant matrices, suitable for routine QA/QC laboratories

Future Trends and Applications

Advances in sorbent chemistries and miniaturized workflows may further reduce solvent consumption and enhance selectivity. Integration with high-resolution mass spectrometry and automated platforms will support faster turnaround and expanded analyte scope, including emerging contaminants.

Conclusion

The QuEChERS-GC-MS method described provides a reliable, efficient and reproducible protocol for pesticide residue analysis in cucumber. It achieves regulatory recovery and precision requirements while offering operational simplicity and high throughput.

References

1. Anastassiades M, Lehotay SJ, Stajnbaher D, Schenck FJ. J AOAC Int 86 (2003) 412.
2. European Standard EN15662:2008. Foods of plant origin – determination of pesticide residues using GC/MS and/or LC-MS/MS following acetonitrile extraction/partitioning and dispersive SPE.