Fast, Simple QuEChERS Extraction and Cleanup of Pesticide Residue Samples

Importance of the Topic

Accurate and efficient determination of pesticide residues in food commodities is essential for protecting public health, ensuring compliance with regulatory limits and optimizing laboratory workflows. Traditional sample preparation techniques for pesticide analysis often involve extensive solvent use, multiple cleanup steps and time-consuming solid phase extraction. The QuEChERS method addresses these challenges by offering a faster, simpler, cost-effective and environmentally friendly alternative.

Aims and Overview

This work illustrates the application of the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) protocol for multiresidue analysis of pesticides in strawberries. Objectives include demonstrating a four-fold increase in sample throughput, significant reduction of solvent and materials costs, and robust cleanup performance using dispersive solid phase extraction (dSPE).

Methodology and Instrumentation Used

The QuEChERS workflow comprises three main steps:

• Sample extraction: Ten grams of homogenized strawberries are shaken with 10 mL acetonitrile and salting-out agents (MgSO4, NaCl, citrate buffers) to partition analytes into the organic phase. Surrogate standards monitor recovery efficiency.
• Extract cleanup: A 1 mL aliquot is subjected to dSPE in 2 mL polypropylene tubes preloaded with MgSO4 and sorbents (PSA, C18 or GCB) to remove water, organic acids, sugars, pigments and fats.
• Instrumental analysis: Cleaned extracts are optionally pH-adjusted and solvent-exchanged for GC-MS or LC-MS determination. Internal standards are added prior to injection.

Instrumentation:

• Shimadzu AOC-20i autosampler
• Shimadzu GC-MS QP-2010 Plus with electron ionization and selected ion monitoring
• Rtx-CLPesticides2 column (20 m × 0.18 mm × 0.14 µm) operated 40 °C to 320 °C at 12 °C/min
• Q-sep™ 3000 centrifuge for phase separation and dSPE cleanup

Main Results and Discussion

Primary secondary amine (PSA) sorbent provided effective removal of sugars, organic acids and anthocyanin pigments from strawberry extracts. Adding C18 controlled nonpolar interferences and fats without significant loss of hydrophobic pesticides. Graphitized carbon black (GCB) achieved decolorization but reduced recoveries of planar pesticides such as chlorothalonil and thiabendazole. Single-point calibration at 200 ng/mL yielded percent recoveries versus PSA baseline in the 97–160 % range for over 30 target compounds (organophosphates, carbamates, organochlorines and pyrethroids).

Benefits and Practical Applications

• Throughput acceleration: Sample processing time reduced from ~120 to ~30 min for six samples.
• Cost savings: Solvent consumption drops by 6–9×; no specialized glassware required.
• Flexibility: Sorbent selection (PSA, C18, GCB) tailors cleanup to specific matrix interferences.
• Regulatory compliance: Validated against AOAC 2007.01 and European EN 15662 methods.

Future Trends and Opportunities

Continued advancements in QuEChERS focus on miniaturization of extraction volumes, integration with automated platforms, development of novel sorbent chemistries for challenging matrices and expansion to non-polar analytes such as environmental pollutants. Coupling QuEChERS with high-resolution mass spectrometry promises enhanced sensitivity and broader multiresidue coverage.

Conclusion

The QuEChERS methodology offers a streamlined, robust and economical approach to pesticide residue analysis in fruits and vegetables. By combining simple extraction, rapid dispersive cleanup and established instrumental techniques, laboratories can achieve high throughput, low cost and reliable performance while minimizing solvent use and laboratory waste.

References

1. Michelangelo Anastassiades, Steven J. Lehotay, Darinka Štajnbaher, Frank J. Schenck. Fast and Easy Multiresidue Method Employing Acetonitrile Extraction/Partitioning and Dispersive Solid-Phase Extraction for the Determination of Pesticide Residues in Produce. J. AOAC International, 2003, 86(2):412–431.
2. AOAC Official Method 2007.01. Pesticide Residues in Foods by Acetonitrile Extraction and Partitioning with Magnesium Sulfate.
3. Schenck F.J. SPE Cleanup and Analysis of PPB Levels of Pesticides in Fruits and Vegetables. Florida Pesticide Residue Workshop, 2002.