Analysis of Pesticide Residues in Lettuce and Apple Samples using Agilent Bond Elut QuEChERS AOAC Extraction Kit with Universal Dispersive SPE

Importance of the Topic

Reliable detection of pesticide residues in produce is vital for food safety and regulatory compliance. The QuEChERS workflow streamlines sample preparation by combining extraction and cleanup, enabling efficient multiclass pesticide analysis.

Objectives and Study Overview

This study evaluates the performance of the Agilent Bond Elut QuEChERS AOAC extraction kit paired with a universal dispersive SPE cleanup for quantifying 26 pesticides in lettuce and apple matrices. Recoveries, linearity, and reproducibility were assessed at three spiking levels using GC/MS in SIM mode.

Methodology and Instrumentation

Sample Preparation

• Certified pesticide-free romaine lettuce and red delicious apples were homogenized and frozen prior to extraction
• Buffered extraction: 15 g sample with 15 mL acetonitrile (1 % acetic acid) and AOAC salt packet (6 g MgSO₄, 1.5 g sodium acetate)
• Universal dSPE cleanup: 1 mL extract treated with 150 mg MgSO₄, 50 mg PSA, 50 mg C18, 7.5 mg GCB

Instrumentation

• GC/MS: Agilent 7890 GC system with 5975C MSD
• Column: HP 5MS UI, 30 m × 0.25 mm × 0.25 µm
• Mode: SIM with target and qualifier ions
• Oven program: 70 °C to 280 °C with controlled ramps

Main Results and Discussion

Matrix blanks showed minimal interferences. Calibration curves for all pesticides displayed excellent linearity (r² > 0.995). Mean recoveries ranged between 85 % and 112 % across both matrices, with RSD values below 15 %. Hexachlorobenzene exhibited lower recoveries (ca. 60 %) due to adsorption on graphitized carbon black. SIM mode enhanced sensitivity and selectivity.

Benefits and Practical Applications

QuEChERS combined with universal dSPE offers a rapid, reproducible and cost-effective approach for routine pesticide monitoring in fruits. The method reduces solvent consumption, minimizes sample handling and is compatible with high-throughput GC/MS and LC/MS platforms, supporting QA/QC operations in food testing laboratories.

Future Trends and Potential Applications

• Extension of universal dSPE to diverse matrices such as meat, fish and soil
• Integration with tandem MS techniques (GC/MS/MS, LC/MS/MS) for enhanced confirmation
• Development of automated and miniaturized extraction workflows
• Tailoring sorbent chemistries to address emerging contaminants

Conclusion

The Agilent Bond Elut QuEChERS AOAC extraction kit with universal dispersive SPE delivers an efficient and robust cleanup for multiresidue pesticide analysis in lettuce and apple samples. Coupled with GC/MS in SIM mode, it enables accurate quantitation at part-per-billion levels with strong recoveries and reproducibility.

Reference

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