DETERMINATION OF PESTICIDE RESIDUES IN QUECHERS EXTRACTS OF FRUIT COMMODITIES BY GC-MS/MS

Significance of the Topic

Ensuring the safety of fruit commodities requires sensitive and reliable analytical methods to detect pesticide residues at trace levels. Regulatory limits for maximum residue levels (MRLs) demand robust multiresidue screening techniques that can handle diverse matrices and deliver rapid turnaround in routine monitoring laboratories.

Objectives and Study Overview

This work evaluates a gas chromatography–tandem mass spectrometry (GC-MS/MS) protocol for quantifying pesticide residues in QuEChERS extracts of apple and raisin samples. Key goals included establishing a broad-scope multiresidue method with minimal optimization, achieving linear detection at low part-per-billion concentrations, and demonstrating compliance with European SANTE guidelines for accuracy and precision.

Methodology and Instrumentation

Sample preparation followed the QuEChERS CEN method: 5 g of organic apple or rehydrated raisin matrix underwent extraction with acetonitrile and salting-out, followed by dispersive solid-phase extraction (d-SPE) cleanup using primary–secondary amine (PSA) and magnesium sulfate. Extracts were evaporated to dryness, reconstituted in ethyl acetate, and post-spiked with a pesticide standard mix.

Used Instrumentation

• Gas Chromatograph: Agilent 7890 equipped with an Rtx-5MS column (30 m × 0.25 mm × 0.25 µm)
• Carrier Gas: Helium at 1.4 mL/min
• Injection: 1 µL pulsed splitless using a Gooseneck splitless liner
• Oven Program: 91 °C (1 min) to 330 °C at 8.5 °C/min, hold 5 min, total run ~34 min
• Mass Spectrometer: Waters Xevo TQ-GC triple quadrupole with 70 eV electron ionization
• Source Conditions: 250 °C source temperature, 320 °C transfer line, 3.0 V source voltage
• Detection: Multiple Reaction Monitoring (MRM) transitions generated via the Quanpedia database

Results and Discussion

Utilizing the Quanpedia library enabled rapid method setup by automatically assigning at least two MRM transitions per pesticide. Matrix-matched calibrations showed excellent linearity (R2 > 0.993) for apples over 0.001–0.050 mg/kg and raisins over 0.002–0.100 mg/kg. Accuracy at three quality control levels remained within ±15% of target concentrations, and repeatability studies yielded relative standard deviations below 20% across all analytes, meeting SANTE 11813/2017 criteria.

Practical Benefits and Applications

The described GC-MS/MS protocol offers:

• Rapid establishment of multiresidue methods with minimal manual optimization
• High sensitivity for trace-level pesticide detection in complex fruit matrices
• Regulatory compliance with European MRLs and quality-control guidance
• Capability to screen over a thousand pesticides using a single analytical sequence

Future Trends and Opportunities

Advances are expected in database-driven mass spectrometric workflows, enhanced automation of sample preparation, and expansion of multiresidue scope to include emerging and transformation products. Integration with high-throughput data processing and machine learning may further streamline routine monitoring and improve detection of novel contaminants.

Conclusion

This study demonstrates that QuEChERS extraction combined with GC-MS/MS and the Quanpedia MRM database yields a robust, sensitive, and efficient multiresidue method for pesticide analysis in fruits. The approach fulfills stringent regulatory standards while offering adaptability for routine laboratory use.

References

1. European Commission (2016) EU Pesticide Database. Plant Protection Products. Accessed February 2018.
2. European Union Reference Laboratory—Fruits and Vegetables (2018) Multiresidue Method using QuEChERS followed by GC-QqQ/MS/MS and LC-QqQ/MS/MS for Fruits and Vegetables.
3. European Union (2017) SANTE 11813/2017: Guidance Document on Analytical Quality Control and Method Validation for Pesticide Residues Analysis in Food and Feed.