Analysis of Pesticides in Food Matrix using QuEChERS by Triple Quadrupole GC/MS/MS and LC/MS/MS

Significance of the Topic

The increasing complexity of global food trade and divergent national maximum residue limits (MRLs) for pesticides drive the need for fast, reliable and sensitive analytical methods. Implementation of positive list systems in key markets and harmonization efforts demand methods capable of screening hundreds of active substances at trace levels. The QuEChERS approach combined with triple quadrupole GC/MS/MS and LC/MS/MS offers a versatile solution for comprehensive pesticide residue monitoring in diverse food matrices.

Objectives and Overview of the Study

This work aimed to verify the performance of recommended analytical workflows for the 138 pesticides prioritized by the European Union Reference Laboratory (EURL). Of these, 66 compounds were assigned to GC/MS/MS analysis and 72 to LC/MS/MS. Using Shimadzu’s GCMS-TQ8030 and LCMS-8040 instruments, the study assessed sensitivity, selectivity, repeatability and recovery in representative food samples (leek and paprika) prepared via the QuEChERS protocol.

Used Methodology and Instrumentation

The core sample preparation and analysis steps included:

• QuEChERS pretreatment: acetonitrile extraction, salting-out (MgSO₄, NaCl, citrate salts), followed by dispersive SPE cleanup (PSA, ENVI-Carb).
• GC/MS/MS analysis on GCMS-TQ8030: Rxi-5Sil MS column, helium carrier gas in constant linear velocity mode, splitless injection, MRM and SIM modes for comparison. Interface temperature 250 °C, ion source 230 °C.
• LC/MS/MS analysis on LCMS-8040: Nexera UHPLC with Shimpack-XR ODS II column, gradient elution (ammonium formate/formic acid in water and methanol), flow rate 0.2 mL/min, column oven 40 °C. ESI in positive/negative mode with rapid polarity switching and 276 MRM transitions.

Main Results and Discussion

GC/MS/MS evaluation demonstrated:

• Detection limits below 1 ppb for representative pesticides, with signal-to-noise ratios exceeding 20.
• Superior selectivity in MRM vs SIM, effectively mitigating matrix interferences in paprika extracts.
• Excellent repeatability (%RSD < 7% for 10 ppb spikes, n=6) across all 66 GC-assigned compounds.

LC/MS/MS findings included:

• Linear calibration (r² > 0.999) over 1–1000 ppb for typical analytes.
• Recoveries of 80–110% in both leek and paprika at 5 ppb spike levels, despite complex co-extractives.
• Robust repeatability for 72 LC-assigned pesticides, with most %RSD values below 15%.

Combined, the two platforms enabled high-throughput, high-sensitivity screening of the full suite of 138 pesticides.

Practical Benefits and Applications

The validated workflow supports routine monitoring in food safety laboratories, offering:

• Compliance with international MRL regulations through a single comprehensive workflow.
• Rapid analysis times and straightforward method translation between laboratories.
• Cost-effective sample throughput enabled by QuEChERS simplicity and instrument robustness.

Future Trends and Potential Applications

Advances likely to enhance this approach include:

• Further acceleration of polarity switching and dwell time reduction for greater MRM multiplexing.
• Integration of high-resolution mass spectrometry for non-targeted screening alongside quantitative assays.
• Extension to additional matrices (grains, animal products) and emerging contaminants.
• Automation of QuEChERS workflows to increase laboratory throughput and reproducibility.

Conclusion

The combination of QuEChERS sample preparation with triple quadrupole GC/MS/MS and LC/MS/MS on Shimadzu’s GCMS-TQ8030 and LCMS-8040 platforms provides a powerful, validated solution for multi-residue pesticide analysis. High sensitivity, selectivity and repeatability meet the stringent requirements of regulatory monitoring and support global harmonization efforts.

Reference

• Anastassiades, M. et al. (2003) QuEChERS: a simple, effective sample preparation method for pesticide residue analysis.
• European Union Reference Laboratory (EURL) report on multiresidue methods for fruits and vegetables.
• Shimadzu IMSC 2012 Poster PO-CON1216E: Multi-class pesticide analysis using fast MRM with polarity switching.