Analysis of multiple pesticide residues in salad using triple quadrupole GCMS/MS system

Importance of the Topic

The widespread use of pesticides in agriculture necessitates robust analytical methods to monitor residue levels in foods, especially salads consumed raw. Ensuring compliance with regulatory limits protects public health and facilitates international trade.

Objectives and Study Overview

This study aimed to develop a rapid, sensitive and reliable method for simultaneous quantification of over 100 pesticide residues in both raw and cooked salad matrices. Key tasks included:

• Optimizing sample extraction via QuEChERS protocol
• Establishing GC-MS/MS parameters for efficient multi-residue analysis
• Evaluating the impact of thermal processing on pesticide levels

Methodology

Pesticide extraction employed the QuEChERS approach:

• 5 g homogenized salad sample spiked at 100 ppb, followed by water addition
• Acetonitrile extraction and salt-induced partitioning using MgSO4
• dSPE cleanup with MgSO4, PSA and C18 sorbents
• Filtration through 0.22 µm filter prior to analysis

Instrumentation Used

The analysis utilized the Shimadzu GCMS-TQ8030 triple quadrupole system with:

• High-speed Scan/MRM acquisition at 20,000 u/s and Ufsweeper ion transport
• Programmable temperature vaporizer injection (2 µL, split ratio 5:1)
• Rxi-5Sil MS column (30 m×0.25 mm×0.25 µm) with helium carrier at 1.2 mL/min
• Temperature programs: PTV 150–290 °C; column oven 70–280 °C gradient
• Electron ionization mode and MRM detection

Main Results and Discussion

The method resolved and quantified 126 pesticides in a single run with the following performance:

• Linearity over 10–100 ppb with R2 > 0.99 for 114 compounds
• Recoveries of 70–130% for most analytes, with 60 compounds at 90–110%
• Reproducibility (%RSD) below 10% for 115 pesticides
• LODs from 0.4 to 30 ppb and LOQs from 1 to 80 ppb
• Thermal processing at 100 °C for 10–15 minutes substantially reduced residue levels

Benefits and Practical Applications

This streamlined workflow supports high-throughput, compliant screening of pesticide residues in food safety laboratories, regulatory agencies, and quality control environments.

Future Trends and Applications

Emerging directions include:

• Automated, miniaturized sample preparation
• High-resolution mass spectrometry for non-target analysis
• AI-driven data processing for rapid residue identification
• Extension to a broader range of polar and nonpolar pesticides

Conclusion

A robust GC-MS/MS method coupled with QuEChERS extraction enables rapid, accurate detection of over 100 pesticide residues in salad matrices, demonstrating significant residue reduction through cooking.

References

• EURL-FV, 2010. Multi-residue Method using QuEChERS followed by GC-QqQ/MS/MS and LC-QqQ/MS/MS for Fruits and Vegetables.
• Shimadzu, 2013. Application Data Sheet No 71: Simultaneous analysis of Residual Pesticides in Foods via the QuEChERS Method utilizing GC-MS/MS.
• AOAC, 2007. Official Method 2007.01: Pesticide Residues in Foods by Acetonitrile Extraction and Partitioning with Magnesium Sulfate.
• Shimadzu, 2013. Application Data Sheet No 72: Scan/MRM Analysis of Residual Pesticides in Food using GC-MS/MS.