Analysis of 126 residual pesticides in salad using triple quadrupole GCMS/MS system

Significance of the Topic

The presence of multiple pesticide residues in raw and lightly processed foods such as salad poses a direct health risk due to their consumption without thermal degradation. Rapid, reliable multi-residue analysis is essential to enforce regulatory limits, protect public health and enable high-throughput testing in food quality control laboratories.

Objectives and Study Overview

This study aimed to develop and validate a fast, sensitive and selective method for simultaneous quantification of 126 pesticide residues in pre-cooked and post-cooked salad matrices. Key goals included demonstrating linearity, reproducibility, recovery and detection limits suitable for regulatory compliance using a Shimadzu GCMS-TQ8030 system combined with the QuEChERS sample preparation protocol.

Methodology

Sample preparation followed the QuEChERS protocol: 5 g homogenized raw or heated (100 °C, 10–15 min) salad was spiked at 100 ppb, extracted with acetonitrile, partitioned with magnesium sulfate and salts, cleaned by dispersive SPE, filtered and injected into GC-MS/MS. Optimization of multiple reaction monitoring (MRM) transitions was performed using a 1 ppm standard and programmable temperature vaporization (PTV) injection.

Used Instrumentation

• GC-MS/MS system: Shimadzu GCMS-TQ8030
• Column: Rxi-5Sil MS, 30 m × 0.25 mm × 0.25 µm
• Carrier gas: Helium, linear velocity 40.2 cm/s, column flow 1.2 mL/min
• Injection: Split mode (5:1), 2 µL volume, PTV temperature program
• Mass spectrometry: Electron ionization, MRM acquisition, source at 230 °C, interface at 280 °C

Main Results and Discussion

MRM optimization enabled separation of 126 pesticides in one run with clear precursor-product ion pairs. Calibration was linear between 10 and 200 ppb (R2 ≥ 0.99 for 114 compounds; 12 slightly below). Reproducibility at 100 ppb exhibited relative standard deviations: 1–2 % for 15 compounds, 2–5 % for 75, 5–10 % for 25 and 10–20 % for 11. Recovery studies at 100 ppb showed 60 compounds within 90–110 %, 84 within 80–120 %, 113 within 70–130 % and 13 below 70 %. Limits of detection ranged from 0.4 to 30 ppb; limits of quantitation from 1 to 80 ppb, with signal-to-noise ratios well above regulatory thresholds.

Benefits and Practical Applications

• High throughput screening of raw and cooked salad samples for comprehensive pesticide profiling
• Robust quantification suitable for regulatory compliance monitoring
• Adaptable workflow for other fruits and vegetables with minimal method changes

Future Trends and Opportunities

Integration of ultra-high-resolution mass spectrometry or hybrid quadrupole-time-of-flight instruments could further improve identification of emerging or unknown pesticide metabolites. Automation of QuEChERS cleanup and direct coupling with digital data processing pipelines may accelerate routine laboratory workflows. Expanding multi-residue libraries and leveraging AI-driven spectral deconvolution can enhance screening capabilities.

Conclusion

A sensitive, selective and reproducible GC-MS/MS method was established for the simultaneous determination of 126 pesticide residues in salad, demonstrating excellent linearity, recovery and detection limits. The workflow supports rapid screening for quality control and regulatory laboratories, significantly reducing analysis time and ensuring consumer safety.

Reference

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