Rapid Analysis of 303 Pesticide Residues inGreen Bean Using Triple Quadrupole GC-MS/MS

Significance of the Topic

Rapid and accurate detection of pesticide residues in food matrices is critical for ensuring consumer safety and regulatory compliance. Green bean is a common vegetable susceptible to pesticide accumulation. The increasing number of regulated compounds and stricter maximum residue limits demand methods that can screen hundreds of pesticides in a single analysis while maintaining sensitivity and reliability.

Objectives and Study Overview

This study aimed to develop and validate a single injection method for the rapid analysis of 303 GC-amenable pesticide residues in green bean using a triple quadrupole GC-MS/MS operated in timed selective reaction monitoring mode. Key performance metrics included linearity, recovery, precision, and sensitivity at low mg/kg levels.

Methodology and Workflow

Sample preparation followed a standard acetonitrile extraction and two-step solid phase extraction clean-up, followed by solvent exchange to hexane. Matrix-matched calibration standards and quality control samples at 0.010 mg/kg were prepared. The TSQ Quantum GC triple quadrupole mass spectrometer was programmed to acquire 652 SRM transitions covering 303 pesticides in a 40-minute run using timed-SRM windows tailored to individual retention times.

Used Instrumentation

• Thermo Scientific TSQ Quantum GC triple quadrupole mass spectrometer in timed-SRM mode
• TRACE GC Ultra gas chromatograph with a 5% diphenyl/95% dimethyl polysiloxane column 30 m × 0.25 mm film thickness 0.25 μm
• TriPlus liquid autosampler with hot needle injection
• Rotary evaporator for sample concentration

Results and Discussion

All 303 pesticides eluted within 40 minutes and were monitored using at least two SRM transitions each. Matrix-matched calibration curves between 0.004 and 0.040 mg/kg showed correlation coefficients above 0.99 for most compounds. Limits of detection reached as low as 0.004 mg/kg. Average recoveries at 0.010 mg/kg ranged from 73% to 110% with an average precision of 10.3% relative standard deviation. Ion ratio stability across concentration levels met confirmation requirements.

Benefits and Practical Applications

• High throughput screening of hundreds of pesticides in a single run
• Compliance with regulatory guidelines requiring two transitions per compound
• Simplified method development via tabulated SRM transition import
• Robust clean-up and sensitivity suitable for routine QA QC in food testing laboratories

Future Trends and Potential Applications

Advances in multiplexed SRM acquisition and combined GC and LC workflows may further expand the number of target analytes. Integration with automated sample preparation and data processing tools can increase throughput and reduce operator intervention. Emerging high resolution mass spectrometry could complement SRM for non targeted screening applications.

Conclusion

This application demonstrates that triple quadrupole GC-MS/MS with timed-SRM can rapidly and reliably quantify 303 pesticide residues in green bean matrix using a single analytical run. The method meets sensitivity, accuracy, and precision requirements at low mg/kg levels and offers a streamlined workflow for regulatory and industrial testing.

References

1. The Japanese Positive List System for Agricultural Chemical Residues in Foods enforcement May 29, 2006
2. GB/T 19648-2005 Method for Multi Pesticide Residues in Fruits and Vegetables by GC-MS and LC-MS-MS
3. GB/T 5009.218-2008 Determination of Multi Pesticide Residues in Fruits and Vegetables
4. European Council Directive 96/23/EC
5. AN51880 Rapid Analysis of Pesticides in Difficult Matrices Using GC-MS/MS
6. TN10239 Multi residue Pesticide Analysis in Rice by Modified QuEChERS and Ion Trap GC-MSn
7. TN10295 Multi residue Pesticide Analysis in Green Tea by Modified QuEChERS and Ion Trap GC-MSn