Multi-Residue Pesticide Screening and Quantitation in Difficult Food Matrixes Using the Agilent 6495 Triple Quadrupole Mass Spectrometer

Significance of the topic

Food safety demands accurate multi‐residue pesticide analysis in complex matrices. Regulations such as EC 396/2005 set strict maximum residue limits (MRLs) across over 170,000 matrix‐pesticide combinations. High‐throughput, sensitive, and robust methods are essential to screen hundreds of compounds at trace levels, ensuring compliance and consumer protection.

Aims and study overview

The study develops and validates an UHPLC-MS/MS method using the Agilent 1290 Infinity UHPLC coupled to the Agilent 6495 Triple Quadrupole MS. The goal is simultaneous screening and quantitation of over 250 pesticides and metabolites in difficult matrices, exemplified by black tea, at concentrations below EU MRLs, even in highly diluted extracts.

Methodology and instrumentation

Agilent 1290 Infinity UHPLC System:

• Column: ZORBAX RRHD Eclipse Plus C18, 2.1×150 mm, 1.8 µm; 40 °C; 0.4 mL/min flow
• Mobile phase: 5 mM ammonium formate/0.1 % formic acid in water (A) and methanol (B); gradient 5–100 % B over 17 min
• Injection: 2 µL; autosampler at 6 °C

Agilent 6495 Triple Quadrupole LC/MS System with Jet Stream ESI:

• Dynamic MRM with fast polarity switching; 532 MRMs total
• Drying gas 120 °C/17 L/min; sheath gas 300 °C/12 L/min; nebulizer 30 psi
• Capillary voltage 3,500 V; detector optimized for improved ion transmission and high‐mass ions

Sample preparation:

• QuEChERS extraction of tea, fruit, and vegetables; cleanup with PSA and graphitized carbon black
• Dilutions from 1:5 to 1:100 in acetonitrile; use of solvent and matrix‐matched standards

Main results and discussion

The 6495 system’s new MS1 ion optics and detector provided up to fivefold sensitivity gains over prior models. Approximately 67 % of pesticides achieved RSD < 20 % at 1:100 dilution (0.02 ng/mL), 20 % at 1:50, and additional compounds at lower dilutions. Extensive dilution effectively mitigated matrix effects, with recoveries of 70–120 % meeting SANCO criteria. The method demonstrated robust performance over a 72-hour sequence with consistent precision.

Benefits and practical applications

• Simultaneous screening of > 250 pesticides below regulatory MRLs in a single run
• High sample dilution reduces matrix interferences, prolongs instrument uptime, and allows solvent‐based calibration
• Dynamic MRM and fast polarity switching maximize dwell times and throughput
• Applicable to various food commodities, including challenging matrices like black tea

Future trends and opportunities

Further expansion of compound libraries and use of isotope‐labeled standards could enable universal quantitation. Integration with high‐resolution mass spectrometry may support untargeted screening. Advances in AI‐driven data processing will enhance identification confidence, data mining, and laboratory efficiency.

Conclusion

The UHPLC-MS/MS method on the Agilent 1290 Infinity/6495 Triple Quadrupole platform delivers sensitive, precise, and robust multi‐residue pesticide quantitation in complex food matrices. High‐dilution strategies effectively suppress matrix effects and ensure reliable measurement below EU MRLs.

References

• Regulation (EC) No. 396/2005 on maximum residue limits of pesticides in food and feed
• SANCO/12571/2013: Method validation and quality control procedures for pesticide residue analysis
• Stahnke H. et al., Anal. Chem. 2012, 84, 1474–1482: Matrix effect reduction by sample dilution
• Parra N.P., Taylor L., Agilent Tech. Tech. Overview 5991-4089EN, 2014: Instrument Detection Limit metrics