Multi-Residue Pesticide Analysis of Food Matrices using GC/MS/MS and LC/MS/MS

Importance of the Topic

The monitoring of pesticide residues in food and natural products is critical to safeguard public health and to comply with stringent regulatory limits. Multi-residue analysis enables laboratories to screen a broad spectrum of chemistries in a single run, improving surveillance efficiency and reducing turnaround times.

Objectives and Study Overview

This study presents two high-throughput screening workflows for 100 pesticides:

• A GC/MS/MS-based method using the Quattro micro triple quadrupole system for volatile and semi-volatile compounds in complex matrices.
• An LC/MS/MS approach on ACQUITY UPLC coupled to Quattro Premier for polar to moderately non-polar residues.

Both methods target sub-ppb detection, include confirmatory multiple reaction monitoring (MRM) transitions, and aim to minimize analysis time and sample preparation steps.

Methodology and Instrumentation

Sample Preparation:

• Generic extraction with organic solvents (ethyl acetate for GC, methanol/water for LC) and minimal cleanup using dispersive SPE (PSA and carbon black) or liquid-liquid partitioning.
• Matrix matched calibration standards to account for matrix effects.

GC/MS/MS Conditions:

• Column: DB-5 MS (30 m×0.25 mm×0.25 µm), PTV injection in solvent vent mode.
• Carrier gas: Helium at 1.0 mL/min; temperature ramp from 50 °C to 280 °C in 37 min.
• Acquisition: 84 MRM transitions organized in 14 time windows; dwell times adjusted for optimum S/N.

UPLC/MS/MS Conditions:

• Column: BEH C18 (2.1×100 mm, 1.7 µm); gradient from 20 % to 90 % methanol with 5 mM ammonium acetate.
• Flow rate 450 µL/min, run time <10 min, column at 40 °C.
• Ionization: ESI positive/negative switching; 26 MRM windows enabled by T-Wave collision cell technology for rapid channel switching and minimal crosstalk.

Used Instrumentation:

• Waters Quattro micro GC/MS/MS; Waters Alliance 2795 and 2695 HPLC systems.
• Waters ACQUITY UPLC coupled to Quattro Premier API MS/MS equipped with T-Wave collision cell.
• TargetLynx data management for automated quantitation and QA/QC reporting.

Key Results and Discussion

The GC/MS/MS workflow achieved limits of detection below 10 ppb for most compounds with run times under 45 minutes. Screening of spiked matrices (baby food, tea, spices, tobacco) showed >85 % detection at 10 ppb. The UPLC/MS/MS method reduced cycle time to 10–15 minutes and enhanced sensitivity through narrower peak widths (0.11 min at 5 % peak height) and higher signal intensity (5-fold increase over HPLC). Both methods allowed reliable confirmation using secondary MRM transitions.

Benefits and Practical Applications

• High throughput surveillance of up to 100 residues with generic sample prep.
• Regulatory compliance supported by sub-MRL detection limits and confirmatory capabilities.
• Integrated software tools (TargetLynx) for streamlined data processing, QA/QC flagging, and result reporting.

Future Trends and Applications

Advances in ultrahigh-performance chromatography and MS/MS hardware will continue to reduce analysis times and improve sensitivity. Emerging ion mobility separations and high-resolution MS may further expand multi-residue coverage. Integration of automated sample handling and real-time data evaluation will enhance laboratory productivity and data reliability.

Conclusion

Two complementary multi-residue workflows demonstrate robust screening and confirmation of 100 pesticides across diverse food matrices. GC/MS/MS offers comprehensive volatile analysis, while ACQUITY UPLC/MS/MS delivers rapid, sensitive quantitation for a wide range of analytes. Both approaches meet surveillance needs with high throughput, low detection limits, and integrated QA/QC solutions.

Reference

• Giles K., Pringle S., Worthington K., Bateman R. Travelling Wave Ion Propulsion in Collision Cells. ASMS Conference, 2003.
• Waters Corporation. Multi-Residue Pesticide Analysis Whitepaper, 2005.