GC and GC-MS Applications for Food Safety Analysis

Importance of Topic

Food safety testing relies on highly sensitive and reliable analytical methods to detect trace levels of pesticides and contaminants in diverse food and herbal matrices. Regulatory agencies worldwide have established maximum residue limits (MRLs) often at or below 0.01 mg/kg (10 ppb), creating a demand for multi‐residue methods capable of analyzing hundreds of pesticide compounds with high throughput, low detection limits, and robust performance across complex sample types such as oyster tissue, fruits, vegetables, tea, and herbal products.

Objectives & Study Overview

• Develop generic GC‐ and GC‐MS/MS‐based workflows to analyze a broad spectrum of pesticides in food and herbal matrices.
• Compare and validate sample preparation strategies: accelerated solvent extraction (ASE), QuEChERS extraction, gel permeation chromatography (GPC), and solid‐phase extraction (SPE).
• Evaluate key instrumentation: TRACE™ GC systems, PTV injectors (splitless and simulated on‐column), GC‐ECD, single and triple quadrupole MS/MS detectors (ISQ, TSQ 8000), and autosamplers (TriPlus RSH).
• Assess analytical performance criteria—linearity, sensitivity, precision, recovery, and matrix effects—against international reference methods (EPA 8141B, EN 15662, SANCO guidelines).

Methodology & Instrumentation

• Sample Preparation
  
  • ASE: Oyster tissue spiked with organochlorine pesticides; water removal with moisture‐absorbing polymers in‐cell; hexane/acetone (1:1) extraction at 100 °C, 1500 psi.
  • QuEChERS: Cucumber and other produce; acetonitrile extraction with salts, followed by dispersive SPE cleanup (PSA, C18, GCB) and GC‐MS analysis.
  • GPC & ASE: Herbal products and teas; ASE with ethyl acetate/cyclohexane, GPC cleanup on Bio‐Beads® S-X3, solvent exchange to ethyl acetate.
  • SPE Concentration: Pyrethroid pesticides in water; HyperSep C18 cartridges, elution, reconstitution in ethyl acetate.
• Gas Chromatography
  
  • Columns: Silarylene and phenylpolysiloxane phases (TraceGOLD TG-5MS, TG-5SilMS, TG-5HT) with optional GuardGOLD pre‐columns.
  • PTV Injection: Programmable temperature vaporizer for splitless or simulated on‐column injection and inline backflush to protect columns from high‐boiling matrix residue.
  • Autosampler: TriPlus RSH liquid sampler for precise small-volume introductions and high throughput.
• Detection/Quantitation
  
  • GC‐ECD for electron‐capture detection of organochlorines.
  • Single quadrupole GC‐MS (ISQ) in SIM mode for multi‐compound screening.
  • Triple quadrupole GC‐MS/MS (TSQ 8000, Quantum XLS, TSQ 8000 Ultra) in SRM and advanced U-SRM modes for highest selectivity and sensitivity (down to 0.001 mg/kg in matrix).
  • Data Processing: Thermo Scientific XCalibur™ and TraceFinder™ for automated SRM scheduling (t-SRM), ion ratio confirmation, and quantitative reporting.

Main Results & Discussion

• ASE of organochlorine pesticides in oyster tissue yielded recoveries of 91–114% using moisture‐absorbing polymers versus 69–81% with conventional drying agents.
• QuEChERS extraction of pesticides in cucumber achieved recoveries of 75–120% RSD < 9% at 50 ng/g spike levels with TG-5MS columns and SIM‐MS detection.
• Pyrethroid assays in water at 0.1 ng/mL showed significant adsorption in amber glass vials; high‐purity clear borosilicate vials improved recoveries and linearity.
• GC‐ECD analysis of organophosphorus pesticides (EPA 8141B) on TG-5MS with deactivated quartz liners demonstrated reproducibility of 1.7–3.4% RSD for 22 compounds at 20 µg/mL.
• Multi‐residue pesticide screening in teas and herbal products via ASE/GPC cleanup and TSQ 8000 GC‐MS/MS detected over 200 analytes with LODs below 0.01 mg/kg, linearity R2 > 0.995, and QC precisions near 7.4% RSD.
• Ultra‐Selective‐SRM (U‐SRM) on TSQ Quantum XLS Ultra further improved selectivity by narrowing Q1 resolution (0.1 Da) to eliminate coeluting matrix interferences in wheat at 10 ppb levels.

Benefits & Practical Applications

• High throughput: 30‐min GC cycle times with automated backflush enable two samples per hour for hundreds of compounds.
• Robustness: Inline PTV backflush and modular injector design minimize downtime and maintenance despite heavy matrix loads.
• Sensitivity: SRM and U-SRM modes achieve sub‐ppb detection limits even in complex food and herbal matrices.
• Flexibility: Applicable to a wide range of sample types—invertebrate tissues, fruits, vegetables, teas, spices, and herbal medicines.
• Regulatory Compliance: Meets international guidelines (EPA 8141B, EN 15662, SANCO) for pesticide residue monitoring.

Future Trends & Applications

• Integration of high‐resolution time‐of‐flight MS for non‐targeted screening combined with GC‐MS/MS for confirmatory analysis.
• Miniaturized and automated sample preparation platforms (micro‐QuEChERS, on‐line ASE, robotic SPE) to further reduce solvent use and turnaround time.
• Expansion of advanced SRM scheduling and dynamic mass resolution to maximize selectivity in ever more complex food matrices.
• Application of ambient ionization techniques for rapid on‐site screening of pesticide residues in the field or at point‐of‐care.

Conclusion

A comprehensive GC and GC‐MS/MS toolbox—combining accelerated solvent extraction, QuEChERS, GPC, and SPE sample cleanup with advanced TRACE GC systems and TSQ triple quadrupole detectors—delivers high sensitivity, robustness, and throughput for multi‐residue pesticide analysis across diverse food and herbal matrices. Automated SRM scheduling, inline backflush, and rigorous data processing with TraceFinder ensure reliable compliance with stringent regulatory MRLs, while emerging technologies promise further advances in selectivity and speed.

Reference

• Method Validation and Quality Control Procedures for Pesticide Residue Analysis in Food and Feed (SANCO/12495/2011).
• Codex Alimentarius Pesticide Residues in Food and Feed Guidelines.
• EN 15662:2008 – Foods of Plant Origin: Determination of Pesticide Residues Using QuEChERS.
• EPA Method 8141B – Organophosphorus Pesticides by GC/ECD.
• Pesticide Method Reference, 2nd ed., Thermo Fisher Scientific (p/n 120390).