PESTICIDES - Analysis by GC/LC/Sample Prep

Importance of the Topic

Pesticide residue analysis is critical for ensuring food safety and regulatory compliance. Modern analytical methods must handle diverse chemical classes at trace levels in complex matrices such as water, honey, spinach and other foods. High sensitivity, robust sample preparation and reliable chromatographic separation are essential for accurate quantitation and broad compound coverage.

Objectives and Study Overview

This collection of application studies evaluates comprehensive workflows for pesticide analysis using gas chromatography (GC), liquid chromatography (LC) and streamlined sample preparation (QuEChERS). Key goals include:

• Demonstrating improved retention and resolution of polar pesticides (glyphosate, AMPA) by HILIC and FMOC derivatization
• High-throughput screening of hundreds of pesticide residues in varied food matrices
• Comparing core-shell and fully porous LC column technologies for enhanced selectivity
• Integrating GC/MS and GC/ECD for chlorinated and organohalide pesticides

Methodology and Instrumentation

Sample Preparation:

• QuEChERS extraction (AOAC 2007.01, EN 15662) with dSPE clean-up for honey, spinach and other foods
• Underivatized HILIC and FMOC derivatization for glyphosate/AMPA analysis

Chromatography and Detection:

• LC/MS/MS with core-shell columns (Kinetex Biphenyl, EVO C18, Gemini NX-C18, Luna NH2, Synergi Fusion-RP)
• GC/MS using Zebron MultiResidue-1 and ZB-5MSi Guardian columns
• GC/ECD for chlorinated pesticides on ZB-CLPesticides columns

Instrumentation:

• AB SCIEX API 5000, 4500 QTRAP, API 3200, API 4000 tandem mass spectrometers
• Electrospray ionization in negative mode for LC/MS/MS
• Electron capture detection for selective chlorinated pesticide measurement

Main Results and Discussion

Glyphosate and AMPA:

• Underivatized HILIC on Luna NH2 achieved retention without extra steps; FMOC derivatization on Gemini C18 resolved target peaks with high sensitivity

Comprehensive Screening:

• Kinetex Biphenyl core-shell column retained polar pesticides effectively and screened 175+ compounds via LC/MS/MS
• Synergi Fusion-RP fully porous column enabled detection of >535 pesticides in under 18 minutes

Neonicotinoids in Honey:

• QuEChERS extraction combined with Kinetex Biphenyl LC/MS/MS separated eight neonicotinoids in under 10 minutes

Spinach Pesticides:

• Dual GC/MS and LC/MS/MS workflows with QuEChERS provided broad coverage of 23 compounds at 200 ng/g spike levels

GC Methods:

• Zebron MultiResidue-1 GC/MS resolved 112 pesticide analytes; ZB-CLPesticides-1/-2 GC/ECD targeted 22 chlorinated compounds

Benefits and Practical Applications

• Versatile workflows cover a wide chemical space, from polar small acids to non-polar organochlorines
• Reproducible QuEChERS sample prep reduces matrix effects and speeds processing
• Core-shell LC columns deliver sharper peaks, higher throughput and stable performance over pH 1–12
• GC/ECD provides sensitive detection of halogenated pesticides in environmental and food samples

Future Trends and Potential Applications

Emerging directions include:

• Automation of QuEChERS and online SPE coupling for higher throughput
• Ultra-high-pressure LC and sub-2 µm core-shell materials for further speed gains
• Integration of high-resolution mass spectrometry for non-target screening and suspect analysis
• Miniaturized and portable GC/MS systems for field monitoring of pesticide residues

Conclusion

The described GC, LC and QuEChERS strategies offer robust, high-throughput solutions for comprehensive pesticide residue monitoring. By leveraging advanced stationary phases and tandem MS detection, laboratories can achieve sensitive, selective and reliable quantitation across diverse food matrices.

References

• Phenomenex application notes (App IDs 22767, 22749, 22618, 20035, 22744, 20827, 20830, 16184, 22631, 22632)
• QuEChERS AOAC 2007.01 and EN 15662 sample preparation methods