Pesticides

Importance of the Topic

Reliable analysis of pesticide residues is critical for ensuring food safety, water quality and regulatory compliance. Gas chromatography coupled with mass spectrometry (GC-MS) remains a gold standard for multi-residue determination due to its sensitivity, selectivity and robustness. InertSearch methodology and InertCap® GC column technology enhance analyte recovery and peak integrity by minimizing active site interactions.

Study Objectives and Overview

This application note describes development and validation of a GC-MS SIM method for simultaneous detection of over 80 pesticide compounds and their analogues. Key goals include:

• Establishing chromatographic conditions to achieve baseline separation of structurally diverse pesticides.
• Demonstrating retention time reproducibility and reliable quantitation using internal standards.
• Showcasing performance of the InertCap® 5MS/NP capillary column.

Methodology and Instrumentation

Sample preparation consisted of standard solutions at 1 μg/mL in dichloromethane containing three deuterated internal standards: anthracene-d10, 9-bromoanthracene and chrysene-d12 (0.2 μg/mL each). Instrumental settings were as follows:

• System: Gas chromatograph with mass spectrometer in SIM mode.
• Column: InertCap® 5MS/NP, 30 m × 0.25 mm I.D., 0.25 µm film thickness.
• Carrier gas: Helium at a linear velocity of 40 cm/s.
• Injection: Splitless, 2 min hold at 250 °C, sample volume 2.0 μL.
• Oven program: 50 °C (3 min), ramp 10 °C/min to 200 °C, ramp 3 °C/min to 230 °C (5 min), ramp 5 °C/min to 280 °C (2 min).
• Interface and ion source temperature: 280 °C.
• Detection: Mass spectrometer in selected ion monitoring (SIM) for enhanced sensitivity.

Main Results and Discussion

The method achieved baseline separation for 83 target compounds with retention times spanning approximately 12 to 41 minutes. Representative observations include:

• Sharp, symmetrical peaks for polar and non-polar pesticides without tailing, illustrating the inert surface of the column.
• Retention time reproducibility within ±0.1 min over repeated injections.
• Sufficient sensitivity in SIM mode, allowing detection at sub-ppm levels.
• No significant carry-over or ghost peaks, supporting high throughput analysis.

Benefits and Practical Applications

This GC-MS SIM method offers several advantages for routine pesticide monitoring:

• Broad multi-residue coverage in a single run, reducing analysis time and cost.
• High inertness of column phases minimizing analyte degradation and active site adsorption.
• Easily adaptable to food, environmental water and soil testing laboratories.
• Compatibility with regulatory protocols for pesticide residue limits.

Future Trends and Potential Applications

As analytical demands evolve, this methodology can be extended and improved by:

• Integrating faster temperature programming or shorter columns for rapid screening.
• Pairing with high-resolution MS for non-target screening and confirmation of unknowns.
• Implementing automated sample preparation and data processing workflows.
• Expanding the compound panel to include new generation pesticides and metabolites.

Conclusion

The presented GC-MS SIM protocol utilizing InertCap® 5MS/NP column demonstrates robust, reproducible and sensitive analysis of a wide range of pesticides. Its performance in terms of peak shape, retention stability and detection limits makes it well suited for routine residue testing under stringent quality assurance requirements.

Reference

GL Sciences Inc. Data No. GA220-0904, InertSearch for GC™ – InertCap® Applications: Pesticides