Analysis of Chlorinated Pesticides by GC/MS

Significance of the Topic

The accurate quantification and confirmation of chlorinated pesticides in environmental and industrial wastewater is essential for regulatory compliance and public health protection. Analytical methods defined by the US Environmental Protection Agency, such as methods 608, 617 and 8080, require reliable separation and identification of trace organochlorine compounds to monitor discharges under 40 CFR 136.1.

Study Objectives and Overview

This study aimed to evaluate the suitability and performance of the Thermo Scientific TraceGOLD TG-5SilMS GC column for confirmational analysis of organochlorine pesticides in accordance with US EPA methods 608, 617 and 8080. A representative mixture of pesticides and PCBs at 1 ng/µL was analyzed to demonstrate retention, peak shape, and identification parameters.

Methodology

Sample Preparation

• A standard mix of organochlorine pesticides was prepared at 1 ng/µL in solvent.
• 1 µL of this solution was injected in splitless mode.

Chromatographic Conditions

• Column: TraceGOLD TG-5SilMS, 30 m × 0.25 mm × 0.25 µm with 2 m guard column.
• Oven Program: 60 °C (5 min hold), ramp at 8 °C/min to 300 °C, final hold 10 min.
• Carrier Gas: Helium at 1.5 mL/min (constant flow).
• Injector Temperature: 275 °C, splitless for 1 min, split flow 30 mL/min.

Mass Spectrometry

• Instrument: Ion trap MS in EI+ mode, 45–450 amu segmented scan.
• Source Temperature: 225 °C; Electron Energy: 70 eV.
• Segmented mode to optimize ion statistics for each compound group.

Instrumentation Used

• Thermo Scientific TRACE GC Ultra with TriPlus Autosampler.
• Thermo Scientific ITD 230 LT Ion Trap MS with 250 L/s turbomolecular pump.
• TraceGOLD TG-5SilMS analytical column and appropriate guard column and connectors.
• Consumables: septa, liners, syringes, ferrules as per standard GC/MS practice.

Key Results and Discussion

The TG-5SilMS column provided baseline separation and sharp peaks for a range of organochlorine pesticides, meeting retention and identification criteria of EPA methods 608, 617 and 8080. Minimal peak tailing indicated low active site interaction. A total ion chromatogram demonstrated clear resolution of over 30 target analytes, including HCH isomers, DDT derivatives, endosulfans, and PCBs. Retention time reproducibility and ion ratio precision supported reliable confirmational analysis.

Benefits and Practical Applications

• Improved peak shape and resolution enhance confidence in identification and quantification.
• Compliance with EPA methods ensures regulatory acceptance for environmental laboratories.
• Versatility of the TG-5SilMS phase accommodates a wide range of chlorinated pollutants.

Future Trends and Potential Applications

Advances in high-resolution mass spectrometry may further improve detection limits and confirmational specificity for trace contaminants. Automation of sample preparation and coupling with multi-dimensional GC could expand throughput and compound coverage. The TG-5SilMS column may be applied to emerging halogenated pollutants and complex environmental matrices.

Conclusion

The Thermo Scientific TraceGOLD TG-5SilMS column demonstrated excellent performance for confirmational GC/MS analysis of chlorinated pesticides under US EPA methods 608, 617 and 8080. The method delivered robust separation, reliable identification, and suitability for routine environmental monitoring.

References

1. US EPA Method 608
2. US EPA Method 617
3. US EPA Method 8080