Organochlorine Pesticides by EPA 8081A on Rtx®-CLPesticides & Rtx®-CLPesticides2

Significance of the Topic

Organochlorine pesticides remain a critical concern in environmental and food safety analysis due to their persistence, bioaccumulation potential and toxicity. Reliable quantification of these compounds at trace levels is essential for regulatory compliance, risk assessment and public health protection.

Objectives and Study Overview

This application note describes the separation and detection of 29 target organochlorine pesticides using EPA Method 8081A on two Restek GC columns (Rtx®-CLPesticides and Rtx®-CLPesticides2). The goal is to demonstrate chromatographic resolution, method sensitivity and robustness for routine pesticide screening in complex matrices.

Used Instrumentation

The study employed gas chromatography with electron capture detection (GC-ECD) configured as follows:

• Columns: Rtx®-CLPesticides, 30 m × 0.32 mm ID, 0.50 µm film thickness and Rtx®-CLPesticides2, 30 m × 0.32 mm ID, 0.25 µm film thickness.
• Injection: Direct splitless injection on drilled Uniliner (Restek cat. #20335).
• Carrier gas: Helium at constant pressure (8.7 psi; 60 kPa), equivalent to 1.3 mL/min at 120 °C.
• Oven program: 80 °C hold 1 min, ramp to 300 °C at 10 °C/min, hold 15 min.
• Detector: ECD at 300 °C.
• Sample amount: 16–160 pg on-column.

Main Results and Discussion

Chromatograms show baseline separation of 29 pesticides including dibromochloropropane, hexachlorobenzene, BHC isomers, chlordane isomers, DDT and metabolites, endosulfan isomers and other chlorinated compounds. Both columns deliver sharp peaks and consistent retention, with the thinner film column (Rtx®-CLPesticides2) providing slightly faster elution for late-eluting analytes. Dead time was approximately 1.9 minutes.

Benefits and Practical Applications

The method offers:

• High sensitivity for trace-level pesticide detection.
• Robust separation of structurally similar isomers (e.g., cis-/trans-chlordane, BHC isomers).
• Reproducible retention times suitable for routine QA/QC labs.

This approach supports regulatory monitoring of water, soil and food matrices.

Future Trends and Potential Applications

Advances may include coupling with tandem mass spectrometry for enhanced selectivity, faster temperature ramps for high-throughput screening and integration with automated sample preparation. New stationary phases with improved thermal stability or alternative inert coatings could further refine separation of challenging analytes.

Conclusion

The EPA 8081A method adapted for Rtx®-CLPesticides and Rtx®-CLPesticides2 columns provides reliable, reproducible analysis of a broad panel of organochlorine pesticides. It meets sensitivity requirements for trace monitoring and offers robust performance for routine laboratory applications.

References

1. EPA Method 8081A: Organochlorine Pesticides by Gas Chromatography.
2. Restek Corporation. Rtx®-CLPesticides and Rtx®-CLPesticides2 Application Note.