Improved Determination of Polychlorinated Biphenyl Compounds by US EPA Method 1628

Importance of the Topic

Polychlorinated biphenyls (PCBs) are persistent organic pollutants banned decades ago yet remain environmental hazards due to their chemical stability and tendency to bioaccumulate. Reliable determination of PCB congeners in environmental matrices is critical for regulatory compliance, risk assessment, and safeguarding public health. US EPA Method 1628 provides a framework for low-resolution GC/MS analysis; however, traditional helium-based approaches often entail lengthy run times and incomplete resolution of co-eluting congeners.

Study Objectives and Overview

This study presents an optimized workflow for the analysis of 65 PCB congeners targeted by EPA 1628. Key goals included:

• Reducing analysis time while preserving or improving chromatographic resolution.
• Meeting EPA calibration and sensitivity benchmarks.
• Demonstrating performance in selective ion monitoring (SIM) mode using hydrogen as a carrier gas.

Methodology and Instrumentation

The analysis employed the following configuration:

• Agilent 8890 GC coupled with a 5977C MSD featuring a HydroInert ion source.
• DB-XLB capillary column (20 m × 180 µm ID × 0.18 µm film).
• Hydrogen carrier gas at 0.9 mL/min column flow.
• Injection volume: 1 µL; inlet temperature: 310 °C.
• Oven program: 50 °C (0.4 min), 30 °C/min to 180 °C, then 10 °C/min to 300 °C (1.257 min hold).
• Transfer line at 300 °C; ion source at 280 °C.
• SIM mode targeting diagnostic ions for each congener.

Main Results and Discussion

This optimized method achieved baseline separation of the 65 calibrated congeners in just over 15 minutes. Highlights included:

• Resolution of critical co-eluting pairs such as PCBs 28/31 and congeners 41/64, 85/120, and 139/149.
• Six-point calibration (10–2000 ppb) with r² > 0.97 and average response factors below 20 across all targets.
• Signal-to-noise ≥ 3:1 at 10 ppb for PCB 118, satisfying EPA sensitivity criteria.

Benefits and Practical Applications

• Over 50% reduction in run time compared to helium-based protocols, enhancing laboratory throughput.
• Improved selectivity via the DB-XLB column and SIM detection facilitates analysis of complex samples.
• Hydrogen carrier gas offers cost savings and sustainability advantages over helium.
• Full compliance with EPA Method 1628 ensures data acceptability for environmental monitoring.

Future Trends and Potential Applications

• Integration with automated sampling and data processing workflows for high-throughput environmental screening.
• Extension of hydrogen-based GC/MS methods to other classes of persistent organic pollutants.
• Development of novel stationary phases to target emerging PCB metabolites and degradation products.
• Application of multidimensional GC approaches to achieve sub-ppb detection in challenging matrices.

Conclusion

The synergy of hydrogen carrier gas, the DB-XLB column, and the Agilent 8890/5977C GC/MSD with HydroInert ion source delivers rapid, robust, and sensitive analysis of 65 PCB congeners under EPA Method 1628. This optimized workflow is well suited to environmental and regulatory laboratories seeking to improve efficiency and data quality.

References

• US EPA. Method 1628: Polychlorinated Biphenyl (PCB) Congeners in Water, Soil, Sediment, Biosolids, and Tissue by Low-resolution GC/MS using Selected Ion Monitoring. July 2021.
• US EPA. Toxic Substances Control Act (TSCA) of 1979.