PCBs and BFRs on Rxi®-XLB and Rxi®-17Sil MS (GCxGC)

Significance of the topic

Polychlorinated biphenyls (PCBs) and polybrominated flame retardants (PBDEs) are persistent organic pollutants of high environmental and human health concern. Their analysis demands highly selective and sensitive techniques to resolve complex mixtures and trace-level contaminants.

Objectives and Study Overview

This work demonstrates a comprehensive two-dimensional gas chromatography (GC×GC) method for simultaneous determination of PCB congeners and PBDE mixtures. The approach employs a long, nonpolar primary column paired with a short, midpolar secondary column to achieve high-resolution separation within a single analytical run.

Methodology and Instrumentation

The study used a GC×GC configuration with thermal modulation:

• Primary column: Rxi®-XLB, 30 m × 0.25 mm ID, 0.25 µm film thickness
• Secondary column: Rxi®-17Sil MS, 1 m × 0.15 mm ID, 0.15 µm film thickness
• Modulator: Thermal loop with 20 °C temperature offset, 3.5 s separation time, 1.25 s hot pulse, 0.50 s cool time
• Carrier gas: Helium, constant flow at 2.0 mL/min
• Injection: 1 µL splitless (1.0 min hold) at 250 °C with premium single taper gooseneck liner
• Detector: Micro-electron capture detector (µ-ECD) at 325 °C, data acquisition at 50 Hz
• Instrument: Agilent/HP 6890 GC with IP-deactivated guard column connection via Siltek® Press-Tight®

Main Results and Discussion

The GC×GC system provided baseline separation for all PCB congeners and PBDE components in the test mixes. Two-dimensional chromatograms revealed distinct group patterns and improved peak capacity compared to one-dimensional methods. The thermal modulation scheme enhanced detectability, particularly for late-eluting, high-molecular-weight compounds.

Benefits and Practical Applications

This methodology offers rapid, high-resolution profiling of halogenated pollutants in environmental and consumer product matrices. The combination of nonpolar and midpolar columns optimizes orthogonal separation, facilitating accurate quantitation at sub-nanogram levels. It is suitable for regulatory compliance, quality control, and research on pollutant fate.

Future Trends and Potential Applications

Advancements may include coupling GC×GC with time-of-flight or quadrupole mass spectrometry for enhanced identification and structural elucidation. Automated data processing and high-throughput sample introduction will further streamline analysis of emerging contaminants and complex environmental samples.

Conclusion

The described GC×GC–µ-ECD approach on Rxi®-XLB and Rxi®-17Sil MS columns delivers superior resolution, sensitivity, and robustness for simultaneous analysis of PCBs and PBDEs. It represents a valuable tool for environmental monitoring and industrial quality control.