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

Significance of the Topic

The simultaneous determination of polychlorinated biphenyl mixtures (Aroclors) and brominated flame retardants (BFRs) is essential for environmental monitoring, food safety, and industrial quality control. These semi-volatile organic pollutants often co-elute in one-dimensional chromatographic systems, necessitating advanced techniques to achieve reliable separation and quantification.

Objectives and Study Overview

This application note demonstrates a comprehensive two-dimensional gas chromatography (GC×GC) method for resolving complex mixtures of Aroclors and BFRs. The study evaluates chromatographic selectivity, modulation performance, and detector response using targeted sample mixes under standardized conditions.

Used Instrumentation

Key components of the GC×GC setup include:

• Columns:
  • First dimension: Rxi®-XLB (30 m × 0.25 mm ID, 0.25 µm film thickness)
  • Second dimension: Rxi®-17Sil MS (1 m × 0.15 mm ID, 0.15 µm film thickness) with a 0.2 m deactivated guard column
• Modulation system:
  • Modulation period: 3.5 s
  • Hot pulse: 1.25 s, cold time between stages: 0.50 s, temperature offset: 20 °C
• Gas chromatograph: Agilent/HP 6890 GC
• Detector: Micro-electron capture detector (µ-ECD) at 325 °C, data rate 50 Hz
• Injection: 1.0 µL splitless (hold 1.0 min), injector temperature 250 °C, purge flow 20 mL/min
• Carrier gas: Helium at 2.0 mL/min (constant flow, corrected)
• Oven programs:
  • Rxi-XLB: 80 °C (1 min) to 120 °C at 10 °C/min, then to 300 °C at 3 °C/min
  • Rxi-17Sil MS: 85 °C (1 min) to 125 °C at 10 °C/min, then to 305 °C at 3 °C/min

Key Results and Discussion

The GC×GC configuration provided baseline separation of Aroclor congeners and BFR analytes across the two chromatographic dimensions. Modulation transferred narrow first-dimension peaks effectively into the second dimension, revealing distinct peak patterns for each compound class. The µ-ECD delivered sensitive detection of halogenated compounds with low nanogram-level limits of detection. Temperature programming on both columns optimized analyte elution windows, minimizing overlap and maximizing resolution.

Benefits and Practical Applications

• Enhanced separation power for complex mixtures enables confident identification of co-eluting contaminants.
• High sensitivity µ-ECD detection supports trace-level quantification in environmental, food, and industrial samples.
• Modularity of column selection allows customization for other semi-volatile halogenated pollutants.
• Robustness of the method suits routine QA/QC laboratories and regulatory testing.

Future Trends and Applications

Advances in fast-GCxGC hardware, novel stationary phases, and high-throughput detectors will further reduce analysis time while improving resolution. Integration with mass spectrometry will enable accurate mass assignments and automated library matching. Emerging software for automated peak deconvolution and chemometric analysis will streamline data processing for complex environmental matrices.

Conclusion

The described GC×GC method using Rxi®-XLB and Rxi®-17Sil MS columns, coupled with μ-ECD detection, offers a powerful tool for simultaneous analysis of Aroclor PCBs and brominated flame retardants. It achieves high selectivity, sensitivity, and reproducibility, meeting the demands of modern analytical laboratories.

References

No references were provided in the source document.