NEW Rxi®-PAH GC Column

New Rxi-PAH GC Column for PAH Analysis

Importance of the Topic

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants and food safety hazards due to their mutagenic and carcinogenic properties. Accurate separation and quantification of isobaric PAHs, especially the EFSA priority PAH4 group, are essential for regulatory compliance, public health protection, and environmental monitoring.

Objectives and Study Overview

This work evaluates the performance of Restek’s new Rxi®-PAH gas chromatographic column for resolving challenging isobaric PAHs, including the EFSA PAH4 set (benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[a]pyrene). The study demonstrates selectivity improvements over conventional GC columns and examines ruggedness for routine food safety and environmental analyses.

Methodology and Instrumentation

The stationary phase features elevated phenyl content with arylene modification and surface bonding, enhancing thermal stability and selectivity. A 40 m × 0.18 mm ID, 0.07 µm Rxi-PAH column was assessed under the following conditions:

• Injection: 0.5 µL pulsed splitless (0.58 min hold), Restek Premium 2 mm single‐taper wool liner
• Oven program: 110 °C (1 min) to 210 °C at 37 °C/min, to 260 °C at 3 °C/min, to 350 °C at 11 °C/min (4.5 min hold)
• Carrier gas: He constant flow, 1.4 mL/min
• Detector: Quadrupole MS in SIM mode (transfer line 350 °C, source 350 °C, quad 200 °C), PFTBA tune, EI ionization

Key Results and Discussion

Baseline separation of all EFSA PAH4 compounds was achieved in under 33 min. Chrysene was fully resolved from triphenylene and cyclopenta[cd]pyrene, and all benzo[b], [k], [j], and [a] fluoranthene isomers were individually eluted. The column demonstrated thermal stability up to 360 °C, enabling routine analysis of high-molecular-weight, low-volatility dibenzo pyrenes without bleed interference. High column efficiency allowed multiple trims without loss of critical separations.

Advantages and Practical Applications

The Rxi-PAH phase provides:

• Superior selectivity for regulatory PAHs that cannot be resolved by standard columns
• Rugged performance for high-throughput QA/QC and environmental protocols
• Flexible configurations: narrow bore (0.18 mm) for rapid analysis, wider bore (0.25 mm) for greater sample capacity and maximum resolution
• No compromise in resolution after repeated column trimming

Future Trends and Applications

Emerging directions include coupling high-selectivity phases with high-resolution MS for trace-level quantification, development of faster GC temperature programming, micro-GC formats for field analysis, and expansion of regulated PAH panels to include alkylated and heterocyclic derivatives. Integration with automated sample preparation and data-processing workflows will further streamline routine monitoring.

Conclusion

Restek’s Rxi-PAH GC column delivers exceptional separation of critical PAHs, meeting stringent food safety and environmental method requirements. Its combination of unique selectivity, thermal stability, and robustness makes it a valuable tool for laboratories demanding reliable and efficient PAH analysis.

References

• NIST SRM 2260a PAH Mix, diluted in toluene for performance evaluation
• Restek Application Note GNTS1718-UNV on Rxi-PAH column performance