EVALUATING A ROUTINE ANALYSIS OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) FOR A NEW ELECTRON IONIZATION GC-MS/MS

Importance of the topic

Polycyclic aromatic hydrocarbons (PAHs) are persistent, toxic environmental pollutants formed by incomplete combustion of organic matter. Due to their stability and widespread occurrence, monitoring PAHs in soils, sediments, water, and food is critical for environmental and human health. Regulatory agencies worldwide set strict limits and require sensitive, selective analytical methods to ensure compliance and safety.

Study objectives and overview

This study evaluates the performance of a new electron ionization tandem mass spectrometer (Xevo TQ-GC) for routine identification and quantification of approximately 50 PAHs in sediment matrices. The aim was to assess chromatographic resolution, linearity, detection limits, and comparability to established GC-MS/MS systems.

Used methodology and instrumentation

• Sample preparation followed Environment and Climate Change Canada protocols: Soxhlet extraction of 5 g sediment with toluene, cleanup with copper and silica:alumina, concentration and reconstitution in iso-octane.
• GC conditions: Rxi-35Sil MS column (30 m × 0.25 mm × 0.25 µm), pulsed splitless injection (1 µL), inlet 310 °C, helium carrier at 1.5 mL/min, oven program 65 °C to 330 °C.
• EI-MS/MS: Xevo TQ-GC system, 70 eV, source 250 °C, transfer line 320 °C; MRM transitions optimized for target PAHs.

Main results and discussion

• Critical PAH isomers (e.g., methylchrysenes, benzo[b,j,k]fluoranthenes) were fully resolved on the Rxi-35Sil MS column, outperforming a 5-phase column.
• Calibration curves demonstrated excellent linearity (r² > 0.998) over 1–200 pg/µL, using 1/x or quadratic weighting as needed.
• Limits of detection for most PAHs were ≤1 pg/µL, matching or improving on routine requirements.
• Quantitative results for sediment samples showed strong agreement with values obtained on a different EI GC-MS/MS platform, confirming method robustness.

Benefits and practical applications

• Reliable routine workflow for comprehensive PAH monitoring in sediments meets regulatory demands.
• High sensitivity and selectivity reduce sample preparation time and re-analysis due to improved isomer separation.
• Compatibility with existing EI spectral libraries facilitates compound identification.

Future trends and potential applications

Continued development may focus on expanding the PAH panel, integrating high-resolution mass spectrometry for unknown screening, and adapting workflows to additional matrices (water, biota, food). Automation of data processing and miniaturized GC-MS features could further enhance throughput and field applicability.

Conclusion

The Xevo TQ-GC system offers robust electron ionization GC-MS/MS performance for routine analysis of a wide range of PAHs in sediments. It delivers the required chromatographic resolution, linear dynamic range, and sub-pg/µL detection limits, ensuring reliable compliance with environmental regulations.

References

• Organtini K., Crombie S., Rosnack K. (2019) Evaluating a routine analysis of polycyclic aromatic hydrocarbons for a new electron ionization GC-MS/MS. Waters Corporation.