Ultra-High-Resolution Analysis of Polycyclic Aromatic Hydrocarbons

Significance of the topic

The accurate and efficient separation of polycyclic aromatic hydrocarbons (PAHs) is critical for environmental monitoring, pollution assessment and regulatory compliance. High-resolution UHPLC methods enable rapid, simultaneous quantitation of multiple PAH species at trace levels, supporting decision making in environmental chemistry and public health.

Objectives and Study Overview

This study evaluated ultra-high-resolution simultaneous analysis of 16 priority PAHs using a Shimadzu Nexera UHPLC system equipped with one or two Phenomenex Kinetex core-shell columns. The aim was to determine whether a dual-column configuration could achieve baseline resolution for all target compounds under a rapid gradient program.

Methodology and Instrumentation

• UHPLC system: Shimadzu Nexera with 130 MPa maximum pressure tolerance
• Columns: Phenomenex Kinetex C18 core-shell, 100 Å pore size, 100 × 4.6 mm I.D., 2.6 µm particles (single or two in series)
• Mobile phases: A = water/acetonitrile (1:1), B = acetonitrile
• Gradient: for single column, 42% B (0–1.5 min) to 85% B (3–4 min); for dual column, 42% B (0–3 min) to 85% B (6–8 min)
• Flow rate: 2.0 mL/min; column temperature: 25 °C; injection volume: 55 µL
• Detection: UV at 254 nm with semi-micro flow cell; fluorescence detection at wavelength pairs optimized for PAH groups; conventional flow cell for fluorescence

Main Results and Discussion

The dual-column setup delivered minimum resolution values above 1.5 for all 16 PAHs, compared with lower resolution for a single column. Key improvements included resolution up to 1.91 between closely eluting isomers. Fluorescence detection provided enhanced sensitivity for most compounds, with the exception of acenaphthylene. System pressure increased to around 53 MPa in the dual configuration, demonstrating the Nexera’s capability to handle high backpressure.

Benefits and Practical Applications

• Rapid baseline separation of a complex PAH mixture in under eight minutes
• High sensitivity and selectivity via dual detection modes (UV and fluorescence)
• Robust operation under elevated pressures using standard UHPLC hardware
• Applicability to environmental, food and petrochemical analysis workflows

Future Trends and Potential Applications

Advances in column technologies, such as smaller core-shell particles or novel stationary phases, may further improve resolution and speed. Coupling high-resolution UHPLC with mass spectrometry or multi-dimensional separations could enable even more comprehensive PAH profiling in complex matrices. Automation and green solvent strategies will support sustainable high-throughput analysis.

Conclusion

This application demonstrates that a dual-column UHPLC approach on the Shimadzu Nexera system achieves ultra-high resolution and sensitivity for 16 priority PAHs. The method offers rapid, reliable performance for environmental monitoring and quality control.