Rapid Screening Method for Polycyclic Aromatic Hydrocarbons Using an Advanced UHPLC Column and System

Significance of the Topic

The analysis of polycyclic aromatic hydrocarbons (PAHs) is critical for environmental monitoring and public health, as many PAHs are regulated priority pollutants due to their carcinogenic potential. Rapid and reliable screening methods enable laboratories to meet regulatory requirements efficiently and to detect trace-level contaminants in complex matrices.

Objectives and Study Overview

This application note evaluates a rapid UHPLC screening method for the EPA-targeted 16 PAHs using the Thermo Scientific Hypersil GOLD VANQUISH 1.9 µm column packed into a Vanquish UHPLC system. The study aims to demonstrate high-throughput analysis by operating at elevated flow rates and pressures, and to compare the performance of multi-linear versus non-linear elution gradients.

Methodology and Instrumentation

The UHPLC method employed three column lengths (100 mm, 150 mm, 200 mm × 2.1 mm, 1.9 µm) of Hypersil GOLD VANQUISH C18 stationary phase. A binary gradient system used water/methanol (50:50) as mobile phase A and acetonitrile as mobile phase B. Key parameters:

• Flow rate: 500 µL/min
• Column temperature: 40 °C (linear gradient), 30 °C (non-linear gradient)
• Injection volume: 1 µL
• Detection: UV at 254 nm
• Software: Chromeleon 7.2 with UHPLC method transfer tools

Samples were prepared from a certified PAH calibration mix in acetonitrile and analyzed under both multi-step linear and optimized non-linear gradient profiles.

Main Results and Discussion

The non-linear gradient improved peak distribution and enhanced resolution of the critical acenaphthene–fluorene pair without extending run time. Gradient optimization dispersed the 16 analytes evenly, achieving a full screen in 10 minutes. Increasing column length improved resolution further, with backpressures of 815 bar (100 mm), 1115 bar (150 mm) and 1370 bar (200 mm), all within the 1500 bar system limit. Resolution (Rs) values exceeded the 1.5 baseline separation threshold for all adjacent peaks on longer columns.

Benefits and Practical Applications

The combined UHPLC system and column deliver:

• Rapid 10-minute screening for all 16 EPA PAHs
• High-pressure operation up to 1500 bar for flexible column selection
• Improved sensitivity and peak shape for trace-level quantification
• Non-linear gradients to resolve critical pairs without time penalty

These attributes support environmental laboratories, QA/QC analyses, and research workflows requiring high throughput and reliable separation of hydrophobic, aromatic contaminants.

Future Trends and Potential Applications

Advances in sub-2 µm UHPLC chemistry and elevated pressure systems will continue to enable faster, more selective separations. Future directions include coupling with high-resolution mass spectrometry for confirmatory analysis, developing automated sample handling for screening large sample batches, and exploring alternative stationary phases to further enhance selectivity for isomeric PAHs.

Conclusion

This study demonstrates that the Hypersil GOLD VANQUISH 1.9 µm column paired with the Vanquish UHPLC system provides a robust, high-throughput method for screening 16 priority PAHs. Method scalability and non-linear gradient optimization yield excellent resolution in a 10-minute run, supporting regulatory compliance and routine environmental analysis.

Instrumentation Used

• Vanquish UHPLC System (Base, Binary Pump H, Split Sampler HT, Column Compartment H, Active Pre-heater, Diode Array Detector HL)
• Hypersil GOLD VANQUISH UHPLC Columns, 1.9 µm, 100/150/200 × 2.1 mm
• LightPipe™ flow cell, 10 mm
• Dionex Chromeleon 7.2 SR2 CDS

References

• United States EPA Method 610: Polycyclic Aromatic Hydrocarbons