Sensitive and rapid determination of polycyclic aromatic hydrocarbons in tap water

Importance of the Topic

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants with carcinogenic and mutagenic properties. Their trace-level presence in water poses risks to public health and necessitates sensitive, reliable analytical methods for regulatory compliance.

Objectives and Study Overview

This study aims to develop a rapid, sensitive HPLC method combining on-line solid-phase extraction (SPE) with UV and fluorescence detection to quantify 20 PAHs in tap water. By replacing conventional liquid–liquid extraction and off-line SPE specified in EPA Methods 550 and 550.1, the method seeks to reduce sample preparation time, labor, and solvent usage while maintaining regulatory performance.

Methodology and Instrumentation

Used Instrumentation

• Thermo Scientific™ UltiMate™ 3000 Dual Gradient Rapid Separation LC system
• Dual Gradient Pump module (DGP-3600RS)
• Rapid Separation Wellplate Sampler (WPS-3000TRS)
• Diode Array Detector (DAD-3000RS)
• Fluorescence Detector (FLD-3400RS) with programmed Ex/Em switching
• Chromeleon™ Chromatography Data System software (version 7.1 or above)

Method Parameters

• On-line SPE column: Acclaim™ PolarAdvantage II (PA2), 3 µm, 4.6×50 mm
• Analytical column: Hypersil™ Green PAH, 3 µm, 3.0×150 mm
• Mobile phase: water (A) and acetonitrile (B) gradient
• Flow rates: SPE pump 0.4–0.6 mL/min; analytical pump 0.8 mL/min
• Injection volume: 1 mL on SPE column
• Detection: UV at 254 nm for naphthalene and acenaphthylene; fluorescence for remaining PAHs with time-programmed Ex/Em wavelengths

Main Results and Discussion

Key findings

• Baseline separation of 20 PAHs achieved in 35 min
• Retention-time RSD ≤ 0.16% and peak-area RSD ≤ 1.3%, demonstrating high precision
• Calibration linearity with r2 > 0.995 across target concentration ranges
• Method detection limits (MDLs) from 0.010 to 0.72 µg/L, depending on compound and detection mode
• Recoveries in tap water spiked at 0.05 and 5 µg/L ranged from 80% to 120%
• No PAHs detected in unspiked tap water

Benefits and Practical Applications

The developed method offers

• Automated sample preconcentration, eliminating manual extraction steps
• Reduced solvent consumption and sample-preparation time
• Improved consistency and throughput for routine water analysis
• Simultaneous UV and fluorescence detection for a broad range of PAHs

Future Trends and Application Opportunities

Potential developments

• Integration with mass spectrometric detection for enhanced selectivity
• Extension to other environmental matrices such as wastewater and soil extracts
• Further miniaturization and high-throughput platforms
• Online coupling with automated sample collection systems

Conclusion

An on-line SPE HPLC method using dual UV and fluorescence detection on a Thermo Scientific UltiMate 3000 system enables rapid, sensitive quantitation of 20 PAHs in tap water. This approach reduces preparation time and solvent use while maintaining high precision, low detection limits, and compliance with regulatory methods.

Reference

• Thermo Fisher Scientific. Application Note 196: Determination of PAHs in Edible Oils by DACC-HPLC with Fluorescence Detection, 2008.
• US EPA. Method 550: PAHs in Drinking Water by LLE and HPLC with UV/Fluorescence Detection, 1990.
• US EPA. Method 550.1: PAHs in Drinking Water by LSE and HPLC with UV/Fluorescence Detection, 1990.
• US EPA. Method 610: Polynuclear Aromatic Hydrocarbons, 1982.