Validation of routine polycyclic aromatic hydrocarbons analysis in waters

Significance of the topic

Polycyclic aromatic hydrocarbons (PAHs) constitute a class of persistent organic pollutants formed by fused aromatic rings, many of which are carcinogenic. Their detection at trace levels in surface water, groundwater, and wastewater is critical for environmental monitoring and public health protection. The low solubility of PAHs in water and the need for high sensitivity and throughput in routine analysis motivate the development of robust liquid chromatography methods with fluorescence detection as an alternative to more complex GC-MS protocols.

Objectives and study overview

This work describes the validation of a routine UHPLC-FLD procedure for the quantification of eleven priority PAHs in three water matrices (tap water, mineral/carbonated water, and wastewater). The method was developed to meet NF T 90-210 performance criteria under COFRAC compliance, optimizing speed, sensitivity, and resolution for levels down to 1 ng/L or higher, depending on matrix interferences.

Used instrumentation

The analytical setup comprises:

• Thermo Scientific Vanquish Flex UHPLC system (quaternary pump, split sampler, column compartment)
• Hypersil™ Green PAH column (100 × 4.6 mm, 3 µm)
• Fluorescence detector with multi-wavelength excitation/emission programming
• Chromeleon™ CDS software (version 7.2.10) with Intelligent Run Control and SmartPeaks integration tools

Sample preparation uses liquid–liquid extraction (LLE) with hexane and anhydrous sodium sulfate drying, achieving a 1,000× concentration factor prior to direct injection.

Main results and discussion

The method achieves baseline separation of 17 PAHs in 16 minutes and focuses on eleven analytes for full validation. Calibration is linear from 0.5 to 100 µg/L (R² > 0.999). Retention time stability shows RSD < 0.1%. Limits of quantification (LOQs) are 1 ng/L in tap and mineral waters, raised to 10 ng/L or 200 ng/L for selected PAHs in wastewater due to matrix interferences. Recoveries range from 81–90% in clean waters and 82–86% in wastewater. Automated re-injection driven by Chromeleon’s Intelligent Run Control enhances throughput by triggering confirmatory injections when analyte signals exceed thresholds.

Benefits and practical applications

The validated UHPLC-FLD workflow offers routine laboratories a rapid, reliable, and cost-effective tool for regulatory monitoring of PAHs in drinking and environmental waters. Direct injection simplicity eliminates the need for solid-phase extraction, reducing sample handling and turnaround time.

Future trends and opportunities

Potential developments include extension to a broader PAH panel or transformation products, coupling with mass spectrometry for added selectivity, miniaturized or on-site UHPLC systems for field analysis, and further automation of data processing and sample handling to support high-throughput monitoring programs.

Conclusion

The UHPLC-FLD method validated here meets international performance standards for eleven PAHs across diverse water matrices, combining high sensitivity, robustness, and ease of implementation. It represents a practical approach for routine environmental and quality control applications.

Reference

• U.S. Environmental Protection Agency Method 610: Polynuclear Aromatic Hydrocarbons; Cincinnati, OH, 1982.
• European Standard NF EN ISO 17993: Determination of 15 PAHs in water by HPLC-FLD after liquid–liquid extraction; 2004.
• COFRAC Technical Accreditation Guide GTA 05, Physico-chemical Analysis of Water, Rev. 02.
• NF T 90-210: Water quality — Protocol for initial method performance assessment in a laboratory; 2018.