PAH Analysis in Drinking Water Using Disk SPE Automated with the SPE-DEX 5000

Significance of the Topic

Polycyclic aromatic hydrocarbons (PAHs) are common environmental pollutants that pose health and regulatory challenges due to their persistence and toxicity. Accurate and efficient monitoring of PAHs in drinking water is essential to ensure compliance with standards and protect public health.

Objectives and Study Overview

This study evaluates an automated disk solid phase extraction workflow using the SPE-DEX 5000 system for determination of 16 EPA priority PAHs in drinking water. The goal is to demonstrate compliance with US EPA Method 550.1 performance criteria while improving laboratory throughput and reproducibility.

Methodology and Instrumentation

1. Sample Preparation: One liter of deionized water is acidified to pH below 2 and spiked with surrogate compounds at 5 ug L 1.
2. Extraction: Automated disk SPE with 47 mm C18 disks on the SPE-DEX 5000 system, including disk conditioning, sample loading, drying, and elution.
3. Concentration: Extracts are dried and concentrated to a final volume of 0.5 mL using a DryVap inline drying and evaporation system with DryDisk membranes.
4. Analysis: Final extracts are analyzed by HPLC on a Pinnacle II PAH column under a 60% acetonitrile/40% water gradient at 1.5 mL min 1, 40 °C, with UV detection at 220 and 254 nm.

Used Instrumentation

• SPE-DEX 5000 disk extraction system (Horizon Technology)
• 47 mm Atlantic C18 SPE disks
• DryVap inline drying and evaporation system with DryDisk membranes
• Prominence i-Series HPLC system (Shimadzu)
• Pinnacle II PAH column, 4 um, 250 mm × 4.6 mm (Restek)

Main Results and Discussion

Chromatographic separation of 16 PAHs demonstrated good resolution under optimized HPLC conditions. Nine replicate samples spiked at 5 ug L 1 were processed in batches of three, completing extraction, concentration, and analysis in under two hours. Mean recoveries ranged from 80.2% to 95.7% with relative standard deviations between 5.1% and 6.3%, satisfying the EPA 550.1 initial demonstration of capability criteria of ±30% recovery.

Benefits and Practical Applications

The automated SPE approach reduces hands-on time and solvent usage compared to manual methods while delivering reproducible recoveries that meet regulatory requirements. Laboratories can increase throughput and maintain rigorous quality control for routine drinking water analysis of PAHs.

Future Trends and Applications

Coupling automated SPE with mass spectrometric detection could further improve sensitivity and selectivity for trace-level PAHs. Advances in miniaturized disk formats and integration into online systems may enable even higher throughput for environmental and industrial QA/QC applications.

Conclusion

The automated disk SPE workflow using the SPE-DEX 5000, combined with efficient inline drying and HPLC analysis, provides a rapid, reliable, and US EPA compliant method for quantifying PAHs in drinking water. High recoveries and precision are achieved within a two-hour sample preparation and analysis cycle, supporting regulatory and research laboratories in ensuring water safety.

References

• US EPA Method 550.1 Application of Liquid Solid Extraction and High Performance Liquid Chromatography for the Determination of PAHs in Drinking Water, 1990