Extract Polynuclear Aromatic Hydrocarbons from Water, Using Solid Phase Extraction Disks

Significance of the topic

Extraction of PAHs from water is critical for environmental monitoring and regulatory compliance. SPE disk technology provides an efficient and cost-effective approach to concentrate semivolatile organic compounds from large water volumes, ensuring accurate trace-level analysis.

Objectives and overview of the study

This application note details a streamlined procedure based on US EPA Method 550.1 for isolating polynuclear aromatic hydrocarbons (PAHs) from one-liter water samples. It aims to demonstrate the use of ENVI-Disk SPE disks to achieve rapid sample processing with minimal clogging and high recovery of target analytes.

Methodology

• Sample preparation: Adjust pH below 2 using HCl, add methanol and internal standards.
• Disk conditioning: Sequentially pass through methanol and deionized water under controlled vacuum to wet the sorbent.
• Sample loading: Feed the acidified water sample onto the disk at ~100 mL/min without allowing it to dry.
• Elution: Rinse the disk with acetonitrile followed by two aliquots of dichloromethane, combining eluates.
• Cleanup: Dry the combined extract over anhydrous sodium sulfate and concentrate to a final volume of 0.5 mL for analysis.

Used Instrumentation

• 47 mm ENVI-18 DSK SPE disks (C18-modified silica).
• Vacuum filtration apparatus compatible with 47 mm disks.
• HPLC system equipped with a Vydac 201TP column (25 cm × 4.6 mm i.d., 5 μm).
• Mobile phase: water (A) and acetonitrile (B) gradient from 50% to 100% B over 12 min at 2.0 mL/min.
• Detection: UV at 254 nm and fluorescence detector for enhanced sensitivity.

Main results and discussion

The method effectively isolates 16 priority PAH compounds at low microgram-per-liter levels with clear chromatographic separation. SPE disks deliver high flow rates and minimal membrane fouling, resulting in reproducible analyte recovery and efficient sample throughput. Chromatographic parameters provided resolution of naphthalene through indeno(1,2,3-cd)pyrene.

Benefits and practical applications

• Rapid processing of large water volumes with reduced risk of clogging.
• Cost savings compared to alternative disk materials.
• Compatibility with routine QA/QC and environmental monitoring protocols.
• Adaptable to other semivolatile pollutants such as PCBs, pesticides, and phthalates.

Future trends and opportunities

Integration of SPE disk workflows with automated platforms and online coupling to mass spectrometry will further enhance sensitivity and throughput. Development of alternative sorbent chemistries and miniaturized formats may broaden applications in field-based environmental analysis and high-throughput laboratories.

Conclusion

The described SPE disk procedure aligns with EPA Method 550.1, offering a robust, efficient, and scalable approach for extracting and analyzing PAHs in aqueous matrices. Its simplicity and performance make it a valuable tool for environmental laboratories and regulatory compliance.

References

• US Environmental Protection Agency Method 550.1.