Determination of PAH in Seafood: Optimized Sample Preparation Procedures for LC-Fluorescence Screening and GC-MS(MS) Confirmation

Importance of the Topic

Seafood consumption can be a source of exposure to polycyclic aromatic hydrocarbons (PAHs), a class of environmental contaminants known for their carcinogenic and mutagenic properties. Monitoring PAH levels in shellfish and finfish is essential for ensuring food safety, meeting regulatory standards, and protecting public health.

Objectives and Study Overview

This study presents an optimized workflow for rapid fluorescence-based screening of PAHs in seafood extracts and their confirmatory quantitation using gas chromatography–tandem mass spectrometry (GC-MS/MS). The protocol is designed to maximize extraction efficiency, minimize sample preparation time, and achieve low detection limits across various seafood matrices.

Methodology

• Sample Extraction: 15 g of homogenized tissue was processed by a dispersive QuEChERS approach using acetonitrile and buffered salts to efficiently partition PAHs into the organic phase.
• LC-Fluorescence Screening: Extract aliquots were diluted and directly injected into a large-volume flow fluorescence detector, enabling rapid PAH profiling without additional cleanup.
• SPE Cleanup for GC-MS/MS: A tandem solid-phase extraction (SPE) scheme coupled Oasis HLB and silica cartridges to remove matrix interferences and perform solvent exchange to a hexane/dichloromethane mixture.
• GC-MS/MS Confirmation: Cleaned extracts were analyzed in splitless mode with multiple reaction monitoring (MRM) transitions on a triple quadrupole mass spectrometer, targeting 16 EPA priority PAHs.

Used Instrumentation

• ACQUITY H-Class FLR system with large-volume flow cell and PAH column (4.6×50 mm, 3 µm).
• Waters Quattro Micro GC–MS/MS with Rxi-5Sil capillary column (30 m×0.25 mm×0.25 µm film) and EI+ ionization.
• DisQuE™ dispersive extraction tubes, Oasis HLB (3 cc, 60 mg) cartridges, and Sep-Pak Silica (500 mg) cartridges.

Main Results and Discussion

The QuEChERS extraction delivered recoveries above 85% for most PAHs and produced clean extracts suitable for direct LC-FL screening at low µg/g concentrations. The SPE–GC-MS/MS method achieved limits of quantitation below 50 ng/g, excellent linearity (r² > 0.995), and reproducibility (RSD < 10%) across oyster, shrimp, and finfish matrices. Matrix effects were well controlled by the tandem SPE cleanup.

Benefits and Practical Applications

• Single-extract workflow supports both high-throughput fluorescence screening and sensitive confirmatory analysis.
• Reduced solvent use and preparation time compared to traditional liquid–liquid extraction.
• Compliance with regulatory limits and improved laboratory efficiency.

Future Trends and Applications

Upcoming developments may include miniaturized QuEChERS formats, integration of high-resolution mass spectrometry for non-target screening, and full automation of extraction and cleanup steps to further increase throughput and analytical robustness in food safety laboratories.

Conclusion

The combined QuEChERS–LC-FL–SPE–GC-MS/MS protocol provides a robust, efficient, and sensitive solution for routine PAH monitoring in seafood, delivering reliable screening and confirmation with streamlined operations.

References

• Young MS, Benvenuti ME, Burgess JA, Fountain KJ. Determination of PAH in Seafood: Optimized Sample Preparation Procedures for LC-Fluorescence Screening and GC-MS(MS) Confirmation. Waters Corporation; 2011.