Evaluation of Rapid Extraction and Analysis Techniques for Polycyclic Aromatic Hydrocarbons (PAHs) in Seafood by GC/MS/MS

Importance of the Topic

The analysis of polycyclic aromatic hydrocarbons (PAHs) in seafood has become critically important for assessing marine pollution and ensuring food safety. Following environmental incidents such as oil spills, rapid and reliable methods are required to monitor PAH contamination in fish and shellfish. Improvements in sample preparation and instrumental detection directly impact laboratory throughput, cost, and the ability to protect public health.

Objectives and Overview of the Study

This study compared three fast sample preparation techniques combined with tandem gas chromatography-mass spectrometry (GC/MS/MS) to determine the most effective workflow for PAH quantitation and screening in seafood matrices. The goals were to optimize cleanup, minimize matrix interference, achieve low detection limits, and enable high sample throughput.

Methodology and Instrumentation

Three distinct sample preparation approaches were evaluated:

• QuEChERS extraction followed by stir bar sorptive extraction (SBSE) and back-extraction (TBE)
• QuEChERS extraction with dispersive solid phase extraction (dSPE) cleanup
• QuEChERS “Express” extraction with rapid screening via a Chromatoprobe™ inlet

Key steps in each workflow included salt-based partitioning, sorptive enrichment or cleanup, and direct or PTV injection into the GC/MS/MS system. Calibration and validation used matrix spikes in shrimp, oyster, salmon, and blue mussel reference material.

The main instrumentation comprised:

• Bruker 300-MS triple quadrupole mass spectrometer coupled to a 450-GC system
• Combi-PAL autosampler with split/splitless and PTV inlets, plus a Chromatoprobe inlet accessory
• Restek Rxi-5 Sil-MS and narrow bore DB-1 columns for analyte separation
• SBSE devices coated with PDMS for enrichment and Restek Q-sep dSPE reagent packs for cleanup

Main Results and Discussion

• The QuEChERS-SBSE-TBE method delivered very clean extracts with minimal co-extracted matrix and achieved quantitation down to sub-1 ng/g levels when combined with PTV injection.
• QuEChERS-dSPE cleanup provided similarly low detection limits and good recoveries for most PAHs, although low-level contamination from reagent packaging was identified and can be mitigated by solvent rinsing or repackaging.
• The Chromatoprobe screening approach enabled rapid detection of PAHs at 20–50 ng/g in under six minutes, suitable for batch screening but not detailed quantitation.
• Matrix interference was effectively controlled by tandem MS transitions and robust cleanup. Method precision and accuracy were validated using matrix spikes and SRM 1974b mussel tissue.

Benefits and Practical Applications

• High throughput: over 50–100 samples per day with minimal solvent use and no lengthy solvent exchanges.
• Flexibility: sub-ng/g quantitation methods for regulatory and research purposes, and rapid screening for preliminary assessments.
• Cleaner extracts: SBSE yields color-free back-extracts, reducing instrument maintenance and carryover.
• Enhanced sensitivity: PTV injection optimizes acetonitrile-based extracts and early-eluting analytes.

Future Trends and Opportunities

• Further optimization of SBSE coating and extraction conditions to improve recoveries of late-eluting PAHs.
• Development of fully automated workflows integrating QuEChERS, SBSE, and thermal desorption devices.
• Adoption of isotopically labeled standards to correct for matrix effects at ultra-trace levels.
• Exploration of mini-aturized and ambient ionization techniques for even faster screening.
• Improved packaging and pre-conditioning of dSPE reagents to eliminate background contamination.

Conclusion

The combination of QuEChERS-based sample preparation with GC/MS/MS provides a powerful platform for rapid, sensitive, and accurate analysis of PAHs in seafood. Both SBSE and dSPE cleanup approaches achieve sub-ng/g quantitation, while the Chromatoprobe offers a fast screening alternative for higher concentration ranges. Ongoing refinements in sorptive extraction, injection techniques, and reagent handling will further enhance method robustness and throughput.

References

• Noaa Technical Memorandum NMFS-NWFSC-59. Sloan CA, Brown DW, Pearce RW, et al. Extraction, Cleanup, and GC/MS Analysis of Sediments and Tissues for Organic Contaminants. NOAA, March 2004.
• Anastassiades M, Lehotay SJ, Stajnbaher D, Schenck FJ. Fast and Easy Multiresidue Method (QuEChERS) for Pesticide Residues. J AOAC Int. 2003;86:412.
• Mastovski K, et al. Collaborative Study on PAHs in Seafood by GC-MS. Covance Laboratories Inc.
• Cochran J. QuEChERS with GC-TOFMS and GC×GC-TOFMS for PAHs in Oil-Contaminated Seafood. Florida Pesticide Residue Workshop, 2010.
• Pfannkoch EA, Stuff JR, Moran JH, Whitecavage JA. High-Throughput PAH Determination in Seafood by QuEChERS-SBSE-GC-MS(E). GERSTEL Inc.
• Hauser B, Popp P, Bauer C. Semi-Automated SBSE-HPLC-Fluorescence for PAHs in Water. UZE Leipzig-Halle, Germany.