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

Importance of the Topic

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants of concern due to their persistence, toxicity, and capacity to accumulate in seafood after oil spills. Rapid and reliable methods to detect low nanogram per gram levels of PAHs in matrices such as shrimp, oyster, salmon, and mussel support food safety monitoring, regulatory compliance, and public health assurance.

Objectives and Study Overview

This study evaluates three rapid sample preparation techniques for PAH analysis in seafood using GC/MS/MS detection. The approaches include QuEChERS extraction followed by stir bar sorptive extraction with back extraction, QuEChERS extraction with dispersive solid phase extraction cleanup, and a QuEChERS Express screening workflow utilizing a Chromatoprobe inlet for fast analysis.

Methodology and Instrumentation

• Sample matrices included shrimp, oyster, Atlantic salmon, and blue mussel tissue (ASTM SRM 1974b).
• QuEChERS extraction performed with water addition, internal standards, acetonitrile, magnesium sulfate, and sodium acetate, followed by vortex mixing and centrifugation.
• Stir bar sorptive extraction with back extraction applied to dilute QuEChERS extracts, using a polydimethylsiloxane coated magnetic stir bar and hexane for analyte recovery.
• Dispersive solid phase extraction cleanup employed magnesium sulfate, PSA, and C18 sorbents in centrifuge tubes, with direct program temperature vaporization injection of acetonitrile extracts.
• Express screening involved ethyl acetate extraction, centrifugation, manual injection of crude extract into a Chromatoprobe micro vial, and temperature programmed injection for rapid semi quantitative assessment.

Instrumentation

• Bruker 300-MS triple quadrupole mass spectrometer coupled to a 450-GC system.
• Injection ports included splitless, program temperature vaporization, and Chromatoprobe accessories.
• Chromatographic columns comprised Restek Rxi-5 Sil-MS and narrow bore DB-1 capillaries along with PDMS stir bars for SBSE.
• Automated sampling executed with a Combi-PAL autosampler.

Main Results and Discussion

• SBSE with back extraction achieved sub nanogram per gram detection limits for most PAHs, produced clean extracts, and delivered relative standard deviations below 5 percent using PTV injection.
• dSPE cleanup provided robust recovery above 10 ng/g but revealed low level contamination from sorbent packaging, indicating the need for reagent pre cleaning for lower detection limits.
• The Express screening workflow detected PAHs at concentrations above 20 ng/g in under six minutes per sample, offering rapid batch screening with manageable carryover via high temperature injector cleaning.

Benefits and Practical Applications

• High throughput analysis of up to 100 samples per day with reduced solvent consumption.
• Quantitative sub nanogram per gram detection addresses regulatory and food safety requirements following environmental incidents.
• Rapid semi quantitative screening triages samples and optimizes resource allocation for full quantitation.

Future Trends and Applications

Advancements may include automated SBSE workflows, the incorporation of isotope labeled standards for improved accuracy of late eluting PAHs, optimized dSPE sorbent handling to prevent contamination, and integration with high resolution mass spectrometry or field portable devices for on site monitoring.

Conclusion

The combination of QuEChERS based extraction and GC/MS/MS detection provides fast, sensitive, and reliable analysis of PAHs in seafood matrices. Stir bar sorptive extraction with back extraction offers superior sensitivity and extract cleanliness, dispersive solid phase extraction delivers simple cleanup for routine quantitation, and the Express screening approach supports rapid decision making. Maintaining sample preparation quality and reagent purity is essential to achieve low detection limits and accurate results.

References

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