Determination of Polycyclic Aromatic Hydrocarbons (PAHs) and Aliphatic Hydrocarbons in Oysters by GC-MS/MS

Significance of the Topic

Oyster contamination by oil spills introduces polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons that pose health hazards to consumers. Rapid, reliable analytical methods are critical for monitoring seafood safety and tracing contamination sources.

Objectives and Overview of the Study

The study aims to develop a semi-quantitative GC-MS/MS method for simultaneous detection of 16 priority PAHs and a wide range of aliphatic hydrocarbons in oyster tissue. The method was applied to oysters spiked with Gulf of Mexico crude oil to assess performance and source characterization.

Methodology and Used Instrumentation

Sample Preparation:

• Homogenize oyster tissue and weigh 2 g aliquots.
• Fortify with isotopically labeled internal standards.
• Extract analytes using ultrasonic-assisted liquid extraction with hexane.
• Clean up extracts via silica-based SPE cartridges, followed by gentle evaporation and reconstitution in cyclohexane with injection standard.

Instrumentation:

• Thermo Scientific TRACE GC Ultra gas chromatograph.
• Thermo Scientific TSQ Quantum XLS triple quadrupole mass spectrometer.
• Ultrasonic bath, rotary evaporator, SPE manifold, Ultra-Turrax homogenizer and precision balances.

Main Results and Discussion

Method performance was demonstrated through recovery, sensitivity, and specificity evaluations:

• Aliphatic hydrocarbons (C16–C34) recoveries ranged from 52 % to 108 %; lower n-alkanes showed losses during concentration.
• High-mass PAHs recoveries (e.g. Benzo[a]pyrene, Chrysene, Benzo[b]fluoranthene, Benzo[g,h,i]perylene) ranged from 65 % to 126 %.
• Limits of detection for aliphatics: 20–100 ng/g; for high-mass PAHs: 1–7 ng/g.
• Specificity confirmed by matching retention times and characteristic ion transitions (SRM) for each target compound.
• Hydrocarbon profiles and PAH fingerprints of spiked oyster samples closely matched those of the Gulf oil reference, enabling source attribution.

Benefits and Practical Applications of the Method

The developed GC-MS/MS protocol offers:

• Rapid, simultaneous screening of aliphatic hydrocarbons and PAHs in seafood matrices.
• Semi-quantitative data suitable for safety compliance and risk assessment.
• Capability to trace oil spill sources via characteristic hydrocarbon patterns.
• Adaptability in food safety laboratories for routine monitoring.

Future Trends and Applications

Advancements may include:

• Enhanced cleanup strategies to lower detection limits for low-mass PAHs.
• Integration with high-resolution mass spectrometry for improved selectivity.
• Automation and high-throughput workflows to increase laboratory efficiency.
• Extension to other seafood species and complex environmental samples.

Conclusion

This GC-MS/MS method demonstrates reliable semi-quantitative detection of both aliphatic hydrocarbons and priority PAHs in oysters, with adequate sensitivity and specificity for oil spill assessment and food safety monitoring. The approach facilitates rapid screening and source characterization in environmental and regulatory laboratories.

Reference

Mittendorf K., Hollosi L., Ates E., Bousova K., Phillips E., Huebschmann H.-J., Chang J. Determination of Polycyclic Aromatic Hydrocarbons and Aliphatic Hydrocarbons in Oysters by GC-MS/MS. Thermo Fisher Scientific Food Safety Response Center Technical Note TG51980, 2016.