Polycyclic Aromatic Hydrocarbon (PAH) evaluation in complex food matrix using Triple Quadrupole Gas Chromatography Mass Spectrometry (GC EI-MS/MS)

Significance of the Topic

This study addresses the challenge of detecting trace levels of polycyclic aromatic hydrocarbons (PAHs) in fatty food matrices. PAHs are environmental contaminants linked to carcinogenic and mutagenic risks and are strictly regulated by EU and US agencies. Effective removal of lipids and matrix interferences is essential to achieve low detection limits and reliable quantification.

Objectives and Study Overview

The poster investigates a streamlined workflow combining Enhanced Matrix Removal-Lipid (EMR-Lipid) cleanup with PSA/C18 dispersive solid-phase extraction (dSPE) and advanced GC EI-MS/MS analysis. The goal was to develop a robust method capable of quantifying EU-monitored PAHs at or below 5 ppb in complex, lipid-rich samples such as smoked salmon and palm oil.

Methodology

• Sample Preparation: Samples were spiked with target analytes and extracted using acetonitrile. EMR-Lipid sorbent selectively removed major lipid classes without affecting PAHs. A secondary dSPE cleanup combined PSA and C18 to eliminate residual interferences.
• Chromatography: Separation was achieved on a DB-EUPAH UI capillary column with a post-run backflush to purge heavy matrix components. A pulsed splitless inlet at 320 °C optimized transfer of analytes.
• Mass Spectrometry: A 7010 Triple Quadrupole MSD in EI mode monitored multiple reaction transitions (quantifier and qualifier ions) with collision energies optimized for each PAH.

Used Instrumentation

• Agilent 7890B Gas Chromatograph coupled to 7010 Triple Quadrupole Mass Spectrometer
• DB-EUPAH UI column (30 m × 0.25 mm, 0.25 µm) with EPC backflush module
• Enhanced Matrix Removal-Lipid dSPE kits and PSA/C18 EC dSPE consumables
• Self-Cleaning Ion Source and hydrogen carrier gas configuration for high-temperature operation

Main Results and Discussion

The combined EMR-Lipid and PSA/C18 cleanup achieved efficient lipid removal and minimized matrix effects, enabling reliable detection of PAHs at ≤ 5 ppb. The DB-EUPAH column provided baseline separation of isomeric compounds, while post-run backflush and self-cleaning ion source extended column and source lifetimes. The method successfully quantified EU-monitored PAHs in fatty matrices with minimal maintenance requirements.

Benefits and Practical Applications

• High throughput: streamlined cleanup reduces sample preparation time.
• Robust performance: cleaner extracts result in fewer instrument downtime events.
• Regulatory compliance: meets stringent EU and US limits for PAH analysis in foods.
• Versatility: applicable to a wide range of fatty matrices encountered in food safety testing.

Future Trends and Potential Applications

Advancements may include automation of dSPE workflows, integration with high-resolution mass spectrometry for non-targeted screening, and extension of the method to emerging PAH contaminants. Further miniaturization and on-line cleanup approaches could enhance throughput and reduce solvent consumption.

Conclusion

The optimized method combining EMR-Lipid cleanup, PSA/C18 dSPE, and GC EI-MS/MS with self-cleaning source and backflush provides a reliable, sensitive, and low-maintenance solution for PAH determination in lipid-rich food samples at regulatory levels.

References

• Anderson K.A., Szelewski M.J., Wilson G., Quimby B.D., Hoffman P.D., 2015. Modified ion source triple quadrupole mass spectrometer gas chromatograph for polycyclic aromatic hydrocarbon analyses. J. Chromatogr. A 1419, 89–98.
• PAH analysis in Salmon with Enhanced Matrix Removal. Application Note 5991-6088EN.
• Optimized PAH Analysis using the Agilent Self-Cleaning Ion Source and the Enhanced PAH Analyzer. Application Note 5991-3003EN.