PAH Analysis in Fatty and Complex Matrix using GC/MS/MS - Pumpkin Seed Oil

Significance of the Topic

Polycyclic aromatic hydrocarbons (PAHs) are toxic contaminants regulated by the European Commission due to their carcinogenic potential.
Fatty matrices such as pumpkin seed oil pose analytical challenges because lipids can interfere with detection and instrument performance.
Developing a reliable, sensitive workflow is essential for ensuring food safety and regulatory compliance.

Study Objectives and Overview

This study aimed to evaluate a combined sample‐preparation and GC/MS/MS approach for the determination of the 16 EU priority PAHs in pumpkin seed oil.
The method leverages enhanced lipid removal technology and advanced mass spectrometric techniques to meet the limits set by Commission Regulation No. 1881/2006 (2 µg/kg for benzo[a]pyrene and 10 µg/kg for the sum of four PAHs in edible oils).

Methodology and Instrumentation

Sample Preparation:

• Extraction with acetonitrile followed by cleanup using BondElut EMR-Lipid to trap triglycerides and other lipids.
• Post‐cleanup refinement via EMR-Polish and PSA/C18 dispersive SPE to remove residual interferences.

GC/MS/MS Configuration:

• Agilent 7890 gas chromatograph equipped with splitless inlet (320 °C) and a 30 m × 0.25 mm PAH-selective column.
• Backflush capability to purge high boilers and extend column life.
• Agilent 7010 triple quadrupole mass spectrometer with JetClean self-cleaning ion source and retention time locking for consistent peak alignment.
• Oven program: initial 80 °C, ramps to 325 °C with hold; helium carrier gas at 1.2–1.5 mL/min.

Mass Spectrometry:

• Electron ionization at 70 eV, collision energy 50 eV for fragmentation of parent ions [M]+ to product ions [M]+ and [M-2]+.
• High-efficiency source at 300 °C, quadrupoles at 150 °C, transfer line at 320 °C.

Main Results and Discussion

Recovery and Precision:

• Recoveries for early and mid‐eluting PAHs ranged from 60 % to 120 %, meeting typical validation criteria.
• Relative standard deviations were below 20 % at spiking levels of 1, 10 and 50 ppb.

Linearity and Accuracy:

• Calibration curves over 1–100 ppb yielded R2 values above 0.99 for all 16 analytes.
• Accuracy tests demonstrated consistent quantification within ±20 % across the concentration range.

Instrument Performance:

• Backflush reduced carryover and shortened cycle time by removing high-boiler residues.
• JetClean minimized source fouling, extending maintenance intervals.
• Retention time locking maintained chromatographic reproducibility over multiple runs.

Benefits and Practical Applications

The combined EMR-Lipid cleanup and GC/MS/MS workflow offers:

• Effective lipid removal, reducing matrix effects and enhancing sensitivity.
• Robust instrument operation with fewer source cleanings and extended column life.
• Compliance with EU regulatory limits in routine food safety testing laboratories.

Future Trends and Opportunities

Expanding this approach to other fatty or complex matrices such as nut oils, dairy products or smoked foods.
Incorporating high-resolution mass spectrometry for non‐target screening of emerging contaminants.
Automation of sample preparation and data processing to increase throughput and reproducibility.
Exploring green solvents and sorbents to reduce environmental impact.

Conclusion

The validated method combining EMR-Lipid cleanup, PSA/C18 dSPE and GC/MS/MS with backflush, JetClean and retention time locking provides a sensitive and reliable platform for monitoring EU priority PAHs in pumpkin seed oil.
This streamlined protocol ensures regulatory compliance, operational efficiency and high data quality for food safety laboratories.

Used Instrumentation

• Agilent 7890 Gas Chromatograph with splitless inlet, backflush and retention time locking.
• Agilent 7010 Triple Quadrupole Mass Spectrometer with JetClean self-cleaning ion source.
• BondElut EMR-Lipid and EMR-Polish sorbents, PSA/C18 dispersive SPE kits.

Reference

• Agilent Technologies, Application Note 5991-3003EN.
• Stamatelopoulos A., et al., Journal of Chromatography A, 1419 (2015) 89–98.