Quantitative Analysis of Polycyclic Aromatic Hydrocarbons in Five Edible Oil Samples by GCMS-TQ8050NX

Importance of the topic

The presence of polycyclic aromatic hydrocarbons (PAHs) in edible oils is a critical food-safety concern because these lipophilic contaminants accumulate in fatty matrices and include carcinogenic species. Regulatory limits established by the European Commission (EU 2023/915) set strict maximum levels for benzo[a]pyrene (BaP) and the sum of four marker PAHs (PAH4). Reliable trace-level analysis in complex oil matrices therefore requires selective sample cleanup and highly sensitive instrumental detection to ensure consumer safety and regulatory compliance.

Study objectives and overview

This application note describes the development and validation of a sensitive GC–MS/MS method for 14 PAHs in five commonly used edible oils (corn, olive, sesame, coconut and rice bran oil). The work combines molecularly imprinted polymer solid-phase extraction (MIP‑SPE) for selective cleanup with a Shimadzu GCMS‑TQ8050 NX triple‑quadrupole system and an automated MRM optimization workflow to expedite method development. The aim was to achieve low limits of quantification, robust recoveries across matrices and compliance with EU limits for regulated PAHs.

Methodology

Sample preparation and cleanup:

• 1 mL aliquots of each oil were spiked with an isotopically labelled internal standard (ISTD) mix. Samples were diluted with cyclohexane and processed by AFFINIMIP® SPE PAHs cartridges (MIP‑SPE).
• Cartridges were conditioned with cyclohexane, sample loaded (~0.3 mL/min), washed with cyclohexane and eluted with ethyl acetate. Eluates were evaporated under N2 below 30 °C and reconstituted in toluene for GC–MS/MS analysis.

Calibration and standards:

• Matrix‑matched calibration (derived from corn oil) with seven levels covering 0.5–100 µg/L for native PAHs. Deuterated ISTDs were used (ISTD concentration in calibration 25 µg/L).

Instrumental and data‑acquisition strategy:

• GC–MS/MS using Shimadzu GCMS‑TQ8050 NX with HTA 2800T autosampler; SH‑I‑5Sil MS column (30 m × 0.25 mm, 0.25 µm film).
• Splitless injection (1.0 µL), linear velocity flow control, oven program with rapid ramps to final high temperature to elute high‑boiling PAHs.
• MS conditions: interface and ion source temperatures optimized, solvent cut ~1.5 min, detector voltage set relative to tune result.
• Automated MRM optimization: LabSolutions “Create MS Table” and Smart Pesticides Database MRM Optimization Tool generated product‑ion scans, optimized collision energies/voltages across multiple acquisitions and compiled a final consolidated MRM method, reducing manual method‑development effort.

Used instrumentation

• Shimadzu GCMS‑TQ8050 NX triple‑quadrupole GC–MS/MS system.
• HTA 2800T autosampler (liquid, headspace, SPME capable).
• AFFINIMIP® SPE PAHs cartridges (MIP‑SPE) from Affinisep.
• Analytical column: SH‑I‑5Sil MS, 30 m × 0.25 mm, 0.25 μm film.

Main results and discussion

• Linearity and sensitivity: Matrix‑matched calibrations were linear across 0.5–100 µg/L with r2 > 0.99 for all PAHs; signal‑to‑noise ≥10 at the lowest level demonstrated adequate sensitivity for low‑µg/kg quantification in oils.
• Recoveries: Most heavier PAHs showed satisfactory recoveries. Lighter PAHs showed more variability: acenaphthylene recoveries ~60% and fluorene typically 70–85% depending on matrix. A few analytes exhibited recoveries above 120% attributed to residual matrix enhancement of the instrumental response.
• Sample results: Corn oil and rice bran oil contained no detectable levels of the 14 target PAHs. Olive oil contained chrysene at ~1 µg/kg. Coconut oil contained benz[a]anthracene (~1.1 µg/kg) and chrysene (~1.4 µg/kg). Sesame oil showed the highest contamination among samples with benzo[a]pyrene at ~1 µg/kg and PAH4 total ≈ 6 µg/kg.
• Regulatory compliance: All measured concentrations were below the EU maximum levels (BaP 2 µg/kg; PAH4 10 µg/kg for most oils, 20 µg/kg for certain fats such as coconut oil/cocoa butter), demonstrating method suitability for surveillance and compliance testing.

Benefits and practical applications

• MIP‑SPE provided selective extraction of PAHs from high‑lipid matrices, improving cleanup relative to generic sorbents and reducing matrix interferences in GC–MS/MS analysis.
• The combined workflow (MIP‑SPE + automated MRM optimization + GCMS‑TQ8050 NX) yields a robust, sensitive protocol suitable for routine quality‑control laboratories conducting regulatory monitoring of edible oils.
• Matrix‑matched calibration and isotopically labelled ISTDs improve quantitation in diverse oil matrices where matrix effects are significant.

Future trends and potential applications

• Automation and software‑assisted MRM optimization will continue to shorten method development time and improve reproducibility for complex multi‑analyte assays.
• Advances in MIP chemistries and sorbent formats (e.g., microcolumns, cartridges tailored to PAH subgroups) are likely to further enhance selectivity and recovery, especially for lighter PAHs.
• High‑resolution MS and GC×GC‑MS may be increasingly adopted for non‑target screening and improved isomer separation, complementing targeted triple‑quadrupole quantitation workflows.
• Integration of online or automated SPE and miniaturized sample handling can reduce solvent use and labor, supporting higher throughput in routine monitoring.

Conclusion

The study demonstrates a validated GC–MS/MS method leveraging MIP‑SPE for selective cleanup that achieves sensitive, linear, and generally accurate quantification of 14 PAHs across five edible oil types. The method met regulatory performance requirements and delivered practical sample‑preparation and data‑acquisition strategies suitable for routine food‑safety laboratories. Continued improvements in sorbents, automation and expanded MS capabilities will further strengthen PAH monitoring in complex food matrices.

References

1. Commission Regulation (EU) 2023/915 of 25 April 2023 on maximum levels for certain contaminants in food. Official Journal of the European Union. 2023.