Analysis of Polycyclic Aromatic Hydrocarbons (PAH) in Palm Oil by GC-MS/MS

Significance of the Topic

Polycyclic aromatic hydrocarbons (PAHs) are recognized carcinogenic, mutagenic and teratogenic contaminants in edible oils, including palm oil. Their lipophilic nature and environmental persistence make them a major food safety concern. Regulatory agencies such as the EU have set strict limits for benzo[a]pyrene and the sum of PAH4 to protect public health, driving the need for highly sensitive, selective and robust analytical methods.

Objectives and Overview

This study establishes and evaluates a tandem solid-phase extraction (SPE) coupled with gas chromatography–tandem mass spectrometry (GC-MS/MS) MRM method on the Shimadzu GCMS-TQ8050 NX platform. The goal was to achieve qualitative and quantitative determination of 15+1 EU priority PAHs in palm oil, complying with EU Regulation limits while ensuring high throughput and reliable performance.

Used Instrumentation

• Shimadzu GCMS-TQ8050 NX triple quadrupole GC-MS/MS
• AOC-20i+s Plus autosampler
• SH-I-PAH capillary column (30 m × 0.25 mm × 0.10 µm)
• SupelMIP® SPE-PAHS (50 mg/3 mL) and Supelclean™ ENVI-Carb™ (500 mg/6 mL) SPE cartridges
• TurboVap® evaporator for sample concentration

Methodology and Instrumentation

Sample preparation involved tandem SPE extraction of 0.5 mL palm oil diluted with cyclohexane. SPE cartridges were sequentially conditioned, loaded at <0.1 mL/min, washed with cyclohexane and eluted with 5% toluene in ethyl acetate. The final extracts were concentrated to 1 mL.
GC-MS/MS analysis used splitless injection at 330 °C, helium carrier gas in constant linear velocity mode, and a temperature program rising from 110 °C to 340 °C. Each PAH was monitored with one quantifier and two qualifier MRM transitions, optimized collision energies and internal standard grouping for chrysene-D12 and perylene-D12.

Main Results and Discussion

Separation of 16 PAHs on the SH-I-PAH column delivered sharp, well-resolved peaks. Matrix-matched calibration from 0.2 to 10 µg/L showed excellent linearity (R2 ≥ 0.9979). Calculated LODs ranged from 0.038 to 0.327 µg/kg and LOQs from 0.127 to 1.090 µg/kg in oil, meeting EU criteria for PAH4 (LOD ≤ 0.30 µg/kg, LOQ ≤ 0.90 µg/kg). Recovery of PAH4 in spiked palm oil (11.17 µg/kg) fell between 76% and 88%, within the 50–120% regulatory range. Repeatability was assessed over eight replicates at low (0.5 µg/L) and mid (5 µg/L) levels, yielding RSDs < 8% and < 5% respectively. Extended precision over 72 injections at 5 µg/L exhibited RSD < 5% for most targets, demonstrating method stability and robustness.

Benefits and Practical Applications

This tandem SPE–GC-MS/MS method offers:

• High sensitivity and selectivity for trace PAH detection in complex oil matrices
• Compliance with stringent EU limits for food safety testing
• Efficient sample cleanup with minimal matrix interference
• Robust calibration and repeatability suited for routine QA/QC laboratories

Future Trends and Potential Applications

Future developments may include:

• Extension to other food matrices and environmental samples
• Automation of SPE workflows for higher throughput
• Use of alternative sorbents or micro-extraction techniques for greener sample prep
• Deployment of high-resolution MS for enhanced confirmatory analysis

Conclusion

The optimized MRM method on the Shimadzu GCMS-TQ8050 NX, combined with tandem SPE cleanup, enables reliable determination of 15+1 PAHs in palm oil at sub-µg/kg levels. Its sensitivity, linearity, precision and compliance with EU regulations make it a valuable tool for food safety and compliance laboratories.

References

• Xu T. et al., Journal of AOAC INTERNATIONAL 98(2), 529–537 (2015).
• Zacs D. et al., Food Analytical Methods 11, 2508–2517 (2018).
• EFSA Panel on Contaminants in the Food Chain, The EFSA Journal 724, 1–114 (2008).
• Commission Regulation (EU) No 835/2011.
• Commission Regulation (EU) No 836/2011.