PAHS ANALYSIS IN PALM OIL SIGNIFICANT ROBUSTNESS IMPROVEMENTS

Significance of the Topic

Polyaromatic hydrocarbons (PAHs) pose significant carcinogenic risks even at trace levels in food products. European regulations limit PAH concentrations to 1 µg/kg in critical food matrices. Palm oil presents a challenging matrix for trace-level PAH analysis due to its complexity and high lipid content. Traditional electron ionization (EI) sources in GC/MS/MS require frequent manual cleaning, reducing laboratory throughput and consistency. The Agilent JetClean self-cleaning ion source offers continuous hydrogen cleaning, enhancing robustness and maintaining consistent performance over extended operation.

Objectives and Study Overview

The primary goal was to evaluate the precision, accuracy, linearity, and long-term robustness of an Agilent 7000C GC/MS/MS system equipped with the JetClean source for quantifying four regulated PAHs (benzo(a)pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene) in palm oil. A five-day study sequence included daily calibration curves, blank injections, quality control samples, and spiked extracts to simulate a high-throughput food-analysis environment.

Methodology

Palm oil samples were extracted directly with toluene and spiked at 5 ng/mL for each PAH, equivalent to 1 µg/kg in matrix. U-13C-labeled analogs served as internal standards. The daily injection schedule comprised blanks, a ten-point calibration series (0–100 ng/mL), QC samples at 1 ng/mL, and spiked extracts, totaling over 200 injections between calibrations.

Used Instrumentation

• Agilent 7000C triple quadrupole GC/MS/MS PAH Analyzer
• DB-EUPAH capillary column (30 m×0.25 mm, 0.25 µm) with post-column backflush
• Agilent JetClean self-cleaning ion source with continuous H2 flow

Main Results and Discussion

Daily calibration curves exhibited excellent linearity across 1–100 ng/mL, with R2 values for benzo(a)pyrene of 0.9976 (day 1) and 0.9972 (day 5). Raw area count precision for 12 injections of spiked palm oil extract yielded %RSD values below 5% for all PAHs on both days, with combined 24-injection %RSDs under 4%. Chromatographic peaks remained sharp and Gaussian throughout the study, and a statistically derived detection limit for benzo(a)pyrene reached 0.175 pg on-column. Field deployment in a routine food laboratory demonstrated uninterrupted operation over 11+ months without manual source cleaning, confirming the system’s robustness.

Benefits and Practical Applications

The JetClean GC/MS/MS configuration reliably meets and exceeds EU regulatory requirements for PAHs in food, delivering:

• Low detection limits five times below maximum legal thresholds
• Excellent precision and accuracy over extended sample series
• Reduced downtime and maintenance workload
• High laboratory productivity in QA/QC and research settings

Future Trends and Potential Applications

Advances may include integration of self-cleaning sources in high-throughput food and environmental monitoring, expansion to other complex matrices, coupling with automation and AI-driven data evaluation, and miniaturized or portable GC/MS systems. Continuous improvement of ion source technologies will support faster, greener, and more reliable trace contaminant analysis.

Conclusion

The Agilent 7000C GC/MS/MS system with JetClean self-cleaning ion source demonstrated exceptional robustness, precision, and sensitivity for PAH analysis in palm oil. It ensures regulatory compliance, minimizes maintenance, and boosts laboratory efficiency. Its prolonged stability supports demanding analytical workflows in food safety and environmental laboratories.

References

1. Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs.
2. Anderson K. A.; et al. Modified ion source triple quadrupole mass spectrometer gas chromatograph for polycyclic aromatic hydrocarbon analyses. Journal of Chromatography A 2015, 1419, 89–98.