Increased Reproducibility in the analysis of EU and EPA PAH’s with the Agilent Select PAH GC Column and Metal Microfluidic Guard Chip Technology by Gas Chromatography

Importance of the Topic

The accurate and reproducible measurement of PAHs is critical to meet stringent EU and EPA regulations and to protect food safety and environmental health. High-fat matrices, such as salmon oil, pose significant analytical challenges, leading to matrix buildup, frequent maintenance and variability in retention times and sensitivity.

Objectives and Study Overview

This study evaluates the performance of the Agilent Intuvo 9000 GC system equipped with a metal microfluidic guard chip and Agilent Select PAH GC Column versus a conventional Agilent 7890 GC. Key aims are to maintain chromatographic resolution of 25 PAH compounds, minimize maintenance downtime, ensure retention time reproducibility, improve sensitivity in high-fat samples and reduce analysis time.

Methodology and Instrumentation

Salmon oil was prepared by a 1:10 dilution in dichloromethane and further cleaned using QuEChERS EMR-Lipid to remove lipids. A suite of PAH standards (1–1000 ng/mL) was used to assess sensitivity, resolution and reproducibility. Both systems used identical temperature programs, carrier flow and Select PAH column phase, with adjustments to column dimensions and flow rate for runtime optimization.

Used Instrumentation

• Gas Chromatographs: Agilent 7890B GC and Intuvo 9000 GC
• Mass Spectrometer: Agilent 5977 MSD in SIM mode
• Columns: Select PAH GC Column 30 m×0.25 mm×0.15 μm (CP7462) and Intuvo format 15 m×0.15 mm×0.10 μm (CP7461-INT)
• Autosampler: Agilent 7693
• Inlet conditions: splitless 300 °C, split vent at 50 mL/min after 0.75 min

Results and Discussion

• Resolution: Baseline separation of 25 PAH compounds, including isomers, was achieved on both systems under identical chromatographic conditions.
• Matrix Effects and Sensitivity: After 50 injections of diluted salmon oil, the 7890 system showed significant sensitivity loss and matrix buildup, requiring liner and column trims. In contrast, the Intuvo 9000 recovered sensitivity by replacing the guard chip, with no retention time shifts.
• Maintenance Efficiency: The metal microfluidic guard chip eliminated column trimming, reducing downtime and preserving retention time reproducibility for high-fat samples.
• Runtime Reduction: Switching from a 30 m×0.25 mm column to a 15 m×0.15 mm column with reduced flow (1.2 mL/min to 0.8 mL/min) and injection volume cut runtime by 15 % without compromising resolution.

Benefits and Practical Applications

• Improved reproducibility in PAH analysis for regulatory compliance laboratories.
• Reduced front-end maintenance and downtime in high-throughput environments.
• Enhanced robustness for high-fat sample matrices using EMR-Lipid cleanup.
• Faster turnaround times with maintained chromatographic performance.

Future Trends and Potential Applications

Advancements may include further miniaturization of guard chip technology, integration of automated maintenance alerts, coupling with high-efficiency ion sources for trace-level quantitation and development of standardized sample preparation kits for complex matrices.

Conclusion

The Agilent Intuvo 9000 GC with metal microfluidic guard chip and Select PAH column delivers reliable separation of 25 PAHs in challenging, high-fat matrices. It offers consistent retention times, reduced maintenance, preserved sensitivity and shorter runtimes compared to conventional GC systems.

References

• K. Lynman. PAH Analysis with High Efficiency GC Columns: Column Selection and Best Practices. Agilent publication 5990-8572EN, 2010.
• D. Lucas, L. Zhao. PAH Analysis in Salmon with Enhanced Matrix Removal. Agilent publication 5991-6088EN, 2015.
• J. Oostdijk. Separation of 54 PAHs on an Agilent J&W Select PAH GC Column. Agilent publication SI-02232, 2010.