Resolution of Chrysene from Isobaric Interferences on Rxi®-PAH (60 m x 0.25 mm x 0.10 μm)

Importance of the Topic

Accurate determination of polycyclic aromatic hydrocarbons (PAHs) such as chrysene in complex samples is essential for environmental monitoring, food safety, and regulatory compliance. Interferences from isobaric compounds like triphenylene can compromise quantification, making robust chromatographic separation critical.

Study Objectives and Overview

This study aimed to achieve near-baseline resolution of chrysene from isobaric interferences on an Rxi®-PAH column using gas chromatography–mass spectrometry (GC–MS) with selected ion monitoring (SIM). Key goals included:

• Separating chrysene and triphenylene peaks
• Optimizing temperature programming and injection conditions
• Ensuring reliable quantification at concentrations between 0.71 and 10 µg/mL

Methodology and Used Instrumentation

A 60 m × 0.25 mm ID, 0.10 µm Rxi®-PAH capillary column was employed. Samples were introduced via a 1 µL split injection (10 : 1) at 275 °C. The oven program started at 110 °C (1.6 min), ramped to 175 °C at 30 °C/min, then to 265 °C at 1.6 °C/min, and finally to 350 °C at 4 °C/min (15 min hold). Helium served as the carrier gas at 1.0 mL/min. SIM windows were scheduled across 30 defined retention time segments, targeting diagnostic ions (e.g., m/z 226.1 for triphenylene and m/z 228.1 for chrysene).

Used Instrumentation:

• Agilent 7890B Gas Chromatograph
• Agilent 5977A Mass Selective Detector (quadrupole, EI mode)
• Premium 4 mm Precision® inlet liner with wool

Main Results and Discussion

Optimized conditions produced near-baseline separation of triphenylene (tR 49.96 min) and chrysene (tR 50.15 min). Other PAH isomers, including benzofluoranthenes and dibenzofluoranthenes, were also resolved, demonstrating the column’s selectivity. Quantitative ions provided specificity even at low microgram-per-milliliter levels, with retention time precision within ±0.05 min. This separation minimizes cross-interference and enhances analytical confidence.

Benefits and Practical Applications

• Environmental analysis: Accurate PAH profiling in soil, air, and water samples
• Food and beverage testing: Detection of trace PAHs in consumables
• Industrial QA/QC: Monitoring combustion by-products and petrochemical residues
• Regulatory compliance: Meeting stringent method requirements for PAH limits

Future Trends and Applications

Advancements in column stationary phases and fast GC techniques are expected to further reduce analysis time while maintaining resolution. Coupling with high-resolution mass spectrometry (HRMS) may enable even greater selectivity for isobaric and structural isomers. Automated method optimization software and miniaturized GC–MS platforms will expand on-site and high-throughput applications.

Conclusion

The method demonstrates reliable resolution of chrysene from challenging isobaric interferences using an Rxi®-PAH column and GC–MS SIM. Its robustness, sensitivity, and specificity make it well-suited for a variety of analytical contexts where accurate PAH quantification is critical.