Polynuclear Aromatic Hydrocarbons US EPA Method 610 - Rxi™-5ms

Significance of the Topic

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants formed during incomplete combustion of organic matter. Due to their persistence, toxicity, and regulatory importance, reliable quantitative analysis is essential for environmental monitoring, food safety, and industrial quality control.

Objectives and Study Overview

This work demonstrates US EPA Method 610 for simultaneous determination of 28 priority PAHs. A calibration strategy incorporates surrogate and internal standards to ensure accurate quantification. The target analytes include simpler two-ring compounds (e.g., naphthalene), intermediate compounds (e.g., phenanthrene, fluoranthene), and high-molecular-weight species (e.g., benzo(a)pyrene, dibenzo(a,h)anthracene).

Methodology and Instrumentation

The analysis employs gas chromatography–mass spectrometry with electron impact ionization. Key parameters:

• Column: Rxi™-5ms, 30 m × 0.25 mm ID, 0.25 µm film
• Carrier gas: helium at 1.2 mL/min constant flow
• Injection: 1 µL splitless (0.1 min), inlet at 275 °C with 4 mm drilled liner
• Oven program: 75 °C (0.5 min), ramp to 245 °C @ 25 °C/min, then to 330 °C @ 4 °C/min (1 min hold)
• Mass spectrometer: Agilent 5973 GC/MS, transfer line 280 °C, scan range 35–550 amu, solvent delay 2 min, tune DFTPP, EI mode

Main Results and Discussion

The method achieved baseline separation of all 28 PAHs within a total runtime of approximately 20 minutes. Retention times span from under 5 minutes for low-molecular-weight compounds to about 16 minutes for high-molecular-weight species such as benzo(b)fluoranthene and benzo(k)fluoranthene. Precision for retention times and peak areas met EPA criteria, and the use of deuterated surrogates corrected for matrix effects.

Benefits and Practical Applications

This protocol offers high sensitivity (10 ng injection) and robustness suitable for regulatory compliance, environmental surveys, food and water testing, and industrial QA/QC. The inclusion of surrogate and internal standards enhances accuracy and traceability.

Future Trends and Potential Applications

Advances may include coupling with high-resolution mass spectrometry for improved selectivity, fast GC techniques to reduce run times, and automated sample preparation for higher throughput. Emerging ambient ionization methods and miniaturized instrumentation could enable real-time field analysis of PAHs.

Conclusion

The described GC-MS method based on EPA 610 provides a validated, reproducible approach for comprehensive PAH profiling. Its sensitivity, accuracy, and adherence to regulatory guidelines make it a valuable tool for diverse analytical laboratories.