Complex polycyclic aromatic hydrocarbons from coal tar on Agilent J&W Select PAH

Importance of the Topic

Coal tar contains a diverse array of polycyclic aromatic hydrocarbons (PAHs) that are environmentally and toxicologically significant. Precise profiling of these PAHs is essential for regulatory compliance, risk assessment, and quality control in industrial and environmental laboratories.

Objectives and Overview of the Study

This application note evaluates the performance of the Agilent J&W Select PAH GC column for the separation and detection of complex PAH mixtures in Standard Reference Material SRM 1597a (coal tar). The aim is to demonstrate optimized chromatographic conditions that resolve critical isomeric and high-molecular-weight PAHs in a single analytical run.

Methodology and Instrumentation

Instrument setup:

• Technique: Gas chromatography coupled to triple quadrupole mass spectrometry (GC/MS Triple Quad)
• Column: Agilent J&W Select PAH, 30 m × 0.25 mm, 0.15 µm film thickness (CP7462)
• Carrier gas: Helium, constant flow 2.0 mL/min
• Injection: 0.1 µL, splitless at 300 °C for 1 min
• Temperature program: 70 °C (0.7 min), 85 °C/min to 180 °C, 3 °C/min to 230 °C (7 min), 28 °C/min to 280 °C (10 min), 14 °C/min to 350 °C (3 min)
• Detector: Triple Quad MS with electron ionization, operated in full scan and selected ion monitoring (SIM) modes
• Sample: NIST SRM 1597a dissolved in toluene at 0.8–21 µg/mL

Main Results and Discussion

The optimized method achieved clear separation of key isomeric PAHs:

• Chrysene (66 mg/kg) from triphenylene (12 mg/kg)
• Benzo[b], [k], [j]fluoranthene isomers (37–66 mg/kg) from benzo[a]pyrene (94 mg/kg)

SIM mode enabled quantification across a wide concentration range with enhanced sensitivity. Full-scan spectra confirmed molecular ions (e.g., m/z 228 for chrysene) and characteristic fragments. A group-type analysis for MW > 302 revealed elution at the column’s maximum temperature (350 °C), although complete resolution of all high-molecular-weight isomers would benefit from extended runtime or complementary columns.

Benefits and Practical Applications of the Method

• High chromatographic selectivity for challenging PAH isomer pairs
• Single-run analysis covering low to high-molecular-weight PAHs
• Applicability for method validation using certified reference materials
• Suitability for environmental monitoring, industrial QA/QC, and regulatory compliance

Future Trends and Opportunities

Emerging needs include higher sample throughput, integration with high-resolution mass spectrometry for unambiguous identification, and development of more robust stationary phases to extend column lifetime at elevated temperatures. Advances in two-dimensional GC and sustainable column materials may further enhance PAH profiling capabilities.

Conclusion

The Agilent J&W Select PAH column, under an optimized oven program, successfully separates a broad range of PAHs in coal tar SRM 1597a within a 45 min run. While baseline resolution is achieved for many isomeric pairs, analysis of very high-molecular-weight PAHs may require longer runs or complementary techniques.

References

• Beekman M., Boersma A.H.R., Sijm D.T.H.M. (2008) Coal-tar pitch high temperature (CTPHT) under REACH. Report 601780001/2008, National Institute for Public Health and the Environment, NL.
• Bordajandi L.R. et al. (2008) Optimisation of GC-MS conditions for EU priority PAHs. J. Sep. Sci. 31, 1769–1778.
• Gómez-Ruiz J.A., Wenzl T. (2009) Evaluation of GC columns for 15+1 EU priority PAHs. Anal. Bioanal. Chem. 393, 1697–1707.
• Lerda D. (2009) Polycyclic Aromatic Hydrocarbons (PAHs) Factsheet. EC JRC Institute for Reference Materials and Measurements, JRC 500871.
• NIST (2011) SRM 1597a Complex Mixture of PAHs from Coal Tar. National Institute of Standards and Technology, Gaithersburg, MD, USA.
• Poster D.L., Schantz M.M., Sander L.C., Wise S.A. (2006) PAHs in environmental samples: critical review of GC methods. Anal. Bioanal. Chem. 386, 859–881.
• Sander L.C., Wise S.A. (1997) PAH Structure Index. NIST Special Publication, Gaithersburg, MD.
• Wenzl T., Simon R., Kleiner J., Anklam E. (2006) Analytical methods for PAHs in food and environment. Trends Anal. Chem. 25(7), 716–725.
• Ziegenhals K., Hübschmann H.J., Speer K., Jira W. (2008) Fast-GC/HRMS quantification of EU priority PAHs. J. Sep. Sci. 31, 1779–1786.