Analysis of polynuclear aromatic hydrocarbons (PAH)

Importance of Topic

The analysis of polynuclear aromatic hydrocarbons (PAHs) is critical due to their widespread occurrence, persistence in the environment, and potential health risks. These compounds, formed during incomplete combustion of organic matter, can accumulate in air, water, soil, and food. Reliable measurement of PAH concentrations supports environmental monitoring, regulatory compliance, and risk assessment in industrial and research laboratories.

Study Objectives and Overview

This application note describes the development and validation of a gas chromatography–mass spectrometry (GC–MS) method for the resolution and quantification of 16 priority PAHs. A BPX35 capillary column is employed under a specified temperature program and splitless injection to achieve separation of analytes ranging from naphthalene to benzo(g,h,i)perylene. The target concentration for standards is 10 ng/µL in dichloromethane.

Methodology

The procedure begins with preparation of a PAH standard solution at 10 ng/µL in dichloromethane. One microliter of sample is injected in splitless mode to maximize sensitivity. The oven temperature is initially held at 100 °C for 0.5 min, ramped at 10 °C/min to 325 °C, and held for 15 min. Helium serves as the carrier gas at a constant flow of 1.0 mL/min. The injector operates at 250 °C with a 4 mm ID double taper liner. The method achieves baseline separation of all target PAHs within a single run.

Instrumentation Used

• Gas chromatograph fitted with BPX35 column (30 m × 0.25 mm × 0.25 µm, part no. 054701)
• Mass spectrometer detector for selective ion monitoring
• Helium carrier gas at 10.5 psi (1.0 mL/min)
• Splitless injection mode, 1 µL injection volume
• Oven temperature program: 100 °C (0.5 min) → 325 °C at 10 °C/min (15 min hold)

Key Results and Discussion

The method demonstrated clear resolution of 16 PAH isomers, including critical pairs such as benzo(a)anthracene/chrysene and benzo(b)fluoranthene/benzo(k)fluoranthene. Peak shapes were sharp and symmetric, and retention times were reproducible within a relative standard deviation below 1%. This performance enables accurate quantitation at trace levels and reliable identification of coeluting compounds in complex matrices.

Benefits and Practical Applications

The optimized GC–MS method offers:

• High sensitivity for trace-level PAH detection in environmental and industrial samples
• Efficient separation of structurally similar PAHs, improving data quality
• Reduced analysis time with a single temperature gradient run
• Compatibility with routine quality assurance workflows for air, water, soil, and food testing

Future Trends and Applications

Advances in fast GC, ultra-high-resolution mass spectrometry, and automated sample preparation will further enhance PAH analysis. Coupling with two-dimensional GC (GC×GC) and data-processing algorithms will improve separation of complex mixtures. Emerging portable GC–MS systems and real-time monitoring sensors will expand field applications for environmental surveillance.

Conclusion

The described BPX35 GC–MS method provides a robust, sensitive, and reproducible approach for the analysis of 16 priority PAHs. Its efficient temperature program and splitless injection enable clear analyte separation and quantitation at trace levels, making it well suited for environmental monitoring and industrial quality control.