Hydrocarbons, C6 - C9 - Reference method for monitoring systems for analysis of hydrocarbons in environmental air

Significance of the Topic

Monitoring C6–C9 hydrocarbons in environmental air is essential to assess air quality, identify sources of pollution, and ensure compliance with regulatory standards. Capillary gas chromatography coupled with flame ionization detection (GC-FID) offers a robust and sensitive approach for quantifying volatile organic compounds in ambient air samples.

Objectives and Study Overview

The aim of this application note is to demonstrate a rapid GC-FID method using an Agilent CP-Sil 5 CB column for the separation and quantification of a standard mixture of C6–C9 hydrocarbons in air samples within 12.5 minutes.

Methodology and Instrumentation

This method employs a GC-capillary system with a 0.25 mm × 25 m CP-Sil 5 CB column (0.4 µm film thickness). A temperature program starting at 35 °C with staged ramps to 120 °C ensures efficient elution. Helium serves as the carrier gas, injectors operate in split mode at 200 °C, and detection is performed by FID at 200 °C. A 10 µL sample of hydrocarbons in CS2 solvent is analyzed over a concentration range of 3–26 µg/m3.

Used Instrumentation

• GC-capillary system
• Agilent CP-Sil 5 CB column (0.25 mm × 25 m, 0.4 µm)
• Helium carrier gas
• Split injector (200 °C)
• Flame ionization detector (200 °C)

Main Results and Discussion

The optimized method achieved baseline separation of target hydrocarbons within 12.5 minutes. Key identified peaks include benzene, toluene, ethylbenzene, m/p- and o-xylene, cyclohexane, cyclohexene, and 3-methylhexane. Calibration demonstrated linear response across the specified concentration range, confirming the method’s precision and sensitivity for environmental monitoring.

Benefits and Practical Applications

• Fast analysis suitable for high-throughput air monitoring.
• Reliable quantification of C6–C9 hydrocarbons at low µg/m3 levels.
• Applicable for environmental laboratories, research, and regulatory compliance.

Future Trends and Potential Applications

Advances in automation and real-time monitoring platforms may integrate this GC-FID approach for continuous air quality assessment. Further development could extend the method to detect lower volatility organics, improve detection limits, and adapt to field-deployable systems.

Conclusion

The Agilent GC-FID method on a CP-Sil 5 CB column provides a rapid, accurate, and reproducible protocol for monitoring C6–C9 hydrocarbons in environmental air, supporting effective air quality management and regulatory adherence.