Hydrocarbons, C2 – C8 Analysis of hydrocarbons in urban air

Importance of the Topic

Urban air pollution, especially volatile hydrocarbons, poses health and environmental risks.

Monitoring C2–C8 hydrocarbons helps assess air quality and informs regulatory measures.

Objectives and Study Overview

This application note presents a gas chromatographic method to separate 43 C2–C8 hydrocarbons in street-level urban air collected during a winter evening rush hour in the UK.

Methodology and Instrumentation

Gas chromatography with flame ionization detection was employed using an Agilent CP-Al2O3/KCl capillary column.

• Column: 0.32 mm × 50 m, df=5 μm, PLOT Al2O3/KCl
• Temperature Program: –20 °C (3 min), ramp to 190 °C at 10 °C/min (32 min)
• Carrier Gas: Helium at 100 kPa (1.0 bar)
• Injector: Split/Splitless mode, split ratio 1:25 after 3 min
• Detector: Flame Ionization Detector (FID)
• Sample Volume: 2.0 mL; calibration range up to 740 ppb/v for ethyne

Main Results and Discussion

The optimized method achieved baseline separation of all 43 target hydrocarbons within 46 minutes.

• Efficient separation of light gases (ethane, ethylene, ethyne) and C3–C8 alkanes, alkenes, and alkynes.
• High resolution ensured clear identification of structural isomers such as 2-methylbutane vs. 2-methylpropane.
• Stable retention times and reproducible peak areas facilitated quantitative analysis.

Benefits and Practical Applications

This rapid, high-resolution method supports:

• Urban air quality monitoring and pollution source apportionment.
• Regulatory compliance testing for VOC emissions.
• Environmental research and epidemiological studies linking hydrocarbon levels to health outcomes.

Future Trends and Potential Applications

Emerging developments may include:

• Miniaturized or portable GC systems for on-site analysis.
• Coupling with mass spectrometry for enhanced sensitivity and compound identification.
• Real-time monitoring platforms using automated sampling and data processing.

Conclusion

The described GC-FID method provides a robust, reproducible, and efficient approach for comprehensive analysis of C2–C8 hydrocarbons in urban air.

Reference

B.M. Hart and C.K. Laird, National Power Technology and Environmental Centre, Surrey, UK.
Agilent Technologies Application Note A00479, published August 3, 2010.