Hydrocarbons, C1 – C4

Significance of the Topic

Understanding and quantifying C1–C4 hydrocarbons is crucial in energy production, environmental monitoring and industrial process control. Their accurate measurement ensures process safety, product quality and regulatory compliance.

Objectives and Study Overview

This study evaluates a capillary gas chromatography method using an Agilent CP-Silica PLOT column for separating and identifying light hydrocarbons (C1 to C4). It aims to demonstrate stable retention times under potential polar interferents and to contrast isomer selectivity against an Al2O3 PLOT column.

Methodology

A gas chromatograph equipped with a capillary injector and FID was operated isothermally at 60 °C. Helium at 150 kPa served as carrier gas. Samples of 1% hydrocarbon mixtures in nitrogen were introduced via split injection (250 °C). Separation was achieved on a 0.32 mm×30 m, 4 µm CP-Silica PLOT column, with detection at 250 °C.

Instrumentation Used

Agilent GC-capillary system with:

• CP-Silica PLOT column (0.32 mm×30 m, 4 µm df, Part no. CP8567)
• Split injector (250 °C)
• Flame ionization detector (250 °C)
• Helium carrier gas

Main Results and Discussion

Fifteen hydrocarbons—including methane, ethane, ethylene, acetylene, propane, cyclopropane, propylene, various C4 isomers and dienes—were baseline resolved. Retention times remained constant despite the presence of typical polar contaminants (water, sulfur species, CO2). The Al2O3 PLOT column showed higher selectivity for C4 isomer separation but the CP-Silica PLOT provided robust, interference-resistant performance.

Benefits and Practical Applications

The method offers reliable quantitation of light hydrocarbons in natural gas, refinery streams and process gases. Its insensitivity to moisture and other polar impurities reduces sample pretreatment, streamlining QA/QC workflows and environmental analyses.

Future Trends and Opportunities

Advancements may include coupling with mass spectrometry for trace-level detection, rapid micro-column GC systems for on-site monitoring, and novel stationary phases to further enhance isomer discrimination. Integration into automated platforms can support real-time process analytics.

Conclusion

The Agilent CP-Silica PLOT column enables fast, interference-resistant separation of C1–C4 hydrocarbons, ensuring accurate identification and quantitation. For enhanced isomer resolution, the Al2O3 PLOT column remains a complementary option, providing analysts with flexible tools for comprehensive hydrocarbon profiling.