Hydrocarbons - Analysis of hydrocarbons C1-C3 and chloromethane

Importance of the topic

Volatile hydrocarbons such as methane, ethane, and propane, together with chloromethane and related C1–C3 species, play a pivotal role in petrochemical production, environmental monitoring, and fuel quality assessment. Rapid and reliable separation of these light compounds is essential for ensuring process control, regulatory compliance, and accurate research data in industrial and academic laboratories.

Objectives and Study Overview

This application note demonstrates a gas chromatographic method capable of resolving seven hydrocarbons (C1–C3) and chloromethane within a 12-minute run time. The primary goal is to showcase the performance of Agilent PoraPLOT U and PoraPLOT Q capillary columns in achieving baseline separation and quantification of target analytes at relevant concentration levels.

Methodology and Instrumentation

The analysis employs a GC-capillary technique with a dual-column configuration:

• PoraPLOT U fused-silica column, 0.53 mm × 3 m, df = 20 µm (available as 10 m under part no. CP7583)
• Connected via Quick-Seal to PoraPLOT Q fused-silica column, 0.53 mm × 25 m, df = 20 µm (part no. CP7553)

Operating conditions include an isothermal oven at 70 °C for 15 minutes, helium carrier gas at 70 kPa, split injection (1:50) at 200 °C, and flame ionization detection at 300 °C. Sample injections of 1 mL cover concentration ranges up to 1000 ppm for aliphatic hydrocarbons and 5 ppm for chloromethane and cyclopropane.

Main Results and Discussion

The method achieves clear resolution of eight target peaks in under 12 minutes: methane, ethylene, acetylene, ethane, propylene, propane, chloromethane, and cyclopropane. Baseline separation minimizes coelution risks, and the 20 µm film thickness of both columns ensures sharp peaks and reproducible retention times. Sensitivity for chloromethane at 5 ppm demonstrates suitability for trace-level monitoring.

Benefits and Practical Applications

Key advantages of this GC method include:

• Rapid throughput for routine quality control in petrochemical and energy sectors
• High resolution of light hydrocarbons and halogenated species without extensive temperature programming
• Compatibility with standard FID for cost-effective quantification

Applications extend to refinery gas analysis, environmental air monitoring, and research laboratories requiring robust screening of light volatile organics.

Future Trends and Potential Applications

Emerging directions include coupling PoraPLOT column technology with mass spectrometric detectors for enhanced compound identification and extended analyte scope. Advances in microGC and portable instrumentation may leverage this column configuration for on-site monitoring. Further development of automated sample introduction and data processing will streamline high-throughput workflows.

Conclusion

The combined PoraPLOT U and Q column setup provides an effective, fast, and reliable approach for the separation and quantification of C1–C3 hydrocarbons and chloromethane. Its simplicity, reproducibility, and robustness make it highly suitable for routine industrial and environmental applications.

Reference

Agilent Technologies. Application Note A00575: Analysis of Hydrocarbons C1–C3 and Chloromethane. Agilent Technologies, Inc.; October 31, 2011.
Dow Chemical Canada, Western Canada Division, R&D Laboratory courtesy.