Halogenated hydrocarbons - Analysis of dibromomethane in methane

Significance of the Topic

The accurate measurement of trace levels of halogenated hydrocarbons such as dibromomethane in methane is critical for applications in environmental monitoring, gas quality control, and industrial process safety. Rapid and reliable analysis helps ensure regulatory compliance and prevents contamination in high-purity gas streams.

Objectives and Study Overview

This application note demonstrates a fast micro-gas chromatography (micro-GC) method for separating and quantifying dibromomethane (CH2Br2) in a methane matrix. The goal is to achieve baseline separation within four minutes, enabling high-throughput screening of methane samples with minimal sample preparation.

Methodology and Instrumentation

• Technique: Micro-gas chromatography without pressure programming
• Column: Agilent PoraPLOT Q fused silica PLOT column (0.32 mm x 10 m, 10 µm film thickness)
• Temperature: Isothermal at 160 °C
• Carrier Gas: Helium at 200 kPa (2 bar, 28 psi)
• Injector: Unheated, injection time 255 ms
• Analyte Concentration Range: High levels (demonstration at 50 ppm)
• Instrumentation: Agilent 490 Micro GC system equipped with PoraPLOT Q column module

Results and Discussion

The method achieved full resolution of dibromomethane from the methane background in approximately 240 seconds. The sharp peak at the retention time corresponding to CH2Br2 demonstrates excellent selectivity and minimal interference. The short analysis time and simple isothermal operation facilitate rapid turnaround without sacrificing precision.

Practical Benefits

• Speed: Complete analysis in under 4 minutes increases sample throughput.
• Simplicity: No temperature or pressure programming reduces method complexity and maintenance.
• Sensitivity: Clear detection of 50 ppm dibromomethane in methane supports trace-level monitoring.
• Reliability: Robust micro-GC design ensures stable performance in routine QA/QC workflows.

Future Trends and Applications

Advances in micro-GC column materials and detector technologies may further lower detection limits and shorten run times. Integration with on-site monitoring platforms or process analyzers could enable continuous real-time tracking of halogenated contaminants in industrial gas streams. Analytical software enhancements will simplify data handling and method transfer between laboratories.

Conclusion

The described micro-GC method using an Agilent PoraPLOT Q column delivers rapid, reliable quantification of dibromomethane in methane. Its straightforward operation, fast cycle times, and clear separation make it well suited for routine environmental and quality control applications.

Reference

Agilent Technologies, Inc. Application Note A01631, October 31, 2011.