Hydrocarbons, C1 – C4 - Analysis of impurities in butane

Significance of the Topic

The precise detection and quantification of C1–C4 hydrocarbons and trace impurities in butane are essential for ensuring fuel quality, process safety and regulatory compliance in petrochemical and energy industries. Rapid screening methods support efficient production control and reduce the risk of off-specification products.

Objectives and Study Overview

This study demonstrates a fast gas chromatography method capable of baseline separation of methane, ethane, propane and butane within 12 minutes. The goal is to provide an analytical workflow for routine monitoring of gaseous contaminants in commercial butane streams.

Methodology

An optimized temperature program starting at 30 °C, held for 2 minutes, followed by a linear ramp of 10 °C/min to 250 °C, ensures sharp peak resolution. Helium is used as carrier gas at 210 kPa. A split injection (1:100) minimizes column overload while delivering reproducible peak areas for trace components.

Used Instrumentation

• Gas chromatograph with capillary inlet
• Agilent CP-SilicaPLOT column, 30 m x 0.32 mm, df 4 µm
• Split injector, 200 °C
• Flame ionization detector at 250 °C
• Helium carrier gas at 2.1 bar

Main Results and Discussion

The method achieves clear separation of four hydrocarbon peaks: methane (1), ethane (2), propane (3) and butane (4). Retention times are reproducible, with negligible coelution. The FID response is linear across relevant concentration ranges, enabling low-level impurity detection.

Benefits and Practical Applications

• Rapid turnaround for quality control laboratories
• High sensitivity for trace impurities
• Robust operation with standard instrumentation
• Minimal sample preparation and maintenance

Future Trends and Potential Applications

Advances may include faster temperature ramps, microfluidic columns for on-site analysis and coupling with mass spectrometry for confirmatory identification. Integration into automated process analyzers could further streamline real-time monitoring in refining and gas processing facilities.

Conclusion

This application note presents a reliable GC-FID protocol for fast, reproducible analysis of C1–C4 hydrocarbons in butane. The approach meets industry demands for speed, sensitivity and operational simplicity, supporting routine impurity screening.

Reference

Agilent Technologies, Inc. Application Note A01290, First published prior to 11 May 2010, updated 31 October 2011.