The Determination of C1 to C5 Hydrocarbons in Gas Streams Using the PerkinElmer Swafer Technology

Significance of the Topic

Accurate and rapid analysis of light hydrocarbons (C1–C5) in refinery and process gas streams is essential for product quality control, energy value determination and process optimization.

Objectives and Study Overview

This work presents a novel method combining a pressure-balanced Swafer backflushing device with capillary columns under isothermal conditions to achieve complete separation and quantification of C1–C5 hydrocarbons and total C6+ in a single 5.4-minute GC cycle.

Methodology and Instrumentation

A capillary precolumn and analytical column are arranged via an S-Swafer device that reverses pressure to backflush higher-boiling C6+ fraction to the detector. The sequence monitors:

• The initial injection plug
• Precolumn separation of C1–C5
• Backflush of C6+ components
• Final analytical column chromatography of C1–C5

The method uses timed pressure programming and isothermal operation at 160 °C to minimize cycle time.

Instrumentation Used

• Gas chromatograph: PerkinElmer Clarus 680
• Backflush device: PerkinElmer S-Swafer
• Columns: 15 m×0.25 mm×1.0 µm Elite-1 precolumn; 30 m×0.32 mm Al2O3 PLOT analytical column
• Split/Splitless injector with restrictor capillaries
• Detector: Flame ionization (200 °C, Air 450 mL/min, H2 45 mL/min)

Results and Discussion

The method achieves baseline separation of methane through pentane within 5 minutes. Four chromatographic zones enable serial detection of injection, precolumn elution, backflush fraction, and analytical elution. A 100-injection sequence demonstrated relative standard deviations below 0.5% for most analytes, confirming excellent repeatability. Application to a liquid petroleum gas sample further illustrated versatility.

Benefits and Practical Applications

• Rapid analysis with 5.4 min cycle time
• Single detector for multi-zone monitoring
• Reduced mechanical complexity versus rotary valves
• High precision suitable for refinery QA/QC and industrial gas analysis

Future Trends and Opportunities

Further developments may include integration with automated sampling systems, coupling to mass spectrometry for enhanced selectivity, miniaturized or portable GC configurations, and real-time process monitoring for trace hydrocarbons.

Conclusion

This Swafer-based backflush capillary GC method delivers fast, precise and robust analysis of C1–C5 and C6+ hydrocarbons in gas streams using a single detector under isothermal conditions.

Reference

• Tipler A. The Determination of C1 to C5 Hydrocarbons in Gas Streams Using the PerkinElmer Swafer Technology; PerkinElmer Inc.; 2011.