C1 to C5 Hydrocarbons

Significance of the topic

Gas chromatography with capillary columns offers precise separation of C1–C5 hydrocarbons, essential for refining process control, product quality assessment, and regulatory compliance.

Objectives and study overview

The application note demonstrates the resolution of twelve light hydrocarbons using a bonded dimethylpolysiloxane PHAT Phase™ capillary column under a defined temperature program.

Methodology and instrumentation

The analysis utilized a 30 m × 0.32 mm I.D. capillary column with a 10 µm film of dimethylpolysiloxane. Temperature was programmed from 35 °C (3 min hold) ramping at 2 °C/min to 45 °C, then 6 °C/min to 100 °C. Injector and detector (FID) temperatures were 150 °C and 250 °C, respectively.

Key results and discussion

The method achieved baseline separation of methane, ethane, propane, isobutane, an isobutylene & 1-butene co-eluting pair, n-butane, trans-2-butene, cis-2-butene, 1-pentene, n-pentane, trans-2-pentene, and cis-2-pentene. Peak elution order corresponded to molecular weight and volatility.

Benefits and practical applications

• High resolution of light hydrocarbon mixtures
• Reliable quantification for process monitoring
• Broad applicability in refining QA/QC

Future trends and opportunities

Advancements may include faster temperature ramps, novel stationary phases for improved selectivity, comprehensive two-dimensional GC (GC×GC), and automation via headspace or flow modulation to enhance throughput and sensitivity.

Conclusion

The described GC method provides an effective, reproducible approach for routine analysis of light petrochemical fractions, ensuring accurate compositional data for industrial applications.

Reference

• Quadrex Corporation. GC Capillary Column Applications: Petrochemical. Application Note.