Determination of Gasoline Range Organics (GRO)

Significance of the Topic

Gasoline range organic compounds (C5–C12) are critical indicators of fuel quality, performance and regulatory compliance. Accurate profiling of these hydrocarbons ensures proper engine operation, environmental safety and adherence to industry standards. Gas chromatography with flame ionization detection (GC–FID) remains a benchmark technique for rapid, reliable analysis in petrochemical laboratories.

Objectives and Overview

This application demonstrates a robust GC–FID method for the determination of eleven key gasoline-range hydrocarbons. The focus is on achieving baseline separation, reproducible retention times and quantification suitable for quality control and production monitoring in refining operations.

Methodology and Instrumentation

The separation employs a capillary column coated with dimethylpolysiloxane (10 m length, 0.53 mm internal diameter, 1.0 µm film thickness). The temperature program starts at 35 °C with a 4 minute hold, then ramps at 20 °C/min to 320 °C. Injector temperature is set to 225 °C, while the detector (FID) operates at 320 °C. Helium is used as the carrier gas at a constant flow of 10 mL/min.

Used Instrumentation

• Gas chromatograph equipped with split/splitless injector
• Flame ionization detector (FID)
• Capillary column: dimethylpolysiloxane, 10 m × 0.53 mm I.D. × 1.0 µm film
• Carrier gas: Helium at 10 mL/min

Main Results and Discussion

Baseline separation was achieved for eleven analytes, including pentane, methylpentanes, hexanes, benzene, isooctane, heptane, toluene, ethylbenzene and trimethylbenzenes. Retention times were consistent with relative standard deviations below 1%. The method provided clear resolution of isomeric pairs (p-xylene/m-xylene and 2,2,4-trimethylpentane/isooctane), demonstrating selectivity of the dimethylpolysiloxane phase.

Benefits and Practical Applications

• Rapid analysis suitable for high-throughput quality control
• Reproducible quantification of key hydrocarbons in gasoline blends
• Capability to detect and resolve structural isomers critical for octane rating
• Compliance with industry and environmental regulations

Future Trends and Potential Applications

Advances in column technology may lead to shorter analysis times and improved resolution. Coupling GC with mass spectrometry enables more detailed compositional analysis and trace impurity detection. Automation and online sampling are expected to streamline petrochemical workflows and reduce manual intervention. Green carrier gases and energy-efficient ovens could enhance sustainability.

Conclusion

The presented GC–FID method delivers reliable separation and quantification of gasoline-range organics. Its simplicity, robustness and compatibility with routine petrochemical analyses make it an effective tool for refinery QC and regulatory testing.