Determination of Oxygenated Compounds in Gasoline in Compliance with ASTM D4815

Significance of the topic

Reformulated gasoline regulations require a minimum oxygen content to reduce environmental emissions and improve air quality. Accurate determination of oxygenated additives such as alcohols and ethers is essential for refineries to ensure compliance with EPA and CARB standards and to verify fuel quality.

Objectives and Study Overview

This study aims to evaluate a GC method following ASTM D4815 for quantifying C1 to C4 alcohols and common ethers in finished gasoline. The performance of a SCION GC analyzer equipped with a backflush valve and FID detector is assessed in terms of separation efficiency and repeatability.

Methodology

The analysis employs a two-column arrangement. A polar first column separates low-boiling and non-polar compounds, while target oxygenates are diverted and subsequently separated by boiling point on a non-polar second column. A programmed carrier gas pressure profile accelerates analysis time. Calibration uses multi-component standards and 1,2-dimethoxyethane as an internal standard.

Used Instrumentation

• SCION GC system with split splitless injector and ten port rotary backflush valve
• Polar capillary column for initial separation
• Non polar capillary column for oxygenate resolution
• Flame ionization detector maintained at 300°C
• Helium carrier gas with programmed pressure increase during backflush

Key Results and Discussion

The method achieved baseline separation of sixteen compounds including methanol ethanol iso-propanol tert-butanol n-propanol MTBE TAME and higher alcohols. Backflush operation restored baseline between runs. Repeatability tests (n=20) showed relative standard deviations between 0.71 and 1.6 across all analytes, confirming excellent precision.

Benefits and Practical Applications

This GC method offers rapid and reliable quantitation of oxygenates in reformulated gasoline ensuring regulatory compliance. The backflush approach reduces run times and minimizes column fouling improving sample throughput and analytical robustness.

Future Trends and Potential Applications

Integrating mass spectrometric detection can enhance selectivity for co eluting compounds. Advances in micro GC and real time monitoring platforms may enable on site fuel quality testing. Machine learning approaches for chromatogram interpretation could further streamline data processing.

Conclusion

The SCION GC FID system under ASTM D4815 conditions demonstrates efficient separation repeatable quantitation and operational simplicity for oxygenate analysis in gasoline fulfilling regulatory and quality control requirements.

Reference

• SCION Instruments Application Note AN0002 Determination of Oxygenated Compounds in Gasoline in Compliance with ASTM D4815