ASTM D 4815 – the Determination of Oxygenated Compounds in Gasoline

Significance of the topic

The regulation of reformulated gasoline with oxygenates is critical for reducing emissions and meeting environmental standards set by the EPA and CARB. Ensuring accurate measurement of alcohol and ether additives such as ethanol and MTBE supports regulatory compliance and protects air quality.

Objectives and study overview

This application note presents a gas chromatographic method, compliant with ASTM D 4815, for the determination of oxygenated compounds in gasoline. The goal is to demonstrate a reliable, fully automated GC setup capable of quantifying C1–C4 alcohols and key ethers in finished motor gasoline.

Methodology and instrumentation

The analysis employs an Agilent GC system configured with:

• A split/splitless injector (model 1079) for sample introduction.
• A two-column arrangement: CP-TCEP for Alcohols in Gasoline to pre-separate low-boiling non-polar matrix, and CP-Sil 5 CB to resolve higher boiling and polar analytes.
• A ten-port rotary valve enabling backflush of unwanted fractions and transfer of target compounds.
• A flame ionization detector (FID) for quantitation; an optional thermal conductivity detector (TCD) may assist in valve timing.
• Electronic flow control to ramp carrier gas pressure during backflush, reducing cycle time by ~40%.
• Agilent chromatography software for automated data acquisition, calibration curve generation using multi-component standards, and linearity assessment.

Main results and discussion

Chromatograms of a multicomponent test blend illustrate baseline separation of fourteen oxygenates plus benzene and TAME. Automated calibration using an internal standard (1,2-dimethoxyethane) and multiple concentration levels yielded robust linearity and reproducible retention times.

Benefits and practical applications

This GC configuration offers laboratory and refinery QA/QC teams:

• Fast, fully automated analysis of reformulated gasoline samples.
• Comprehensive quantitation of alcohols (methanol to n-butanol) and ethers (MTBE, ETBE, DIPE, t-Amyl alcohol).
• Reduced solvent consumption and operator intervention through backflush technology.
• Regulatory confidence by conforming precisely to ASTM D 4815 requirements.

Future trends and possibilities

Advances may include coupling GC to mass spectrometry for enhanced specificity, miniaturized systems for on-site testing, integration of advanced data analytics for real-time quality monitoring, and development of green analytical methods to reduce environmental impact.

Conclusion

The Agilent GC system configured per ASTM D 4815 delivers reliable, precise, and efficient quantitation of oxygenates in gasoline, ensuring compliance with EPA and CARB mandates while optimizing laboratory throughput.

References

• ASTM D 4815. Standard Test Method for the Determination of MTBE, ETBE, TAME, DIPE, tertiary-Amyl Alcohol, and C1 to C4 Alcohols in Gasoline by Gas Chromatography. ASTM International, West Conshohocken, PA, USA.