ASTM D6730 Detailed Hydrocarbon Analysis of Spark Ignition Fuel using Zebron™ ZB-DHA-PONA Gas Chromatography Column

Importance of the Topic

Detailed hydrocarbon analysis (DHA) of spark ignition fuels is critical for ensuring compliance with regulatory specifications and maintaining refinery process control. The complexity of modern fuel blends, which combine virgin straight-run naphtha with streams from FCC, coking, steam cracking and alkylation units as well as oxygenated additives, demands precise group-type quantitation to optimize engine performance and minimize emissions.

Objectives and Study Overview

This application note describes the use of the ASTM D6730-01 DHA method to separate and quantify paraffins, isoparaffins, olefins, naphthenes, aromatics and oxygenates in spark ignition fuels. The study demonstrates how combining a 100 % dimethylpolysiloxane column (ZB-DHA-PONA) with a phenyl-tuned guard column (ZB-DHA-PONA-TUNE) enhances resolution of critical components such as benzene, toluene and oxygenates.

Methodology and Instrumentation

The analytical setup included a dual-column union of a 5 m × 0.25 mm × 1.0 μm ZB-DHA-PONA-TUNE column (5 % phenyl phase) and a 100 m × 0.25 mm × 0.50 μm ZB-DHA-PONA column (100 % dimethylpolysiloxane). Key operating conditions were:

• Injection: split 150 : 1 at 200 °C, 0.2 μL sample volume
• Carrier gas: hydrogen at 2 mL/min (constant flow)
• Oven program: 30 °C (8.5 min), ramp to 48 °C at 22 °C/min (27 min), ramp to 141 °C at 3 °C/min (1 min), ramp to 275 °C at 1 °C/min (2 min)
• Detector: flame ionization at 275 °C

Main Results and Discussion

The combined column configuration achieved separation of 29 fuel components with high plate counts exceeding the ASTM D6730 requirement of 400 000 plates for the pentane peak. The phenyl-tuned guard column provided enhanced selectivity for aromatic–alkane pairs, improving the resolution of benzene and toluene from paraffins and cycloparaffins. The low-bleed, cross-linked stationary phases and deactivated fused silica surfaces ensured sharp, symmetric peaks for both polar and nonpolar compounds.

Benefits and Practical Applications

The ZB-DHA-PONA system delivers:

• Efficient separation of paraffins, isoparaffins, olefins, naphthenes, aromatics and oxygenates in a single run
• Robust performance at high temperatures (up to 360 °C) due to flexible polyimide coating
• Low bleed and stable baseline for reliable quantitation
• Compliance with ASTM D6730-01 requirements for regulatory testing and quality control

Future Trends and Potential Applications

Advancements may include further miniaturization of column dimensions for faster analysis, development of stationary phases tailored to emerging biofuel additives, and integration with mass spectrometric detection for enhanced compound identification. Automated data processing and real-time monitoring of blending streams could further improve refinery QA/QC workflows.

Conclusion

The combination of a ZB-DHA-PONA column with a ZB-DHA-PONA-TUNE guard column offers an optimal solution for detailed hydrocarbon analysis of spark ignition fuels. This configuration meets ASTM D6730-01 specifications, achieving high efficiency and selectivity for complex fuel matrices, and supports regulatory compliance and process quality control in the fuel industry.

Reference

Nelson T, Dhandapani R, Aqeel Z. ASTM D6730 Detailed Hydrocarbon Analysis of Spark Ignition Fuel using Zebron ZB-DHA-PONA Gas Chromatography Column. Phenomenex Application Note TN-2084; 2019.