Ultrafast Simulated Distillation of Middle Distillates Using ASTM Method D7798 on the Agilent Intuvo Gas Chromatograph

Importance of the topic

Quality control and fuel specification in petroleum and chemical industries rely on accurate boiling range analysis of middle distillates. Simulated distillation using ultrafast gas chromatography delivers rapid, reproducible boiling point distribution, critical for ensuring fuel performance, compliance with standards, and process optimization.

Objectives and overview

This study demonstrates implementation of ASTM D7798 on the Agilent Intuvo 9000 GC, targeting sub-3-minute middle-distillate simulated distillation. Key aims included evaluating retention time precision, validating method performance with reference gas oil, and comparing boiling range results of jet fuel, diesel, and waxy distillate against ASTM D7798 research data and the D2887 referee method.

Methodology

Calibration mixtures containing n-alkanes from C5 to C44 were prepared in carbon disulfide and injected five times. Subsequent validation used an RGO reference sample analyzed in quintuplicate. Three middle-distillate samples were run without dilution or pre-heating. Boiling range calculations were processed in Agilent SimDis software.

Instrumentation used

The Agilent Intuvo 9000 GC featured a direct-heating column oven and sixth-generation EPC for fast temperature ramps (40→360 °C at 160 °C/min) and high flow rates (4 mL/min helium). A 4 m×0.25 mm DB-Sim-Dist column with FID detection was paired with a 7650A autosampler, multimode inlet (split 30:1 at 360 °C), and Intuvo flow and guard chips. FID gases: H2 at 30 mL/min, air at 400 mL/min, N2 make-up at 25 mL/min.

Results and discussion

Calibration runs showed retention time RSDs ≤0.002 min for n-C44 and average recovery of 94% without inlet discrimination. RGO validation matched ASTM reference cut points within ±2 °C and RSDs <0.5%. Analyses of jet fuel, diesel, and waxy distillate completed in 1.5–2.5 min, with boiling range curves agreeing with D2887 and ILS data typically within 2 °C across all cut points.

Benefits and practical application

• Sub-3-minute analysis increases sample throughput and laboratory productivity.
• High retention time precision eliminates need for postrun data alignment.
• Accurate adherence to ASTM standards supports QA/QC in fuel testing.
• Minimal sample preparation streamlines workflow.

Future trends and possibilities

Advances may include integration with high-resolution detectors (e.g., GC-MS), expansion to heavier boiling fractions, enhanced software algorithms for automated data interpretation, and development of portable ultrafast GC systems for on-site fuel analysis. Continuous improvement of column materials and flow control promises further reduction in analysis time and improved separations.

Conclusion

The Agilent Intuvo 9000 GC effectively implements ASTM D7798 for ultrafast simulated distillation of middle distillates, delivering robust performance, precise retention times, and boiling range results comparable to established referee methods. This approach enables rapid, reliable fuel analysis for diverse industrial applications.

References

1. ASTM D2887-16a, Standard Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography, ASTM International, West Conshohocken, PA, 2016.
2. ASTM D7798-15, Standard Test Method for Boiling Range Distribution of Petroleum Distillates With Final Boiling Points up to 538 °C by Ultra Fast Gas Chromatography (UF GC), ASTM International, West Conshohocken, PA, 2015.
3. Research Report RR:D02-1806, Interlaboratory Study to Establish Precision Statements for ASTM D7798, ASTM International, West Conshohocken, PA, 2016.