Aromatic Component Analysis of Gasoline According to ASTM D5580 Using the Brevis GC- 2050 Gas Chromatograph

Importance of the Topic

Determining aromatic hydrocarbons in gasoline is essential for octane rating, regulatory compliance, and environmental protection. Benzene and other aromatics must be accurately quantified to minimize hazardous emissions and ensure fuel quality across production and distribution networks.

Objectives and Study Overview

This application note demonstrates the use of the Shimadzu Brevis GC-2050 gas chromatograph to measure gasoline aromatics in accordance with ASTM D5580. The study aims to optimize dual-column flow path switching to separate and quantify benzene, toluene, ethylbenzene, p/m-xylene, o-xylene, and C9+ aromatics in a single analysis.

Instrumentation Used

• Brevis GC-2050 gas chromatograph
• AOC-30 autosampler
• VB-30-S heated valve box with flow path switching
• Optional thermal conductivity detector (TCD) for switch timing
• Column 1: TCEP 20% micro-packed polar column (0.6 m × 0.8 mm I.D.)
• Column 2: SH-1 non-polar column (30 m × 0.53 mm I.D., 3.0 µm film)
• Flame ionization detector (FID) with He make-up gas, H2 and air flows

Methodology

The method employs two chromatographic conditions (A and B) and three flow paths: (a) sample injection and retention of aromatics on Column 1 while venting non-aromatics; (b) reversal of flow to transfer retained aromatics to Column 2 for further separation; (c) backflush to FID for C9+ aromatics determination. A 1 µL split injection of gasoline spiked with 10 wt% internal standard (2-hexanone) is performed at 200 °C. Column temperatures ramp from 60 °C at 2 °C/min to 115 °C under both conditions, with flow path switching timed to isolate target compounds.

Main Results and Discussion

The dual-column switching approach yielded clean chromatograms free of interfering peaks, confirming selective retention and elution of target aromatics. Calibration curves for each analyte exhibited excellent linearity (R2 ≥ 0.999). Within-lab repeatability (10 injections) and between-lab reproducibility tests showed measurement deviations well within ASTM D5580 permissible limits for all six aromatic components.

Benefits and Practical Applications

• Accurate quantification of six key gasoline aromatics in a single run improves laboratory throughput.
• Compact instrumentation suits routine QA/QC in refineries, analytical services, and research laboratories.
• Adjustable flow path timings enable extension to oxygenate analysis (ASTM D4815) and various gasoline additives.

Conclusion

The Brevis GC-2050 equipped with a heated switching valve reliably performs ASTM D5580 aromatic analysis. The system’s dual-column strategy and precise flow path control deliver high selectivity, linearity, and reproducibility for gasoline quality monitoring.

Future Trends and Potential Applications

Advancements may include automated method optimization, integration with mass spectrometric detectors for trace-level analysis, miniaturized GC systems for field testing, and expanded multi-residue analysis workflows for comprehensive fuel characterization.