Orthogonal Selectivity for Separation of Light and Heavy Petroleum Hydrocarbons by 2D GC using Zebron™ ZB-1HT Inferno™ and ZB-35HT Inferno GC Columns

Importance of the Topic

Complex petroleum hydrocarbon mixtures present significant challenges for conventional one-dimensional gas chromatography due to coelutions and limited peak capacity. Two-dimensional GC offers enhanced peak capacity and orthogonal selectivity to fully resolve light and heavy hydrocarbon fractions, enabling detailed compositional analysis essential for refining, quality control, and research.

Objectives and Overview of the Study

This work aimed to evaluate the performance of a two-dimensional GC method using a Zebron ZB-1HT Inferno column in the first dimension and a Zebron ZB-35HT Inferno column in the second dimension. The study focused on separating a gas oil petroleum fraction and a heavy petroleum fraction, mapping individual aliphatic and aromatic species up to C42, and demonstrating the orthogonal selectivity afforded by these columns.

Instrumentation Used

• Gas Chromatograph: Agilent 7890A system modified with a gas-phase microfluidics interface
• First Dimension Column: Zebron ZB-1HT Inferno (100% dimethylpolysiloxane, 15 m × 0.10 mm × 0.10 μm)
• Second Dimension Column: Zebron ZB-35HT Inferno (35% phenyl, 65% dimethylpolysiloxane, 5 m × 0.25 mm × 0.18 μm)
• Carrier Gas: Hydrogen (1.0 mL/min first dimension; 2.4 mL/min second dimension)
• Injection: Split 20:1 at 250 °C, 1 μL sample, ZebronPLUS Z-Liner
• Detector: Flame Ionization (FID) at 360 °C, 100 Hz acquisition
• Oven Programs: Optimized temperature ramps up to 400–430 °C for comprehensive elution

Main Results and Discussion

The two-dimensional analysis successfully resolved complex hydrocarbon mixtures up to C42. The first dimension provided boiling-point separation of linear and branched alkanes, while the second dimension exploited pi-pi interactions to separate aromatic species. Key compound classes separated include:

• Linear alkanes (n-paraffins and iso-paraffins)
• Linear alkenes (olefins)
• Cyclic alkanes
• Aromatics: one-ring derivatives (benzene and tetralin), two-ring (naphthalene derivatives), di-benzene, three-ring, four-ring, and five-ring compounds

The Zebron Inferno columns feature Engineered Cross-linking™ bonding and a high-temperature-stable polyimide coating, delivering extremely low bleed and extended lifetime at temperatures up to 430 °C.

Benefits and Practical Applications

• Comprehensive resolution of light and heavy hydrocarbon fractions with minimal coelution
• High-temperature capability enabling full elution of refractory compounds
• Orthogonal selectivity for precise distinction of aliphatic and aromatic species
• Enhanced sensitivity and dynamic range using hydrogen carrier gas and FID detection
• Valuable for refining process optimization, quality control, environmental monitoring, and research applications

Future Trends and Opportunities

• Integration of rapid-scanning detection technologies to capture ultra-narrow second-dimension peaks
• Application of automated data analysis tools and chemometric methods for matrix complexity
• Expansion of two-dimensional GC to other complex organic systems, such as biofuels and environmental pollutants
• Development of advanced microfluidic interfaces to reduce dead volume and improve modulation

Conclusion

The combination of Zebron ZB-1HT Inferno and ZB-35HT Inferno columns in a two-dimensional GC setup provides robust high-temperature operation and true orthogonal selectivity. This approach delivers detailed molecular mapping of complex petroleum fractions, facilitating improved process control and analytical insight.

Acknowledgement: The authors thank IRCELYON for collaboration and assistance in method development.