NEMC: Analysis of Diesel Range Organics (DRO) and Motor/Lube Oil Range Organics (ORO) in Ultrashort Run Time

Significance of the Topic

This work focuses on the rapid quantification of semi-volatile petroleum hydrocarbons, specifically diesel range organics (DRO, C10–C28) and oil range organics (ORO, C28–C40). Rapid assessment of these compounds is critical for environmental site remediation, regulatory compliance, and industrial quality control where traditional methods require lengthy chromatographic runs.

Objectives and Study Overview

The main goal was to develop and validate an ultrashort-run time gas chromatography flame ionization detection (GC-FID) method for direct analysis of DRO and ORO in under two minutes. The study compared performance using helium and hydrogen as carrier gases and evaluated calibration linearity, accuracy, and peak resolution across relevant concentration ranges.

Methodology

A temperature programmable fast (FTP) column (5 m × 0.25 mm × 0.25 µm) with resistive heating coils enabled ramp rates up to 280 °C/min for rapid separation. A Shimadzu GC-2030 system with split/splitless injector and FID was employed. Standards spanning 10 to 500 ppm were prepared in dichloromethane for five‐point calibrations. Automated switching between He and H₂ carrier gases was facilitated by an inline gas selector.

Instrumentation Used

• Shimadzu GC-2030 GC system
• FTP-MXT-1 column (5 m × 0.25 mm × 0.25 µm)
• Shimadzu SPL injector and AOC-20 autosampler
• Shimadzu FID detector
• Inline gas selector for He/H₂ switching

Main Results and Discussion

All target analytes eluted within 1.5 min, achieving full C10–C40 separation in under two minutes. Both helium and hydrogen carrier gases produced comparable retention times and resolution with correlation coefficients > 0.997. Accuracy deviations were within ±15% across all calibration points. Hydrogen offered slightly faster linear velocities and earlier elution without sacrificing detector response or chromatographic performance.

Benefits and Practical Applications

• Throughput increased tenfold versus conventional methods (EPA 8015), enabling up to 250 samples per 12-hr shift.
• Hydrogen serves as a cost-effective carrier gas alternative to helium.
• Minimal maintenance with long-life septa and syringe allows up to 1000 injections without interruption.
• Applicable to environmental monitoring, site remediation, and industrial process control.

Future Trends and Opportunities

Further optimization could integrate online sample pretreatment and overlapping autosampler functions to reduce per-sample time below three minutes. Expansion to other semi-volatile compound classes or coupling with mass spectrometry for enhanced specificity may extend method applicability. Development of portable ultrafast GC systems could enable field-based screening.

Conclusion

An ultrafast GC-FID method using an FTP column and automated He/H₂ switching successfully quantified DRO and ORO in under two minutes with high accuracy and resolution. The approach significantly increases sample throughput, reduces operational costs, and offers a robust alternative to conventional EPA methods.