An Improved Method for Diesel Fractionation Following the Revised Massachusetts EPH Guidelines

Importance of the Topic

Environmental contamination by petroleum hydrocarbons from leaking underground storage tanks remains a critical issue for soil and groundwater quality. Effective fractionation and analysis of diesel and related fuel components under updated regulatory guidelines are essential to assess toxicological risk and guide remediation efforts.

Objectives and Study Overview

This work presents an enhanced extractable petroleum hydrocarbon (EPH) fractionation method aligned with Revision 3 of the Massachusetts EPH guidelines. The aim was to streamline sample processing, improve workflow efficiency, and maintain or improve recovery and resolution of aliphatic and aromatic hydrocarbon classes.

Methodology and Applied Instrumentation

Solid-phase extraction (SPE) cartridges packed with a novel Strata EPH sorbent (5 g/20 mL) were conditioned with hexane, loaded with triplicate samples of aliphatic, aromatic, and surrogate standards (blank, 5 ppm and 50 ppm), then eluted sequentially: 11 mL hexane for aliphatics and 20 mL methylene chloride for aromatics. Final extracts were concentrated to 1 mL.

Gas chromatography was performed on a 30 m × 0.32 mm × 0.25 µm Zebron ZB-5ms column with a 5 % phenyl–95 % dimethylpolysiloxane stationary phase. The oven program started at 60 °C (1 min), ramped at 8 °C/min to 290 °C (6.75 min hold). Injection was splitless (2 µL) at 280 °C, with helium carrier at 3 mL/min. The FID detector was set to 315 °C.

Results and Discussion

• Flow rates through Strata EPH sorbent were increased without loss of recovery, reducing fractionation time from about 50 min to 26 min (over 50 % productivity gain).
• Contamination by plasticizer butylated hydroxytoluene (BHT) was reduced, with Strata EPH cartridges showing < 40 ppm versus up to 75 ppm in conventional silica gel tubes.
• Aliphatic recoveries ranged from 88 % to 112 % (RSD ≤ 8 %), meeting the MAEPH3 requirement of 40–140 %.
• Aromatic recoveries exceeded 67 %, with most above 85 % (RSD ≤ 13 %), and breakthrough of naphthalene and 2-methylnaphthalene was below 5 %.
• Chromatographic separation achieved baseline resolution for aliphatic compounds and most polycyclic aromatic hydrocarbon (PAH) isomers, with critical pairs meeting valley-depth criteria.

Benefits and Practical Applications

• Accelerated SPE fractionation reduces sample turnaround time and labor.
• Lower plasticizer interference improves accuracy at low concentration levels.
• Strong recoveries across hydrocarbon classes support compliance with toxicologically based guidelines.
• Compatibility with existing GC–FID instrumentation facilitates adoption in environmental testing laboratories.

Future Trends and Applications

Advances in sorbent chemistries and miniaturized extraction formats may further compress analysis times and solvent usage. Integration with high-throughput autosamplers and mass spectrometric detection could enhance sensitivity and specificity for emerging contaminants within the petroleum hydrocarbon class. Data-driven optimization of fractionation parameters and automation will drive next-generation EPH protocols.

Conclusion

The combination of Strata EPH SPE cartridges and a Zebron ZB-5ms GC column offers an efficient and robust solution for diesel fractionation under revised Massachusetts EPH guidelines. The method delivers high recoveries, reduced contamination, and significant productivity gains without sacrificing chromatographic performance.

Reference

1. U.S. EPA FY 2005 Semi-Annual Mid-Year Activity Report
2. Massachusetts Department of Environmental Protection Method for the Determination of Extractable Petroleum Hydrocarbons (Revision 1.1, May 2004)
3. Boulder Area Sustainability Information Network. Leaking Underground Storage Tanks Overview