Determination of Total Petroleum Hydrocarbons in Rubble and Soils by Accelerated Solvent Extraction and GC-FID

Significance of the topic

Rapid and reliable quantification of total petroleum hydrocarbons (TPH) in soils and rubble is essential for environmental assessment and remediation. Traditional extraction methods are time-intensive and consume large solvent volumes. The combination of accelerated solvent extraction (ASE) with in-cell cleanup and GC-FID addresses these limitations by offering faster turnaround, reduced solvent use, and integrated cleanup in compliance with regulatory standards.

Objectives and study overview

This work evaluates an ASE-GC-FID procedure for determining total petroleum hydrocarbons in contaminated soils and construction debris. The method is benchmarked against the UNI EN 14039:2005 standard, targeting hydrocarbon fractions >C12 and C10–C40 at spike levels of 25, 50, and 750 mg/kg. Method performance metrics such as recovery, precision, and chromatographic resolution are assessed.

Instrumentation

• Binder ED53 oven for sample drying
• Sartorius analytical balance for weighing samples and standards
• Fritsch Pulverisette planetary ball mill for sample homogenization
• Thermo Scientific Dionex ASE 350 accelerated solvent extractor with 34 mL stainless steel cells and in-cell silica gel cleanup
• Thermo Scientific Rocket Evaporator with Rocket Flip-Flop vials for direct concentration into GC vials
• Thermo Scientific FOCUS GC system with TRACE TR-5 column (30 m × 0.25 mm × 0.25 μm) and flame ionization detector (FID)

Main results and discussion

• ASE parameters: n-hexane solvent, 100 °C, one static cycle of 5 min, 60% rinse volume, 90 s purge, total extraction time 20 min, solvent consumption 40 mL per sample.
• GC conditions: helium carrier at 2.0 mL/min, oven program from 45 °C (1 min) ramping at 25 °C/min to 340 °C (2 min), splitless injection (0.8 min), FID at 340 °C, 2 μL injection volume.
• Spike recoveries for the >C12 fraction ranged from 84.0% to 100.5% with RSDs ≤ 5.8%. For the C10–C40 fraction, recoveries were 79.0%–96.6% with RSDs ≤ 6.0%, fully meeting UNI EN 14039:2005 criteria.
• Chromatographic traces showed clear integration boundaries between n-decane (C10) and n-tetracontane (C40). In a heavily polluted field sample, diesel-range hydrocarbons (C11–C18) dominated the profile.
• In-cell cleanup effectively removed high-molecular-weight interferences, protecting the chromatographic system and eliminating offline purification steps.

Benefits and practical applications of the method

• Significantly reduced analysis time: 20 min per sample versus up to 18 h for Soxhlet extraction.
• Low solvent usage: 40 mL of n-hexane instead of hundreds of milliliters of halogenated solvents.
• Integrated extraction and cleanup: avoids manual Florisil column procedures.
• Direct concentration into GC vials using Rocket Evaporator: eliminates nitrogen blowdown and transfer losses.
• Compliance with European norm UNI EN 14039:2005 for soils and rubble analysis.

Future trends and opportunities

• Coupling ASE to mass spectrometric detection for enhanced selectivity and lower limits of quantification.
• Extension of in-cell cleanup strategies to other contaminant classes, such as polycyclic aromatic hydrocarbons and emerging pollutants.
• Development of miniaturized and automated extraction-analysis workflows for high-throughput environmental monitoring.
• Adoption of greener solvents and energy-efficient instrumentation to reduce environmental footprint.
• Integration of field-deployable ASE systems for on-site rapid screening of hydrocarbon contamination.

Conclusion

The ASE-GC-FID approach with in-cell cleanup delivers rapid, accurate, and reproducible determination of total petroleum hydrocarbons in soils and rubble. It achieves high recoveries, low variance, and regulatory compliance while minimizing solvent use and hands-on time. This streamlined workflow enhances laboratory productivity and supports effective environmental management.

References

• Ezzell J; Richter B; Francis E. Selective Extraction of Polychlorinated Biphenyls from Fish Tissue Using Accelerated Solvent Extraction. American Environmental Laboratory. 1996;8(12):12–13.
• Thermo Fisher Scientific. Selective Extraction of PCBs from Fish Tissue Using Accelerated Solvent Extraction (ASE). Application Note 322; 1996.
• Thermo Fisher Scientific. Determination of PCBs in Large-Volume Fish Tissue Samples Using ASE. Application Note 342; 2000.
• Björklund E; Muller A; von Holst C. Comparison of Fat Retainers in Accelerated Solvent Extraction for the Selective Extraction of PCBs from Fat-Containing Samples. Analytical Chemistry. 2001;73:4050–4053.
• Sporring S; Björklund E. Selective Pressurized Liquid Extraction of PCBs from Fat-Containing Food and Feed Samples. Journal of Chromatography A. 2004;1040:155–161.
• Haglund P; Sporring S; Wiberg K; Björklund E. Shape-Selective Extraction of PCBs and Dioxins from Fish and Fish Oil Using In-Cell Carbon Fractionation. Analytical Chemistry. 2007;79:2945–2951.
• Thermo Fisher Scientific. Determination of Perchlorate in Vegetation Samples Using ASE and Ion Chromatography. Application Note 356; 2006.
• Gentili A; Perret D; Marchese S; Sergi M; Olmi C; Curini R. Accelerated Solvent Extraction and Confirmatory Analysis of Sulfonamide Residues in Raw Meat and Infant Foods by LC-ESI-MS/MS. Journal of Agricultural and Food Chemistry. 2004;52:4614–4624.
• Björklund E; Sporring S; Wiberg K; Haglund P; von Holst C. New Strategies for Extraction and Cleanup of Persistent Organic Pollutants from Food and Feed Samples Using Selective Pressurized Liquid Extraction. Trends in Analytical Chemistry. 2006;25(4):318–325.
• Hussen A; Westbom R; Megersa N; Retta N; Mathiasson L; Björklund E. Optimization of Pressurized Liquid Extraction for the Determination of p,p’-DDT and p,p’-DDE in Aged Contaminated Ethiopian Soils. Analytical and Bioanalytical Chemistry. 2006;386(5):1525–1533.
• Hussen A; Westbom R; Megersa N; Mathiasson L; Björklund E. Development of a Pressurized Liquid Extraction and Cleanup Procedure for the Determination of Alpha-Endosulfan, Beta-Endosulfan and Endosulfan Sulfate in Aged Contaminated Ethiopian Soils. Journal of Chromatography A. 2006;1103:202–210.
• Sporring S; von Holst C; Björklund E. Selective Pressurized Liquid Extraction of PCBs from Food and Feed Samples: Effects of High Lipid Amounts and Lipid Type on Fat Retention. Chromatographia. 2006;64(9–10):553–557.
• Wiberg K; Sporring S; Haglund P; Björklund E. Selective Pressurized Liquid Extraction of Polychlorinated Dibenzo-p-dioxins, Dibenzofurans and Dioxin-like Polychlorinated Biphenyls from Food and Feed Samples. Journal of Chromatography A. 2007;1138:55–64.
• Hussen A; Westbom R; Megersa N; Mathiasson L; Björklund E. Selective Pressurized Liquid Extraction for Multi-residue Analysis of Organochlorine Pesticides in Soil. Journal of Chromatography A. 2007;1152:247–253.
• Thermo Fisher Scientific. Fast Determination of Acrylamide in Food Samples Using ASE Followed by Ion Chromatography with UV or MS Detection. Application Note 409; 2003.
• Thermo Fisher Scientific. Extraction and Cleanup of Acrylamide in Complex Matrices Using ASE Followed by Liquid Chromatography–Tandem Mass Spectrometry. Application Note 358; 2007.
• Poerschmann J; Carlson R. New Fractionation Scheme for Lipid Classes Based on ‘In-Cell Fractionation’ Using Sequential Pressurized Liquid Extraction. Journal of Chromatography A. 2006;1127:18–25.
• Poerschmann J; Trommler U; Biedermann W; Truyen U; Lucker E. Sequential Pressurized Liquid Extraction to Determine Brain-Originating Fatty Acids in Meat Products as Markers in Bovine Spongiform Encephalopathy Risk Assessment Studies. Journal of Chromatography A. 2006;1127:26–33.