Improve GC Analysis of Extractable Petroleum Hydrocarbons

Importance of the Topic

Environmental contamination by petroleum hydrocarbons leaking from underground storage tanks presents serious environmental and health risks. Accurate measurement of extractable petroleum hydrocarbons (EPH) in soil and water is essential for site assessment, regulatory compliance, and human exposure evaluation.

Objectives and Article Overview

This study examines the use of Resprep® EPH fractionation SPE cartridges to improve the gas chromatography analysis of extractable petroleum hydrocarbons. It outlines key methodological challenges in sample preparation and evaluates the performance of these method-specific cartridges against competing products.

Methodology and Instrumentation

• Sample Preparation: Initial extraction with methylene chloride, drying over sodium sulfate, solvent exchange to hexane and concentration to 1 mL.
• Fractionation and Cleanup: Solid phase extraction using Resprep® EPH cartridges (20 mL, 5 g silica bed) conditioned with hexane, followed by aliphatic fraction elution in hexane and aromatic fraction in methylene chloride.
• Sorbent Quality Control: Lot-specific determination of silica activity to standardize hexane elution volumes (17–22 mL), strict packaging in desiccators, and immediate resealing to prevent humidity effects.
• Gas Chromatography: Analysis on a PE Clarus 600 GC with Rtx-5 column (30 m × 0.32 mm ID × 0.25 μm), helium carrier gas, FID at 330 °C, splitless injection at 300 °C.

Main Results and Discussion

Comparative testing revealed that Resprep® cartridges exhibit substantially lower background extractables in the hexane fraction compared to competing products, reducing interference in trace-level quantification. Enhanced uniformity in silica activity across lots improved reproducibility of aliphatic fractionation volumes.

Benefits and Practical Applications

• Reduced Chemical Interference: Minimizes co-extracted contaminants such as phthalates, enhancing detection limits and accuracy.
• Improved Reproducibility: Method-specific testing and certification ensure consistent fractionation performance across shipments.
• Regulatory Compliance: Supports detailed quantification of aliphatic and aromatic EPH fractions in environmental monitoring and site remediation projects.

Future Trends and Potential Applications

Advances in sorbent materials and automated SPE platforms will further streamline EPH analysis. Novel cartridge formats with integrated humidity control and real-time activity monitoring may enhance field and laboratory workflows. Integration with high-resolution mass spectrometry could extend the scope of compound identification.

Conclusion

Resprep® EPH fractionation SPE cartridges offer a robust solution to challenges in extractable petroleum hydrocarbon analysis by providing low background, consistent silica activity, and comprehensive documentation. Their adoption can improve analytical precision, reduce reanalysis, and support environmental decision-making.

Reference

1. Massachusetts Department of Environmental Protection. Method for the Determination of Extractable Petroleum Hydrocarbons (EPH), Revision 1.1, May 2004.
2. Texas Natural Resource Conservation Commission. TNRCC Method 1005, Total Petroleum Hydrocarbon, Revision 03, June 1 2001.
3. Texas Natural Resource Conservation Commission. Draft TNRCC Method 1006, Characterization of C6 to C35 Petroleum Hydrocarbons in Environmental Samples, May 2000.