Hexane Extractable Material (Oil & Grease) Analysis with Automated Solid Phase Extraction Using the Biotage Horizon 5000

Importance of the Topic

Hexane extractable material, commonly referred to as oil & grease (HEM/OG), is a critical indicator in water quality monitoring and regulatory compliance.
The measurement helps protect wastewater treatment plants from malfunction due to lipid and hydrocarbon contamination.

Objectives and Article Overview

• Assess automated solid phase extraction (SPE) for HEM analysis using the Biotage Horizon 5000.
• Demonstrate compliance with US EPA Method 1664B precision and recovery requirements.
• Compare performance of different disk sizes (100 mm vs. 47 mm) and inclusion of pre-filters.

Methodology and Instrumental Setup

• Sample preparation: DI water spiked at 40 ppm oil & grease standard, acidified to pH <2.
• Automated SPE performed on Biotage Horizon 5000 with SPE-DEX module.
• Sorbents: Pacific Premium disks (90/100 mm and 47 mm) and Atlantic Fast Flow pre-filters.
• Drying: DryDisk solvent drying under controlled N2 blanket.
• Elution: Sequential hexane elution steps configured per EPA 1664B parameters.
• Gravimetric determination: Evaporation via Speed-Vap IV and final mass measurement yields mg/L HEM.

Main Results and Discussion

• Recoveries ranged from 95 % to 99 % across configurations, meeting regulatory criteria.
• Relative standard deviations were below 2 %, demonstrating high precision.
• Use of pre-filters did not materially affect extraction efficiency, facilitating higher throughput.
• Method detection limits were preserved despite automation, ensuring analytical sensitivity.

Benefits and Practical Applications

• Automation reduces manual handling errors and increases sample throughput.
• Modular disk and filter options allow adaptation to varying sample matrices.
• Compatible with municipal and industrial QA/QC workflows for routine oil & grease monitoring.

Future Trends and Potential Applications

Ongoing developments in SPE automation may integrate on-line MDL confirmation and coupling to spectrometric detection for targeted hydrocarbon speciation.
Miniaturized or field-deployable automated extraction systems could expand real-time monitoring capabilities.

Conclusion

The Biotage Horizon 5000 automated SPE protocol successfully delivers robust, reproducible HEM extraction that complies with US EPA 1664B standards, offering an efficient and reliable solution for water quality laboratories.

References

1. US EPA Method 1664, Revision B: n-Hexane Extractable Material (Oil & Grease) and Gel-Treated n-Hexane Extractable Material (2010).
2. ISO 11349:2010 Water quality—Determination of low-volatility lipophilic substances—Gravimetric method.
3. Standard Methods 5520G, 21st Edition, Analysis of Water and Wastewater.
4. Leung V. and Ebitson M., AN102-HOR: Modern HEM Analysis in Wastewater Samples (Biotage).
5. Gallagher D., AN025-HOR: Automated SPE for EPA 1664A/B Compliance (Biotage).