EPA Method 1664B Extractions Using the Biotage® Horizon 3100 with In-Line Drying Using ISOLUTE® Sodium Sulfate Drying Cartridges

Importance of the Topic

Oil and grease from industrial and municipal wastewater pose significant risks to aquatic ecosystems and can clog infrastructure. Reliable quantification of hexane extractable material (HEM) according to EPA Method 1664B ensures regulatory compliance and environmental protection.

Objectives and Study Overview

This study demonstrates an automated inline solid-phase extraction (SPE) and drying workflow for measuring HEM using the Biotage Horizon 3100 paired with ISOLUTE® sodium sulfate cartridges. Key goals include meeting EPA 1664B criteria for method detection limit (MDL), precision, and recovery while minimizing operator involvement.

Methodology and Instrumentation

• Sample Preparation: 17 L of deionized water acidified to pH <2; spiked for MDL (4 mg/L HEM) and initial precision and recovery (IPR, 40 mg/L HEM).
• Extraction: 90 mm Pacific Premium disks mounted on the Horizon 3100; inline drying via ISOLUTE sodium sulfate cartridges; sequential conditioning, loading, air drying, rinsing, and elution with n-hexane and methanol.
• Concentration: Speed-Vap® system at 40 °C and 80 psi compressed air; evaporate extracts to a thin hexane layer; final drying in a fume hood.
• Analysis: Weigh extracts in 105 mm aluminum pans using a Sartorius analytical balance and calculate HEM concentration (mg/L).

Used Instrumentation

• Biotage Horizon 3100 Oil and Grease Extraction System
• Speed-Vap Automated Solvent Evaporation System (P/N 200-1000-04)
• ISOLUTE Sodium Sulfate Drying Cartridges (P/N 802-0250-M)
• Pacific Premium Oil & Grease Disks, 90 mm (P/N 1664-100-PHT)
• Analytical Balance (Sartorius)

Main Results and Discussion

The complete extraction and evaporation cycle for three QC samples requires approximately one hour per system. MDL experiments produced an MDL below 1.4 mg/L (EPA requirement) with a precision (s) of 0.3406. IPR recoveries averaged 88 % (range 87.25–88.75 %) with precision well below the 11 % threshold. Blank samples showed negligible contamination (< MDL).

Benefits and Practical Applications

• Automated inline extraction and drying reduces manual handling and operator bias.
• Compliance with EPA 1664B criteria for MDL, precision, and recovery.
• Enhanced throughput allows routine analysis of multiple samples with reproducible performance.

Future Trends and Potential Applications

Anticipated developments include integration of inline detectors (e.g., FTIR, fluorescence), adoption of greener solvents, miniaturized SPE formats for field deployment, and real-time monitoring capabilities for continuous wastewater analysis.

Conclusion

The presented automated SPE and inline drying approach using Biotage instrumentation reliably meets EPA Method 1664B requirements for HEM quantification. Inline sodium sulfate cartridges and controlled evaporation streamline the workflow, delivering precise recoveries and low detection limits while minimizing contamination and operator intervention.

References

• EPA Method 1664B: n-Hexane Extractable Material (HEM; Oil and Grease) by Extraction and Gravimetry, U.S. Environmental Protection Agency, 2010.