Extraction of EPA Method 625.1 Semi-Volatile Analytes from Wastewater Using the Biotage® Horizon 5000, DryDisk® Solvent Drying System and TurboVap® II

Importance of the Topic

Monitoring semi-volatile organic pollutants in wastewater is essential for environmental protection and compliance with EPA standards. Reliable extraction and analysis of diverse analytes ensure accurate quantification of priority pollutants in wastewater matrices.

Objectives and Study Overview

This study applies EPA Method 625.1 using a novel automated SPE workflow with the Biotage Horizon 5000 to streamline the extraction of basic, neutral, and acidic semi-volatile analytes from wastewater. It aims to evaluate method performance at two spike levels (50 and 100 µg/L) and demonstrate efficient solvent drying and concentration with Biotage DryDisk and TurboVap II systems.

Methodology and Instrumentation

Extraction and concentration were conducted as follows:

• Sample preparation: 1 L deionized water acidified to pH < 2, spiked with target analyte mix and surrogates.
• SPE: Mixed-mode Atlantic 8270 One-Pass disks coupled with Carbon Cartridge Max-Detect using Biotage Horizon 5000; sequential elution in three parts for neutral/acidic, ion exchange, and carbon-phase fractions with pH-adjusting rinses.
• Drying: Solvent removal on DryDisk Solvent Drying System under vacuum.
• Concentration: Final volume reduced to 0.9 mL in approximately 1 h 50 min on TurboVap II under 40 °C with nitrogen flow.
• Analysis: GC-MS using a Zebron ZB-Semi Volatiles column (30 m × 0.25 mm, 0.25 µm), helium carrier, split injection, and AMU scan range 35–550.

Key Results and Discussion

Performance assessment at two spike levels revealed:

• Average recoveries for over 100 semi-volatile analytes ranged between 60% and 140%, meeting EPA Method 625.1 criteria.
• Repeatability was high, with percent RSD values typically below 10% for target analytes.
• All six surrogate compounds demonstrated consistent recovery within acceptance limits.
• Method blanks showed no false positives above the 10 µg/L detection limit.

A consistent concentration time of approximately 1 h 50 min was recorded across samples, demonstrating robust throughput.

Benefits and Practical Applications

This workflow offers:

• Automated SPE with reduced hands-on time and minimized pH adjustment steps.
• High recovery and precision across a broad analyte scope, including EPA priority pollutants.
• Efficient solvent removal and concentration compatible with high-throughput laboratories.
• Scalability for regulatory compliance, environmental monitoring, and wastewater treatment testing.

Future Trends and Opportunities

Advances may include:

• Integration of high-resolution mass spectrometry for expanded analyte coverage.
• Miniaturized SPE devices for field-deployable monitoring.
• Continuous online SPE–GC-MS systems enabling real-time analysis.
• Data-driven optimization of extraction protocols using machine learning.

Conclusion

The combination of Biotage Horizon 5000 SPE, DryDisk drying, and TurboVap II concentration delivers a streamlined, robust, and EPA-compliant approach for extracting semi-volatile analytes from wastewater. Consistent recoveries and efficient processing support routine environmental and regulatory analysis.

Instrumental Setup

• Biotage Horizon 5000 automated SPE workstation
• Biotage DryDisk Solvent Drying System with DryDisks
• Biotage TurboVap II solvent evaporator
• GC-MS system with Zebron ZB-Semi Volatiles column and helium carrier

References

United States Environmental Protection Agency. Method 625.1: Base/Neutrals and Acids by GC/MS, December 2016.