Application of solid-phase extraction and rapid, large-volume injection for routine analysis of environmental samples via U.S. EPA SW-846 Method 8270D

Significance of the Topic

Solid-phase extraction (SPE) and large-volume injection (LVI) are critical enhancements for semivolatile analysis of environmental waters under EPA Method 8270D, addressing challenges in sample preparation, solvent use, analyst labor, and analytical precision. Implementing automated SPE and LVI accelerates routine QA/QC workflows in industrial and environmental laboratories, enabling high throughput and consistent results.

Study Objectives and Overview

Eastman Chemical Co. collaborated with Horizon Technology to integrate automated SPE using the SPE-DEX system with large-volume PTV injection, aiming to eliminate laborious post-extraction concentration and improve semivolatile compound analysis. Performance of the combined approach was compared to conventional liquid-liquid extraction (EPA Method 3510C) across diverse water matrices, including reagent water, wastewater, and groundwater.

Methodology and Instrumentation

Extraction: Samples (500 mL) were spiked with surrogate standards, capped with SPE-compatible lids, and processed on the SPE-DEX® automated platform using DVB extraction disks (Speed Disk #8067-06). The protocol automates disk pre-wetting, sample loading, solvent elution (approx. 12–15 mL extract), and drying with sodium sulfate.

• Instrument: SPE-DEX automated extractor (Horizon Technology).
• Disk sorbent: Divinylbenzene (Speed Disk #8067-06, J.T. Baker).

Injection: The extract is adjusted to 30 mL, and 1 mL aliquots are transferred to GC vials with internal standards. A 30 μL volume is introduced via a programmable temperature vaporization injector operated in cold splitless mode with solvent elimination and rapid thermal ramping.

• Gas chromatograph: Agilent 6890 GC with ATAS OPTIC2 PTV injector.
• Mass spectrometer: Agilent 5973 MSD.
• Column: 30 m × 0.25 mm Rtx-5, 0.50 μm film.

Key Results and Discussion

In clean reagent water, SPE-LVI and liquid-liquid extraction delivered comparable recoveries. However, environmental matrices highlighted superior performance of the automated SPE/PTV approach:

• Analyst time reduced by ≥75%, enabling throughput increase from 8–12 to over 50 samples/day.
• Solvent consumption decreased from >200 mL to ~30 mL per sample, lowering costs and waste.
• Analyte recoveries and precision improved, particularly for volatile semivolatiles prone to loss during concentration.
• Method detection limits met regulatory requirements with 30 μL injections, supporting 100 ppb spiking and higher recoveries across wastewater, groundwater, and river water samples.

Recovery of highly polar compounds such as phenol remained lower on DVB disks, suggesting alternative sorbents may optimize extraction for polar analytes.

Benefits and Practical Applications

• Streamlined workflow eliminates manual post-extraction concentration, reducing error sources and labor.
• Enhanced throughput and reproducibility are ideal for high-volume environmental and QA/QC laboratories.
• Lower solvent usage and waste disposal requirements improve safety and sustainability.
• Flexible injection volumes via PTV allow compliance with stringent detection limits without additional concentration steps.

Future Trends and Potential Applications

• Development of sorbents tailored for polar semivolatiles to broaden analyte coverage.
• Integration of online SPE-LVI systems for fully automated end-to-end analysis.
• Application to emerging contaminants in complex matrices.
• Coupling with high-resolution MS for enhanced identification and quantitation in environmental monitoring.

Conclusion

Combining automated SPE with large-volume PTV injection represents a significant advance in environmental semivolatile analysis under EPA Method 8270D. The approach simplifies sample preparation, lowers costs, improves analytical performance, and supports high-throughput laboratory operations. Continued optimization of sorbents and instrumentation integration will further expand its utility for complex analytes and matrices.