Extraction of Phthalates and Adipates from Water, Using Solid Phase Extraction Disks

Significance of the Topic

Phthalates and adipates are widely used plasticizers that can leach into water sources and pose environmental and human health concerns. Reliable trace-level monitoring in aqueous matrices is essential for regulatory compliance, quality assurance, and risk assessment. Solid phase extraction (SPE) disks offer a streamlined sample preparation approach to isolate these semivolatile contaminants from large water volumes with minimal solvent use and rapid processing.

Objectives and Study Overview

This application note describes an SPE-based workflow to extract phthalates and adipates from one-liter water samples following the principles of US EPA Method 506. Key goals include demonstrating disk conditioning, sample loading, analyte elution, cleanup, and compatibility with GC-based detection methods for routine laboratory analysis.

Methodology and Used Instrumentation

The extraction sequence consists of:

• Disk conditioning with methanol and deionized water under low vacuum to activate the C18-modified glass fiber disk surface without introducing air pores.
• Sample addition by allowing a 1 L water sample, spiked if needed for QC/QA, to gravity-feed onto the disk, followed by controlled vacuum (≈100 mL/min) to maintain wetting.
• Analyte elution using sequential rinses: acetonitrile (twice) and methylene chloride (twice), collecting all eluates in a single tube.
• Cleanup by passing the combined eluate through anhydrous sodium sulfate to remove residual water.
• Concentration to 1 mL under gentle evaporation for injection (1–2 µL) into GC/PID or GC/MS systems according to EPA Method 506 protocols.

Instrumentation:

• ENVI-Disk SPE apparatus with vacuum flask, reservoir, and filtration support.
• Gas chromatograph equipped with photoionization detector or mass spectrometer.
• Analytical balance and nitrogen evaporator (for concentration).

Main Results and Discussion

The described SPE disk method achieves rapid sample throughput (>100 mL/min) and minimized clogging compared to Teflon® disks. Solvent volumes are kept low (≈25 mL total), and disk rigidity ensures reproducible recoveries of target phthalates and adipates. The approach aligns with EPA performance requirements, delivering clean extracts suitable for sensitive GC analysis.

Benefits and Practical Applications

• Efficient processing of large water volumes with high flow rates and minimal downtime.
• Reduced solvent consumption and waste generation relative to cartridge-based SPE.
• Scalable to routine QA/QC testing in environmental, industrial, and municipal laboratories.

Future Trends and Opportunities

Advancements may include alternative sorbent chemistries for broader analyte ranges, on-disk derivatization for improved detection, and integration with automated SPE systems. The methodology can be adapted for emerging contaminants in diverse water matrices, including wastewater and groundwater.

Conclusion

The ENVI-Disk SPE protocol provides a robust, cost-effective solution for extracting phthalates and adipates from water samples. Its compatibility with established EPA workflows and GC-based detection ensures reliable quantitation for environmental monitoring and regulatory compliance.

References

• US Environmental Protection Agency Method 506