Extraction of Organic Compounds from Water, Using ENVI™-18 DSK Solid Phase Extraction Disks

Significance of Topic

Solid phase extraction (SPE) is a cornerstone technique for isolating trace organic contaminants from environmental waters. ENVI™-18 DSK SPE disks combine a rigid glass fiber support with C18-modified silica, offering high flow rates, reduced clogging, and cost efficiency. This approach supports regulatory compliance (EPA Method 525.1) and accelerates analysis of semivolatiles, pesticides, PCBs and other hydrophobic analytes in drinking and surface waters.

Objectives and Study Overview

This application note outlines a robust protocol to extract a broad spectrum of organic compounds from 1 L water samples using 47 mm ENVI-18 DSK disks. The goals are to demonstrate disk conditioning, sample percolation, analyte elution, and final concentration steps in accordance with EPA Method 525.1, ensuring reproducible recoveries and compatibility with GC/MS analysis.

Methodology

Sample Preparation and Conditioning:

• Equilibrate 1 L water to ambient temperature; adjust pH to <2 with 6 N HCl.
• Add 5 mL methanol and internal standards (e.g., pentachlorophenol, surrogate mix) and mix thoroughly.

Disk Conditioning:

• Rinse disk with 5 mL methanol under low vacuum, then with 5 mL deionized water to maintain wetted surface.

Sample Loading:

• Percolate sample at ~100 mL/min under ~10" Hg vacuum; prevent disk drying until complete.

Disk Drying and Elution:

• Dry disk with air under moderate vacuum (~15" Hg) for 5 min.
• Elute analytes with three 5 mL portions of methylene chloride under low vacuum, collecting combined eluate.

Post-Extraction Cleanup and Concentration:

• Remove residual water using anhydrous Na2SO4.
• Concentrate eluate to 1 mL and analyze 1 µL by GC/MS per EPA Method 525.1.

Used Instrumentation

• ENVI-18 DSK SPE disks (47 mm, C18 bonded silica on glass fiber).
• Vacuum manifold and 1 L glass flask assembly.
• Methylene chloride, methanol, sodium sulfate (anhydrous).
• Gas chromatograph–mass spectrometer configured per EPA 525.1.

Main Results and Discussion

ENVI-18 DSK disks delivered rapid flow rates (~100 mL/min) and consistent retention of semivolatiles, PCBs, pesticides and phthalates. The glass fiber support minimized particulate clogging compared to Teflon disks. Reproducible recoveries met EPA quality criteria, and the protocol achieved efficient removal of matrix water prior to GC/MS, ensuring low detection limits and accurate quantitation.

Benefits and Practical Applications of the Method

• High throughput extraction of large-volume water samples with minimal maintenance.
• Broad analyte compatibility, including PAHs, PCBs, pesticides and phthalates.
• Cost savings through reusable manifold components and durable disks.
• Streamlined integration with GC/MS workflows for environmental monitoring and regulatory compliance.

Future Trends and Potential Applications

Future developments may include automation of disk conditioning and elution, miniaturization for on-site analysis, and adaptation to emerging contaminants such as per- and polyfluoroalkyl substances (PFAS). Green solvents and novel sorbent chemistries are under exploration to further reduce environmental impact and enhance selectivity.

Conclusion

ENVI-18 DSK SPE disks provide a reliable, rapid and cost-effective platform for extracting trace organic contaminants from water. Their compatibility with EPA Method 525.1 and high reproducibility make them well suited for routine environmental analysis, research applications and QA/QC programs.

References

• US Environmental Protection Agency Method 525.1, National Technical Information Service, U.S. Department of Commerce, Springfield, VA, 22161, USA.