Extraction of a Full Suite of Semivolatile Compounds from Drinking Water Using Automated Solid Phase Extraction

Importance of the Topic

Environmental monitoring of semivolatile organic compounds in drinking water is critical due to their potential toxicity, persistence, and widespread use in agriculture, industry, and consumer products. Compounds such as polycyclic aromatic hydrocarbons, nitrotoluenes, legacy pesticides, and phthalates can pose chronic health risks even at low concentrations. Reliable, high-throughput sample preparation and analysis are essential to ensure compliance with regulatory standards, protect public health, and identify pollution sources.

Objectives and Study Overview

This study evaluated an automated solid phase extraction (SPE) workflow for isolating a comprehensive suite of semivolatile analytes from drinking water under US EPA Method 525.2 guidelines. The performance, recovery, and precision of more than 100 target compounds were assessed at a 5 µg/L spike level using the Biotage Horizon 5000 SPE-DEX® 5000 and high-capacity C18 disks. Six replicate fortified blank samples demonstrated accuracy and repeatability.

Methodology and Instrumentation

Each 1 L sample was dechlorinated, acidified to pH <2, and spiked with surrogate and internal standards. Disks were conditioned with methylene chloride, ethyl acetate, methanol, and reagent water before sample loading at 2 mL/min. After loading, disks were air-dried, and analytes were eluted with ethyl acetate and methylene chloride. Extracts were concentrated to 0.9 mL using a DryVap® automated system and prepared for GC/MS analysis.

Instrumentation Used

• Biotage Horizon 5000 SPE-DEX® 5000 Automated Extractor
• DryVap® Automated Drying and Concentration System
• DryDisk® Separation Membranes and Fast Flow Pre-Filters (47 mm, 90 mm)
• Atlantic® C18 High Capacity Disks (47 mm)
• Agilent 6890 GC coupled to 5973 MSD with ZB Semi-Volatiles column (30 m×0.35 mm, 0.25 µm)

Main Results and Discussion

Recoveries for the >100 analytes ranged from 85–127% with an average of 98.8% at 5 µg/L. Precision was excellent, with relative standard deviations typically between 2–3%. All results met the method criteria of 70–130% recovery and <30% RSD. Even water-soluble analytes such as caffeine and nitrophenols were retained effectively. The automated workflow provided consistent, hands-off processing suitable for routine monitoring.

Benefits and Practical Applications of the Method

• Fully automated SPE minimizes manual handling, contamination risk, and operator variability.
• High-capacity C18 disks cover a broad polarity range for comprehensive analyte isolation.
• The combined SPE-DEX 5000 and DryVap system yields reproducible extract volumes ideal for regulatory labs.
• Adaptable to LIMS integration and high-throughput environments, supporting QA/QC in drinking water analysis.

Future Trends and Possibilities for Use

Automation is expected to incorporate multi-disk plate formats, online coupling to chromatographic systems, and expansion into non-targeted screening with high-resolution mass spectrometry. Miniaturization, green solvent alternatives, and AI-driven method optimization may further enhance sensitivity, sustainability, and laboratory efficiency.

Conclusion

The Biotage Horizon 5000 automated SPE workflow, combined with high-capacity C18 disks and DryVap concentration, delivers robust, precise recovery of a full suite of semivolatile compounds from drinking water in compliance with US EPA 525.2. This high-throughput solution supports environmental monitoring and regulatory compliance.

References

• US EPA Method 525.2. Determination of Organic Compounds in Drinking Water by Liquid–Solid Extraction and Capillary Column Gas Chromatography/Mass Spectrometry, 1995.
• US EPA Method 1664B. Oil and Grease and Nonvolatile Material by Extraction and Gravimetry.
• ISO 11349. Water Quality—Oil and Grease—Gravimetric Determination, 2007.
• APHA Standard Methods 5520G. Gas Chromatographic Determination of Oil and Grease.
• Biotage Application Note AN114-HOR.V.1. Extraction of Semivolatiles Using Automated SPE®, 2019.