Determination of Chlorinated Dioxins and Furans in Four Types of Wastewater by EPA Method 1613 Rev. B

CDS Empore™ C18 SPE Disks provide rapid, reliable sample preparation with excellent analyte recovery for screening and monitoring dioxins and furans in wastewater per EPA Method 1613 Rev. B. Average recovery of native compounds across four wastewater types: 109%.

Authors: Guotao Lu

Introduction

EPA Method 1613 Rev. B was developed for isomer-specific determination of 2,3,7,8-substituted, tetra through octa-chlorinated dibenzo-p-dioxins and dibenzofurans in aqueous, solid, and tissue matrices using isotope dilution HRGC/HRMS.

A key challenge with this method is the requirement for large sample volumes (1 liter) at low pH (pH 2). Many SPE disk products risk losing C18 phase from the silica support under these harsh conditions, which can complicate chromatographic analysis with high background and obscure target compounds.

CDS Empore™ C18 SPE Disks are specifically designed to handle these conditions — maintaining phase integrity at pH 2 across 1-liter sample volumes without degradation.

Key advantage: EPA specifically notes that phase stripping at pH 2 can produce high chromatographic background, obscuring compounds of interest. Empore™ C18 Disks eliminate this risk through their proprietary PTFE membrane structure.

Wastewater Types Tested

Four types of wastewater provided by EPA were evaluated in this study:

1. POTW final effluent — Publicly Owned Treatment Works

2. Petroleum refinery API separator effluent

3. Petroleum refinery secondary treatment effluent

4. River water

All samples were spiked with isotopically labeled analogs of CDDs/CDFs at concentrations ranging from 200 pg/L to 2000 pg/L, with triplicate analysis for each matrix. Validation data were generated across three independent lots of C18 disks.

Extraction Method

The extraction follows EPA Method 1613 Rev. B guidelines using 90mm CDS Empore™ C18 disks. For particulate-free samples, 47mm disks can be used.

1. Sample preparation — Add isotopically labeled analogs, 5 mL methanol, and adjust to pH 2. Allow sediment to settle.

2. Disk prewash — Rinse with 15 mL toluene, soak 1 minute, pull through. Repeat with 15 mL acetone.

3. Conditioning — Pre-wet with 15 mL methanol, soak 1 minute, pull through leaving 3–5 mm on the surface. Do not allow the disk to dry from this point forward.

4. Equilibration — Rinse with two 50 mL aliquots of reagent water.

5. Extraction — Filter 1-liter sample under full vacuum. Particulate-free samples can pass through in as little as 10 minutes.

6. Soxhlet extraction — Transfer disk and prefilter to Soxhlet apparatus, extract 16–24 hours with toluene.

7. Clean-up and analysis — Concentrate and proceed per Method 1613 directions. Detection by isotope dilution HRGC/HRMS.

Critical step: The conditioning step (Step 3) is essential for uniform flow and good recovery. The disk is composed of hydrophobic materials that must be pre-wetted with methanol before aqueous samples. If the disk dries accidentally, simply repeat the pre-wetting step.

Results

The CDS Empore™ C18 disk successfully extracted all 16 targeted dioxins and furans from four types of wastewater. Detailed validation data are shown below.

• Average recovery: 109% for native compounds across all four wastewater matrices

• All recovery rates within 75–125% per EPA Method 1613B acceptance criteria

• Only one compound slightly below 90%: 12378-PeCDD in POTW effluent at 88%

• Only one compound slightly above 120%: 123678-HxCDD in river water at 123%

• All other compounds: 90–120% recovery

• Post-extraction filtrates: "not detected" for all analytes, confirming complete extraction

• All extractions completed in under 20 minutes

Conclusion

This study validates that CDS Empore™ C18 disks deliver excellent recovery and clean chromatograms for dioxin and furan analysis in wastewater per EPA Method 1613 Rev. B. The method handles 1-liter samples at pH 2 without phase degradation, achieving 109% average recovery across four challenging wastewater matrices — all within EPA's 75–125% acceptance criteria.

For laboratories screening or monitoring chlorinated dibenzo-p-dioxins and dibenzofurans in wastewater, CDS Empore™ C18 disks ensure rapid, economical, and reliable sample preparation.

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References

1. Clean Water Act, the Resource Conservation and Recovery Act, the Comprehensive Environmental Response, Compensation and Liability Act, and the Safe Drinking Water Act. Issued October 1994 by US EPA Office of Water.

2. EPA Method 1613, Revision B. Determination of 2,3,7,8-substituted tetra through octa-chlorinated dibenzo-p-dioxins and dibenzofurans by isotope dilution HRGC/HRMS. U.S. Environmental Protection Agency, Cincinnati, OH.