Simplifying Persistent Issues with Dioxins Analysis in the Environment using GC/MS/MS

Importance of the Topic

The accurate determination of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in environmental matrices is essential for monitoring toxic pollutants and ensuring compliance with regulatory limits. Traditional high-resolution magnetic sector GC/MS methods are sensitive but expensive and complex. The adoption of triple quadrupole GC/MS offers a cost-effective alternative while maintaining required selectivity and sensitivity.

Objectives and Overview

This work describes the development and validation of an alternative testing protocol (ATP) aligned with U.S. EPA Method 1613B for the analysis of dioxins and furans using an Agilent 8890 GC coupled to a 7010B triple quadrupole mass spectrometer (GC/TQ). Key goals include demonstrating chromatographic resolution, instrument stability, method performance across different sample types, and comparability to high-resolution GC/MS.

Methods and Instrumentation

Sample Preparation:

• Followed the sample cleanup procedures of EPA 1613B for aqueous, solid, biosolid, and tissue extracts.
• Applied performance-based cleanup using multi-stage column separations (silica, alumina, florisil or carbon) to remove interferences and optimize signal-to-noise.

Instrumentation:

• Agilent 8890 GC with splitless inlet and a 60 m × 0.25 mm × 0.10 µm (5%-Phenyl)-methylpolysiloxane column.
• Agilent 7010B triple quadrupole MS equipped with Reference Compound Introduction Valve (RCIV) to infuse perfluorotributylamine (PFTBA) as an internal performance monitor.
• Injection volume: 1 µL; splitless, double-taper, deactivated liner.

Main Results and Discussion

Chromatography and Resolution:

• Achieved clear resolution of 17 toxic PCDD/PCDF congeners, meeting EPA 1613B valley-height criteria for 2,3,7,8-TCDD and TCDF isomers (< 25% valley height).

Instrument Stability:

• PFTBA infusion via RCIV provided a stable reference signal throughout multi-hour runs, enabling real-time monitoring of transmission efficiency without user intervention.

Performance Metrics:

• Mean recoveries across aqueous, solid, and tissue matrices ranged within EPA Method 1613B acceptance criteria with relative standard deviations below target levels.
• Method detection limits (MDLs) for each congener met or exceeded EPA MRL requirements.
• Comparison of total PCDD/PCDF concentrations in biosolid samples showed strong agreement between GC/TQ and high-resolution GC/MS analyses.

Benefits and Practical Applications

The Agilent 7010B GC/TQ approach delivers:

• Lower acquisition and operational costs compared to high-resolution systems.
• Reduced instrument complexity and maintenance burden.
• High data quality and regulatory compliance for routine environmental and industrial analyses.

Future Trends and Potential Applications

Emerging developments may include:

• Integration of automated sample preparation workflows to increase throughput.
• Expansion of triple quadrupole applications to other regulated semivolatile organic compounds.
• Enhanced software algorithms for real-time performance tracking and data validation.
• Broader acceptance of GC/TQ methods in official regulatory compendia globally.

Conclusion

This study demonstrates that triple quadrupole GC/MS, when configured and validated according to an ATP for EPA Method 1613B, can provide robust, sensitive, and cost-effective analysis of dioxins and furans in complex environmental matrices. The methodology meets regulatory criteria and offers a practical alternative to high-resolution techniques.

Použitá instrumentace

• Agilent 8890 Gas Chromatograph with splitless inlet.
• 60 m × 0.25 mm × 0.10 µm (5%-Phenyl)-methylpolysiloxane capillary column.
• Agilent 7010B Triple Quadrupole Mass Spectrometer with Reference Compound Introduction Valve (RCIV).
• Perfluorotributylamine (PFTBA) as reference compound.

Reference

1. U.S. EPA. Methods for Measurement of 2,3,7,8-Substituted Tetra through Octa-Chlorinated Dibenzo-p-dioxins and Dibenzofurans in Wastewater. March 2021.
2. U.S. EPA. Method 1613: Tetra-Through Octa-Chlorinated Dioxins and Furans by Isotope Dilution HRGC/HRMS. September 1994.
3. Hamilton C., Xie X., Anumol T., Andrianova A., Walker D. An Alternate Testing Protocol for EPA 1613B using Agilent Triple Quadrupole GC/MS. Agilent Technologies Application Note 5994-3029EN, 2022.