Dioxins and Furans Analysis

Significance of the Topic

Polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) represent one of the most toxic classes of environmental contaminants. Their persistence, bioaccumulative behavior and adverse effects on human health and ecosystems require monitoring at ultra-trace levels in food, water, soil and biota.

Objectives and Study Overview

This article reviews the transition from traditional high-resolution magnetic sector GC-MS to modern Atmospheric Pressure GC coupled with tandem quadrupole MS (APGC-MS/MS) for dioxin/furan analysis. It highlights regulatory drivers, operational challenges, a multi-year comparative study by SGS AXYS (Method 16130) and recent US EPA interim approval of an APGC-MS/MS protocol.

Methodology and Instrumentation

The established workflow uses standard sample extraction and cleanup procedures followed by gas chromatography. Two mass spectrometric approaches are compared:

• GC-HRMS with electron ionization on a magnetic sector instrument, employing narrow 100 ppm mass windows and isotope dilution calibration with 13C-labeled standards.
• APGC-MS/MS with the Waters Xevo TQ-XS platform, using soft atmospheric pressure chemical ionization (APCI) to generate abundant molecular ions and scheduled multiple reaction monitoring (MRM) transitions for quantitation.

Instrumentation Used

• Waters Atmospheric Pressure GC source (APGC)
• Waters Xevo TQ-XS tandem quadrupole mass spectrometer with StepWave ion guide
• Gas chromatograph with configured columns for PCDD/PCDF separation
• MassLynx software for method control and data analysis
• 13C-labeled dioxin/furan standards from Wellington Laboratories

Main Results and Discussion

APGC-MS/MS delivered superior signal-to-noise ratios and routinely met or exceeded regulatory detection limits (e.g. 0.1 pg injections of 2,3,7,8-TCDD). Comparative trials showed relative percent differences between HRMS and MS/MS well within acceptance criteria. The soft ionization reduced in-source fragmentation, improving sensitivity and selectivity without altering extraction or chromatographic conditions.

Benefits and Practical Applications

Laboratories adopting APGC-MS/MS experience:

• Enhanced sensitivity and precision at ultra-trace levels
• Simplified sample preparation via reduced extract volumes and solvent usage
• Faster instrument turnaround with less frequent maintenance and bench-top footprint
• Streamlined training and operation compared to magnetic sector systems
• Lower overall consumable and operational costs

Future Trends and Opportunities

Broader regulatory acceptance of APGC-MS/MS will drive updates to persistent organic pollutant (POP) testing protocols worldwide. Upcoming advances may include automation in sample cleanup, further soft-ionization refinements, real-time data analytics and extension to other emerging contaminants.

Conclusion

APGC-MS/MS on tandem quadrupole platforms offers a robust, sensitive and cost-effective alternative to magnetic sector HRMS for dioxin and furan analysis. Its regulatory recognition and operational advantages position it as a new standard for routine environmental and food safety laboratories.

References

1. Organtini KL et al. ACS Analytical Chemistry, 2015, DOI:10.1021/acs.analchem.5b01705
2. Jones R et al. ACS Analytical Chemistry, 2015, DOI:10.1021/acs.analchem.5b02264