Confirmation of PCDDs and PCDFs at Sub-Femtogram Levels Using Atmospheric Pressure Gas Chromatography (APGC) with Xevo TQ-XS

Importance of the topic

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are persistent organic pollutants regulated by the Stockholm Convention due to their toxicity and bioaccumulation. Monitoring these compounds at ultra-trace levels in environmental and food matrices is critical for public health and regulatory compliance. Traditional magnetic sector GC-MS systems achieve necessary sensitivity but require extensive expertise and laborious sample preparation. A more user-friendly yet highly sensitive analytical platform can streamline workflows, reduce costs, and broaden accessibility for routine testing.

Objectives and overview of the study/article

This work demonstrates the performance of an Atmospheric Pressure Gas Chromatography (APGC) source coupled to the Waters Xevo TQ-XS tandem quadrupole mass spectrometer for detecting, confirming, and quantifying PCDDs and PCDFs at sub-femtogram levels. Key aims include evaluating detection limits, linearity, precision, isotopic ratio stability, and applicability to a complex QC fly ash sample under regulatory criteria.

Methodology and instrumentation

• Chromatographic separation on an Agilent 7890A GC with two column setups:
  • 30 m × 0.25 mm ID, 0.25 μm DB-5MS column for targeted 2,3,7,8-TCDD assessment.
  • 60 m × 0.25 mm ID, 0.25 μm ZB-5MS column for comprehensive PCDD/PCDF analysis.
• GC conditions: Helium carrier at 1–1.4 mL/min, pulsed splitless injection (32–50 psi), 1 µL injection volume, customized oven temperature programs.
• Mass spectrometry on Waters Xevo TQ-XS with APGC source: corona pin 2 µA, cone gas 260 L/hr, auxiliary gas 200 L/hr, makeup gas 300 mL/min. MRM transitions monitored with 0.7 Da resolution.
• Standards and samples: Calibration from 100 ag to 100 pg on-column for TCDD; EPA 1613 standard mixtures (CSL–CS5) diluted 1:10 in nonane; QC fly ash for complex matrix evaluation.

Main results and discussion

• Sensitivity and linearity: Achieved excellent linearity for 2,3,7,8-TCDD across seven orders of magnitude (100 ag–100 pg), confirming reliable quantitation at sub-femtogram levels.
• Precision: Twenty-day injection series of 100 fg TCDD (1000 injections) yielded an RSD of 9.2% without internal standard correction, demonstrating outstanding reproducibility.
• Isotopic ratio stability: Consistent isotope ratios (<15% deviation) were maintained across the calibration range and repeat injections, meeting EU and EPA confirmation requirements.
• Complex matrix analysis: The method successfully identified and quantified 2,3,7,8-TCDD in a QC fly ash sample, with measured values aligning closely to certified reference data, showcasing robustness in challenging samples.

Benefits and practical applications

• Ultrasensitive detection reduces the need for extensive sample pre-concentration, lowering analysis time and solvent consumption.
• Dilution of expensive dioxin standards is feasible due to the method’s sub-femtogram sensitivity, minimizing per-sample cost.
• High throughput and robustness support thousands of injections with consistent performance, ideal for environmental, food safety, and QA/QC laboratories.

Future trends and potential applications

• Integration of APGC-MS/MS with automated sample preparation to further increase laboratory efficiency.
• Application of APGC-based methods to other persistent organic pollutants and emerging contaminants.
• Development of hybrid high-resolution tandem MS workflows for combined ultra-trace quantitation and structural elucidation.
• Implementation in large-scale biomonitoring and regulatory compliance programs to address environmental and health risk assessments.

Conclusion

The APGC–Xevo TQ-XS platform represents a significant advancement in the analysis of dioxins and furans, achieving sub-femtogram detection limits, excellent reproducibility, and reliable isotopic confirmation. This system surpasses regulatory requirements while simplifying routine workflows, positioning it as a powerful tool for laboratories committed to accurate and efficient monitoring of persistent organic pollutants.

Reference

• United Nations. Stockholm Convention on Persistent Organic Pollutants, 2001.
• Dunstan J, Hall K, Douce D, Dunstan J, Rosnack K, Ladak A. Confirmatory Method for PCDDs and PCDFs in Compliance with EU Regulation 589/2014/EU Using APGC with Xevo TQ-S. Waters Application Note 720005431en, 2015.
• European Committee for Standardization. EN 16215:2012. Methods for analysis of dioxins and PCBs, 2012.
• EU Commission Regulation 589/2014. Sampling and analysis for dioxins and PCBs in foodstuffs, 2014.
• US Environmental Protection Agency. Method 1613 Revision B: Tetra- through Octa-chlorinated PCDDs and PCDFs, 1994.