GC-APCI-QTOF MS for Detection of PCBs and PCDDs: Classic innovation to meet today's trace detection and target quantitation requirements

Significance of the Topic

Persistent organic pollutants such as dioxin-like PCBs and PCDDs/PCDFs pose critical health and regulatory challenges due to their toxicity and persistence in environmental and food matrices. Achieving reliable trace-level detection and quantitation is essential for compliance with stringent governmental regulations and for ensuring public safety.

Objectives and Study Overview

This study evaluates the performance of a GC-APCI-QTOF MS workflow against US EPA Method 1613B criteria. Key objectives include demonstrating sensitivity, precision, mass accuracy, and automated confirmation capabilities for targeted analytes in both standard solutions and complex fish tissue extracts.

Methodology and Applied Instrumentation

Samples comprised native and 13C-labelled dioxin-like PCBs and PCDDs/PCDFs in n-nonane and spiked fish tissue prepared by pressurized fluid extraction. Chromatographic separation was performed on a BR-Dioxin2 capillary column with tailored temperature programs for PCBs and PCDDs/PCDFs. The APCI source employed a corona discharge under dry and doped nitrogen conditions to generate molecular ions with minimal in-source fragmentation. The impact II UHR QTOF mass spectrometer acquired alternating full scan and MS/MS data. Automated data processing in Bruker TASQ applied multi-criteria MRSQ scoring based on mass accuracy, retention time, isotopic fidelity, and diagnostic ions.

• Gas Chromatography: Bruker 436 GC, He 1.5 mL/min, splitless injection, 60 m×0.25 mm BR-Dioxin2 column.
• APCI Source: Corona 8000 nA, source 300 °C, drying gas 1.5 L/min at 175 °C.
• QTOF MS: Impact II UHR QTOF in full scan and MS/MS, mass filtering ±3 mDa.

Main Results and Discussion

• Calibration curves exhibited R2>0.998 (PCBs) and >0.997 (PCDDs/PCDFs); response factor RSD<14%.
• Signal-to-noise ≥10 for all analytes at the lowest calibration point; instrumental LOD 50 fg on-column, LOQ 150 fg.
• Precision: RSD<7.3% for PCBs and <12.8% for PCDDs/PCDFs; recoveries 98–115%; resolution >18 000.
• Carry-over assessment showed no detectable residue, minimizing false positives and negatives.
• Fish tissue analysis confirmed simultaneous identification and quantitation of three PCDDs/PCDFs and twelve PCBs meeting EPA criteria.

Benefits and Practical Applications

This GC-APCI-QTOF MS approach delivers high sensitivity and selectivity for non-polar to moderately polar persistent organic pollutants in complex matrices. Preservation of molecular ions and simplified fragmentation patterns support confident compound confirmation and retrospective screening in environmental, food safety, and toxicology laboratories.

Future Trends and Applications

Rapid interchange of APCI and ESI sources without venting will broaden analyte coverage from polar to non-polar compounds. The workflow is poised for expanded use in pesticide residue analysis, food contact material screening, and forensic toxicology. Enhanced software automation will further streamline high-throughput screening and compliance reporting.

Conclusion

GC-APCI-QTOF MS meets or exceeds all US EPA 1613B performance criteria for dioxin-like PCBs and PCDDs/PCDFs in both standard and fish tissue samples. The technique offers robust sensitivity, high mass accuracy, and comprehensive automated QC, making it an outstanding tool for targeted and non-targeted screening of persistent organic pollutants.

References

• EPA Method 1613B Revision B, 1994.
• Dzidic I. et al., Anal Chem, 1976, 48(11):1763-1768.
• Horning EC. et al., Clin Chem, 1977, 23(1):13-21.
• WHO TEF for Dioxins and PCBs, 2005.
• Gómez-Pérez ML. et al., J Am Soc Mass Spectrom, 2014, 25:899-902.
• Mesihää S. et al., Anal Bioanal Chem, 2017, 409:2007-2013.