Improvements to the Analysis of PBDEs in Environmental Matrices: Transitioning from EI Magnetic Sector to GC-APCI TQ MS/MS

Significance of the topic

The legacy flame retardants polybrominated diphenyl ethers (PBDEs) remain an important class of persistent, bioaccumulative and toxic contaminants monitored in environmental matrices. Reliable analytical methods are required to support regulatory compliance and exposure assessment after global production restrictions. Modernizing PBDE analysis to more robust, accessible and flexible platforms reduces dependency on scarce consumables and large magnetic-sector instruments while maintaining or improving sensitivity and selectivity.

Objectives and study overview

This study evaluated the transition from traditional electron ionization (EI) high-resolution magnetic-sector GC-HRMS methods for PBDEs to a gas chromatography — atmospheric pressure chemical ionization triple-quadrupole tandem mass spectrometry (GC-APCI TQ MS/MS) workflow using nitrogen carrier gas. Key aims were to: demonstrate comparable chromatographic resolution and runtime using N2 instead of He, establish MS/MS acquisition strategies that deliver the required sensitivity and specificity, and assess quantitative performance (linearity, precision, accuracy) versus reference method criteria.

Methodology

Sample preparation and standard/QC preparation were performed at the Quebec Laboratory for Environmental Testing with aliquots analyzed at Waters’ laboratory. The chromatographic approach used an Rtx-1614 column (15 m x 0.25 mm, 0.10 µm) with an Agilent 8890 GC and a temperature program producing a total runtime of ~27 minutes. Carrier gas strategy substituted helium with nitrogen and applied a programmed flow ramp to maintain chromatographic resolution and comparable retention times while allowing higher flow rates to lower elution temperatures and reduce on-column degradation of high-brominated PBDEs (notably BDE 209). Mass spectrometric detection employed APGC/APCI positive ion charge exchange ionization in a Xevo TQ Absolute mass spectrometer configured for up to six MRM transitions per analyte. Data processing used waters_connect for Quantitation, including summed MRM reporting to improve signal-to-noise for low-level measurements.

Instrumentation used

• MS: Xevo TQ Absolute (triple quadrupole) with APGC/APCI positive ion charge exchange.
• Ion source/settings: corona pin 1.0 µA; source temperature 150 °C; cone gas 260 L/hr; auxiliary gas 200 L/hr; makeup gas 350 L/hr.
• GC: Agilent 8890; Column: Rtx-1614, 15 m × 0.25 mm × 0.10 µm film.
• Injection: 1 µL @ 260 °C, pulsed splitless at 20 psi for 1.2 min.
• Carrier gas: Nitrogen with programmed flow ramping up to ~4.1 mL/min to achieve the targeted retention and elution profile.

Main results and discussion

• Chromatography: Nitrogen carrier gas with flow ramping reproduced the chromatographic resolution of critical PBDE isomer pairs without scaling column dimensions. BDE 209 eluted earlier with N2 (21.8 min) compared with the He-based reference (24.7 min), with improved peak symmetry and reduced risk of on-column thermal degradation.
• Acquisition strategy: Using up to six MRMs per analyte accounted for multiple naturally occurring isotopic precursor masses and increased method robustness across matrices and sample preparations.
• Quantification and sensitivity: Summing MRMs in waters_connect improved signal-to-noise for measurements near detection limits. Calibration across more than three orders of magnitude yielded average r2 > 0.999 for all analytes.
• Precision and accuracy: Labeled recovery standards showed average %RSD < 10%, and six labeled internal standards averaged %RSD < 3%. High, mid and low QCs (n=3) met precision criteria (within 15% RSD; method limit 20%); after excluding certain outliers (BDEs 196, 197, 206, 207), precision was <10% for all. Calculated QC concentrations met accuracy limits of 70–130% except for some low-level injections for BDEs 196, 197 and 207.
• Operational compatibility: The nitrogen carrier flow required (up to ~4.1 mL/min) is incompatible with conventional EI GC-MS but is acceptable in the GC-APCI TQ configuration used here.

Benefits and practical applications of the method

• Supply resilience: Replacing helium with nitrogen mitigates impacts from He supply instability and cost volatility while preserving chromatographic performance via flow ramping.
• Instrument accessibility: GC-APCI TQ MS/MS is more widely available and less operationally burdensome than magnetic-sector HRMS, offering laboratories a practical, high-throughput alternative for routine monitoring.
• Analytical performance: The method met or exceeded key performance metrics (linearity, precision, accuracy) necessary for regulatory monitoring of PBDEs in environmental matrices.
• Expanded capability: Faster acquisition rates of triple-quadrupole instruments and the multi-MRM approach permit potential consolidation of PBDE analysis with other halogenated flame retardants, including emerging ‘regrettable replacements’, without compromising analytical quality.

Future trends and applications

• Consolidated monitoring panels: With demonstrated performance, GC-APCI TQ workflows can be expanded to include a broader range of brominated and chlorinated flame retardants, enabling more comprehensive screening using a single instrument platform.
• Method harmonization: Adoption of nitrogen carrier strategies and summed-MRM quantitation could be standardized to reduce inter-laboratory variability and dependence on scarce gases.
• Automation and high-throughput screening: The robust TQ acquisition speed supports higher sample throughput and integration with automated sample preparation for large monitoring programs.
• Targeted improvements: Addressing robustness for specific congeners (e.g., BDEs 196, 197, 206, 207) through targeted optimization of transitions or sample prep will further strengthen method performance at low concentrations.

Conclusion

This study demonstrates that an all-nitrogen GC-APCI TQ MS/MS workflow can achieve analytical performance comparable to traditional EI magnetic-sector GC-HRMS methods for PBDEs, while delivering operational advantages in gas supply resilience, instrument accessibility and the potential for broader analyte panels. The combination of flow-ramped N2 chromatography, multiple MRMs per analyte and summed-MRM quantitation provides a sensitive, precise and accurate platform suitable for routine environmental monitoring and regulatory compliance testing. Remaining challenges are analyte-specific low-level behavior for some congeners, which can be addressed by further method refinement.

References

1. Canada Chemicals Management Plan. Polybrominated diphenyl ethers (PBDEs). Government of Canada (Health Canada), Last modified 25 Feb 2026.
2. Stockholm Convention on Persistent Organic Pollutants. United Nations Environment Programme, accessed 30 April 2026.
3. Jennings, K. R. Gas chromatography: Elution temperature, speed of analysis, and separation efficiency as influenced by rate of temperature programming and carrier gas velocity in open tubular capillary columns. Analytical Biochemistry (1975).