Quantification Of Decabromodiphenyl Ether In Microplastics Using Direct Insert Probe Coupled With Magnetic Sector High Resolution Mass Spectrometer In Full Scan Mode

Importance of the Topic

The accumulation of microplastics in the environment and their ability to carry persistent organic pollutants (POPs) such as brominated flame retardants (BFRs) have raised significant concerns for human and ecological health. In particular, decabromodiphenyl ether (BDE209) in microplastics demands rapid, sensitive and accurate analytical methods to assess exposure pathways, support regulatory compliance and guide risk management strategies.

Objectives and Study Overview

This study presents a novel approach for direct quantification of BDE209 in microplastic matrices using a Direct Insertion Probe coupled with a magnetic sector high-resolution mass spectrometer (DIP-HRMS). The goals were to develop a sample-preparation-free method, evaluate its performance against conventional GC-MS workflows and demonstrate applicability to real polymeric samples containing variable BDE209 levels.

Methodology and Instrumentation

This method employs:

• Direct Insertion Probe (DIP) introducing ~0.045 mg of polymer sample at room temperature into the ion source under vacuum.
• Thermo Scientific™ DFS™ Magnetic Sector HRMS operating in full-scan electron ionization mode at 20 000 FWHM resolution.
• Optimized temperature ramp and electron energy for maximum sensitivity and controlled fragmentation of BDE209.
• Accurate mass determination of molecular ion (m/z 959) and main fragment (m/z 799) using Xcalibur™ and Mass Frontier™ software.

Main Results and Discussion

Calibration was achieved with five solid reference materials (0–2 % w/w BDE209 in ABS), yielding linearity (R2 > 0.999) over a wide concentration range. The method detection limit (LOD) and quantification limit (LOQ) were 0.112 mg·kg⁻¹ and 1.120 mg·kg⁻¹, respectively. Reproducibility tests showed intraday RSD of 1.96 % and interday RSD of 0.51 %. Comparison with GC-MS indicated that DIP-HRMS avoids thermal degradation and debromination issues, provides a two-fold higher molecular-to-fragment ion ratio, and reduces analysis time by a factor of 50.

When applied to 21 consumer polymer samples, measured BDE209 concentrations (8.8–4327 mg·kg⁻¹) correlated strongly (R2 = 0.86) with total bromine measured by XRF, confirming method validity even in complex matrices.

Benefits and Practical Applications

The DIP-HRMS approach offers:

• Sample-preparation-free quantification directly on small plastic fragments and microplastics.
• High throughput and minimal sample consumption (≈0.045 mg).
• Accurate mass discrimination to distinguish molecular ions from thermal fragments.
• Compatibility with existing polymer reference materials for RoHS compliance testing.

Future Trends and Applications

Further developments may include expansion to lower-brominated diphenyl ethers and other POP congeners, integration with portable mass spectrometers for in-field screening, and automated workflows for high-throughput regulatory monitoring. Enhanced data processing algorithms could also enable rapid isomer differentiation in mixed microplastic samples.

Conclusion

The presented DIP-HRMS method constitutes a rapid, robust and sensitive platform for quantifying BDE209 in microplastics and polymer materials. By eliminating labor-intensive sample preparation and mitigating thermal degradation, it provides a compelling alternative to GC-MS for regulatory and research laboratories.

References

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