Analysis of PBDEs in Sediment Using GC-MS/MS

Importance of the Topic

Sediments often accumulate polybrominated diphenyl ethers (PBDEs), a class of brominated flame retardants widely used in plastics. Due to their persistence, bioaccumulation potential and toxicity, PBDEs are regulated under the Stockholm Convention, creating demand for reliable analytical methods to monitor environmental contamination.

Study Objectives and Overview

This work evaluates gas chromatography coupled with single-quadrupole mass spectrometry (GC-MS) and tandem mass spectrometry (GC-MS/MS) for quantification of eight PBDE congeners in sediment samples. The goal is to compare selectivity, sensitivity and robustness of SIM (selected ion monitoring) and MRM (multiple reaction monitoring) modes during analysis of complex matrices.

Methodology and Instrumentation

Target and isotopically labelled surrogate standards were used to prepare calibration solutions ranging from 10 to 500 ng/mL (100–5000 ng/mL for deca-BDE). Sediment samples were spiked with surrogates, extracted via Soxhlet, and subjected to a multi-step cleanup including sulfuric acid treatment, sulfur removal with copper powder, and Florisil column adsorption.

Instrumentation Used

• GC-MS: Shimadzu GCMS-QP2010 Ultra in SIM mode
• GC-MS/MS: Shimadzu GCMS-TQ8030 in MRM mode
• Column: Rtx-1614, 30 m length, 0.25 mm I.D., 0.1 µm film
• Injection: Splitless at 320 °C, 1 µL volume
• Oven program: 140 °C (3 min)→5 °C/min→320 °C (5 min)
• Carrier: Linear velocity 47.9 cm/s, high-pressure injection at 150 kPa for 1.2 min
• MS parameters: Interface 300 °C, ion source 230 °C, high-sensitivity tuning

Key Results and Discussion

Calibration curves for the eight target PBDE congeners demonstrated excellent linearity (r≥0.9999) over the tested range. MRM chromatograms yielded clear, interference-free signals for all congeners at 10 ng/mL, while SIM mode suffered from co-extracted matrix interferences that obscured some PBDE peaks. The enhanced selectivity of MRM allowed reliable quantitation in complex sediment extracts.

Benefits and Practical Applications

• High selectivity of MRM enables detection of low-level PBDEs in challenging environmental matrices
• Linear response over wide concentration ranges supports regulatory compliance and monitoring
• Robust sample preparation workflow reduces matrix effects and improves reproducibility

Future Trends and Opportunities

Advances in high-resolution mass spectrometry and automated sample cleanup may further enhance sensitivity and throughput. Integration of multi-analyte screening methods and miniaturized extraction techniques could expand monitoring capabilities for diverse persistent pollutants in sediments and biota.

Conclusion

GC-MS/MS in MRM mode offers a robust, selective and sensitive approach for quantifying PBDE congeners in sediment samples. Compared to SIM, MRM minimizes matrix interferences and provides linear, reproducible results, making it the preferred technique for environmental monitoring of brominated flame retardants.

References

1. Shimadzu Application Note LAAN-J-MS-E063a, Shimadzu Corporation, First Edition May 2012; Second Edition July 2012.