Simple quantitative analysis of a brominated flame retardant in polystyrene by thermal desorption GC/MS < study using an AIST RoHS certified standard >

Significance of the topic

Brominated flame retardants such as decabromodiphenylether (DeBDE) are widely used in electronic devices but are restricted under the RoHS directive due to their toxicity and persistence. Accurate quantification of these compounds in polymer matrices is essential for compliance monitoring and environmental safety. This technical note demonstrates a streamlined thermal desorption GC/MS method that accommodates the thermolabile nature of DeBDE, providing rapid and reliable analysis in polystyrene samples.

Objectives and Study Overview

The primary aim was to evaluate the feasibility of a simple quantification protocol for DeBDE in polystyrene using thermal desorption GC/MS. An AIST RoHS certified standard containing 317 ppm DeBDE and spiked PS samples (200–1000 ppm) were analyzed to construct a calibration curve and to verify accuracy against the certified value.

Methodology and Instrumentation

Samples were prepared by depositing 20 µL of PS solution (25 µg/µL in xylene/DCM 10:90) into pyrolyzer cups and evaporating the solvent. Thermal desorption was performed from 200 to 340 °C to release DeBDE while minimizing polymer pyrolysate interference. Key instrument parameters:

• Pyrolyzer furnace ramp: 100–600 °C at 10 °C/min
• Thermal desorption: 200–300 °C at 40 °C/min, then to 340 °C at 5 °C/min
• GC oven: 80–300 °C at 20 °C/min
• Column: Ultra ALLOY-PBDE (15 m×0.25 mm i.d., 0.05 µm)
• Carrier gas: He at 1 mL/min, split 1:20
• Detection: GC/MS in TIC and SIM mode (m/z 799)

Main Results and Discussion

DeBDE evolved primarily between 250 and 400 °C, with 340 °C selected as the upper desorption temperature to limit background from PS pyrolysis. Quantitation based on TIC peak area yielded an average concentration of 347 ppm (n=5, RSD 6.1 %), which is within 10 % of the certified 317 ppm. The EGA thermogram and SIM chromatograms confirmed selective detection of DeBDE.

Benefits and Practical Applications

This method offers:

• Minimal sample preparation and rapid analysis
• High selectivity for thermolabile flame retardants
• Compliance assessment for RoHS-regulated materials
• Applicability to polymer screening in electronics and environmental monitoring

Future Trends and Possibilities

Advancements may include coupling with high-resolution MS for improved sensitivity, automated sample introduction systems for higher throughput, expansion to other halogenated compounds, and integration with chemometric tools for complex matrix analysis.

Conclusion

The described thermal desorption GC/MS procedure provides a straightforward, accurate, and reproducible approach for quantifying DeBDE in polystyrene, aligning well with regulatory requirements and offering a valuable tool for routine quality control.

References

• T. Yuzawa et al., Analytical Sciences, 24 (2008) 953