Brominated Flame Retardant in PET

Significance of the Topic

Brominated flame retardants such as TBBPA, PBDEs and PBBs are widely used in electronic plastics and raise environmental and health concerns due to their persistence and bioaccumulation. Regulatory frameworks like RoHS and WEEE in the EU drive the need for accurate monitoring of these compounds directly in polymer matrices.

Objectives and Study Overview

This application note illustrates a rapid thermal sampling method coupled with GC/MS to detect brominated flame retardants in poly(ethylene terephthalate) (PET). A small PET sample containing flame retardants was analyzed to evaluate direct solid analysis performance.

Methodology

The approach employs a pyroprobe autosampler to heat the PET sample at 400°C for 15 seconds, releasing brominated compounds for GC/MS analysis. Key steps include:

• Thermal desorption of the polymer to liberate flame retardants
• Chromatographic separation on a 5% phenyl GC column with helium carrier gas
• Mass spectrometric detection scanning m/z 35–550, with targeted monitoring at m/z 486 for tetrabromo diphenyl ether

Instrumentation

• Pyroprobe Autosampler with coil interface
• Gas Chromatograph equipped with a 5% phenyl (30 m × 0.25 mm) column
• Mass Spectrometer scanning m/z 35–550
• Operational parameters:
  • Pyrolysis: 400°C for 15 s
  • Valve oven: 300°C
  • Injector: 350°C
  • Oven program: 40°C for 2 min, then 10°C/min to 300°C

Main Results and Discussion

The total ion chromatogram and extracted ion chromatogram at m/z 486 reveal a distinct peak at roughly 23 minutes, corresponding to tetrabromo diphenyl ether. The mass spectrum displays characteristic bromine isotope cluster patterns with fragments bearing one to four bromine atoms, confirming the presence of brominated flame retardants directly desorbed from PET.

Benefits and Practical Applications

• Direct analysis of solid plastic without complex sample preparation
• Rapid screening for regulatory compliance (RoHS/WEEE)
• High selectivity and sensitivity via targeted mass detection

Future Trends and Applications

• Integration of high-resolution mass spectrometry for improved compound identification
• Extension to diverse polymer types and emerging flame retardant chemistries
• Automation and miniaturization of thermal sampling for routine QA/QC
• Screening non-halogenated and novel flame retardants

Conclusion

Pyrolysis-GC/MS offers a fast, reliable route for direct determination of brominated flame retardants in PET, supporting environmental monitoring and regulatory compliance with minimal preparation.