ANALYSIS OF A RANGE OF POLYMERS BY AUTOMATED PYROLYSIS GC-MS USING THE GERSTEL PYRO

Importance of the Topic

Microplastics and polymer debris present increasing environmental and health challenges due to widespread use of single-use plastics. Accurate and rapid identification of polymer types, even at trace levels, is essential for environmental monitoring, industrial quality control, and research into plastic degradation.

Objectives and Study Overview

This work demonstrates the application of automated pyrolysis GC-MS using a GERSTEL pyrolysis module to characterize a variety of polymer types. Standard polymers and unknown samples from the University of Birmingham were analyzed to evaluate the method’s ability to identify individual and mixed polymeric materials.

Methodology and Instrumentation

Small aliquots (<1 mg) of polymer were placed in pyrolysis sample tubes and introduced into a Thermo Desorption Unit (TDU) and pyrolysis module via a GERSTEL MPS robotic sampler. The TDU was ramped from 50 °C to 300 °C, and the pyrolysis module heated to 600 °C to generate volatile degradation products. The GC-MS system comprised an Agilent 7890A GC coupled to a 7000 MS, fitted with a DB-5MS column (30 m×0.32 mm×0.25 µm). The oven program held at 50 °C, ramped at 10 °C/min to 320 °C, with MS detection in scan mode (m/z 10–550).

Results and Discussion

Characteristic pyrograms were obtained for standards:

• HDPE: peaks reflecting alkene chain fragments and unsaturation.
• PET: vinyl benzoate, benzoic acid, divinyl terephthalate.
• PS/EPS: toluene, styrene, methyl styrene.
• Nylon 6: caprolactam.
• PP: alkene repeats and unsaturation markers.
• PMMA: methyl methacrylate.

Unknown samples (blue rope and pink string) matched PP and PET profiles, respectively. Binary mixtures of EPS/PP and PS/PP showed discernible peaks for each component, confirming the method’s capability to resolve polymers in complex samples.

Benefits and Practical Applications

Automated pyrolysis GC-MS provides high sensitivity (effective split up to 10000:1) and specificity for polymer identification. This approach is suited to microplastic monitoring in environmental matrices, quality assurance in polymer manufacturing, and forensic trace analysis.

Future Trends and Applications

Ongoing development of microplastic filtration and sampling devices will enable routine environmental monitoring. Integration with advanced data libraries and chemometric tools can further improve identification of novel or degraded polymers. Collaboration between instrument developers and environmental researchers will expand applications to fields such as marine biology, waste management, and regulatory compliance.

Conclusion

Automated pyrolysis GC-MS with the GERSTEL pyrolysis module offers a robust, sensitive, and rapid method for polymer characterization, capable of distinguishing individual and mixed plastics at trace levels. Its implementation can advance microplastic research and support industrial QA/QC processes.

Reference

Tsuge S, Ohtani H, Watanabe C. Pyrolysis-GC-MS Data Book of Synthetic Polymers: Pyrograms, Thermograms and MS of Pyrolyzates. 2011.