Chemical Analysis of Polymer Microbeads in Toothpaste by TD- and Py-GC×GC-TOFMS

Significance of the Topic

The use of plastic microbeads in personal care products presents environmental and health concerns. Characterizing these microbeads in consumer items such as toothpaste is crucial for understanding their chemical composition and potential impact.

Objectives and Overview of the Study

This study applies consecutive thermal desorption and pyrolysis techniques coupled with GC×GC-TOFMS to profile both volatile additives and polymer microbeads in a commercial toothpaste.

Methodology

About 20 mg of toothpaste was analyzed by thermal desorption at 50–250 °C followed by flash pyrolysis at 750 °C using a CDS Pyroprobe 5200, with evolved compounds separated on a dual-column GC×GC system and detected by a Pegasus 4D TOFMS.

Used Instrumentation

• Agilent 7890 GC equipped with Rxi-5ms (30 m × 0.25 mm, 0.25 µm) and Rxi-17SilMS (1.25 m × 0.18 mm, 0.18 µm) columns
• CDS Pyroprobe 5200 for controlled thermal desorption and pyrolysis
• LECO Pegasus 4D TOFMS with open, low-maintenance ion source

Main Results and Discussion

Thermal desorption identified menthol, wintergreen oil, glycerin, propylene glycol, PEG-6 oligomers, saccharin derivatives, and various fatty acids. Pyrolysis revealed characteristic polyethylene fragments (dienes, alkenes, alkanes) with library match scores above 900. Two-dimensional separation effectively resolved polymer profiles from complex matrices.

Contributions and Practical Applications

The combined TD-GC×GC-TOFMS and Py-GC×GC-TOFMS workflow enables comprehensive profiling of both small molecule additives and non-volatile polymers in complex formulations, supporting regulatory compliance and product safety assessment.

Future Trends and Applications

Advances in GC×GC modulation, high-resolution TOFMS, expanded spectral libraries, and machine learning deconvolution are expected to enhance sensitivity, throughput, and automation in microplastic analysis across diverse sample types.

Conclusion

The dual thermal separation approach on the Pegasus 4D platform offers detailed chemical insight into toothpaste formulations. Its high peak capacity and robust ion source deliver an efficient solution for research, quality control, and environmental monitoring of polymer microbeads.