Pyrolysis-GC-Orbitrap MS - A Powerful Analytical Tool for Identification and Quantification of Microplastics in a Biological Matrix

Importance of the Topic

The pervasive release of microplastics into the environment poses health and ecological risks. Reliable identification and quantification of microplastic polymers in complex biological samples are essential for monitoring pollution, assessing exposure, and guiding remediation strategies.

Objectives and Study Overview

This work evaluates the performance of pyrolysis gas chromatography coupled with high-resolution Orbitrap mass spectrometry for both qualitative and quantitative detection of microplastics. Key aims include demonstrating sensitivity, linearity, selectivity, and the added value of non-targeted analysis in a biological matrix.

Methodology and Instrumentation

Samples were introduced via single-shot pyrolysis (600 °C) using a vertical micro-furnace pyrolyzer. Evolved pyrolysis fragments were separated on a Thermo Scientific TRACE™ 1310 GC with a 30 m × 0.25 mm column under a 40–320 °C temperature program (20 °C/min). Detection employed a Q Exactive™ GC Orbitrap™ GC-MS/MS in full-scan and SIM modes at up to 60 000 resolving power, enabling accurate mass measurement in the 30–3000 m/z range.

Used Instrumentation

• Frontier Lab EGA/PY-3030D Multi-Shot Pyrolyzer
• Thermo Scientific TRACE™ 1310 Gas Chromatograph
• Thermo Scientific Q Exactive™ GC Orbitrap™ GC-MS/MS System
• Chromeleon™ CDS and TraceFinder™ Software for data acquisition and analysis

Main Results and Discussion

Calibration with polystyrene (PS) and polymethyl methacrylate (PMMA) standards (0.05–50 µg) yielded excellent linearity (R² > 0.999) and sub-ppm mass accuracy. In fishmeal spiked with PS and PMMA, quantification remained accurate across concentrations. High resolution (60 000) allowed selective extraction of target ions within ±5 ppm, effectively resolving co-eluting pyrolysis products in polymer mixtures. Non-targeted screening identified additional degradation markers, e.g., α-methylstyrene from PS.

Benefits and Practical Applications

• High sensitivity and broad dynamic range for trace microplastic quantification.
• Sub-ppm mass accuracy ensures confident polymer identification in complex matrices.
• Non-targeted full-scan capability enables discovery of unknown degradation products.
• Robust performance supports environmental monitoring, food safety, and regulatory compliance.

Future Trends and Potential Applications

Advances may include integration of automated sample preparation, expanded spectral libraries for polymer derivatives, miniaturized portable pyrolysis-GC-Orbitrap systems for in-field analysis, and AI-driven data interpretation to enhance throughput and reproducibility.

Conclusion

Pyrolysis-GC coupled with Orbitrap high-resolution mass spectrometry offers a powerful platform for comprehensive microplastic analysis in biological samples. Its combination of quantitative accuracy, selectivity, and non-targeted detection positions it as a valuable tool for research and routine monitoring of plastic pollution.

Reference

• Jambeck JR et al. 2015. Plastic waste inputs from land into the ocean. Science Reports.