Py-GC/MS/MS Microplastic Analysis of Samples Containing Interfering Substances

Importance of the Topic

Microplastics are pervasive environmental contaminants that pose risks to ecosystems and human health. Their small size and complex sample matrices challenge conventional analytical methods. Pyrolysis gas chromatography with tandem mass spectrometry in multiple reaction monitoring mode offers enhanced sensitivity and selectivity for tracing diverse plastic polymers at low levels.

Study Objectives and Overview

This work applies Py GC MS MS with MRM to a mixed reference material containing 11 polymer types and to sea salt samples with matrix interferents. It compares Scan and MRM acquisition modes to assess improvements in calibration linearity, signal to noise performance, and quantitative accuracy in complex matrices.

Methodology

Calibration standards were prepared by diluting 11 microplastics in deactivated silica and weighing 0.05 to 1.0 mg into pyrolysis cups. Sea salt samples (100 g) were dissolved, filtered on 20 μm metal filters, folded into cups, and pyrolyzed. The pyrolyzer operated at 600 °C, transferring decomposition products through a 320 °C GC inlet and cryo focusing before chromatographic separation.

Instrumentation Used

• Frontier Lab Py-3030D pyrolyzer
• Agilent 8890 gas chromatograph with split injection and UA-5 capillary column
• Microjet cryo trap cooled by liquid nitrogen
• Agilent 7000E triple quadrupole mass spectrometer in electron ionization mode

Main Results and Discussion

Calibration curves in both Scan and MRM modes achieved R2 above 0.99 for most polymers over a range from several hundred nanograms to micrograms. MRM mode reduced baseline noise by factors of two to tens and improved S/N ratios compared to Scan. In real sea salt samples, Scan mode overestimated polymer levels due to coeluting matrix compounds, whereas MRM minimized interferences and enabled accurate quantification, as shown by chromatogram comparisons.

Benefits and Practical Applications

• Simultaneous quantification of multiple microplastic types with high throughput
• Superior sensitivity and selectivity in complex environmental and food matrices
• Robust calibration enabling trace-level detection for QA QC and research

Future Trends and Opportunities

Future developments may include automated sample preparation workflows, application to nano plastics and fibers, coupling with multidimensional chromatography, and use of machine learning for deconvolution of complex spectra. Standardized methods and certified reference materials will support routine environmental and safety monitoring.

Conclusion

Py GC MS MS in MRM mode is a powerful approach for quantitative analysis of mixed microplastics in challenging matrices. The method delivers excellent linearity, reduced matrix effects, and enhanced signal to noise, making it well suited for trace-level determination in environmental and food safety applications.

References

• Whitecavage J, Stuff JR, Vernarelli L Determination of Microplastics using Pyrolysis GC MS GERSTEL Application Note 212 2020
• Dierkes G et al Quantification of Microplastics in Environmental Samples using Pyrolysis and GC MSD Agilent Application Note 5994-2199EN 2020
• Braun U et al Accelerated Determination of Microplastics using Thermal Extraction Desorption GC MS Agilent Application Note 5994-2551EN 2020
• Yu HW et al Analytical methods for microplastics in freshwater Journal of Environmental Analysis Health Toxicology 23 2020
• Jones N et al Analysis of Microplastics using Pyrolysis GC xGC TOFMS Chromatography Today 2021
• Coralli I et al Secondary reactions in microplastics analysis by pyrolysis Journal of Analytical and Applied Pyrolysis 161 2022
• Pe nalver R et al Extractable pollutants from microplastics in vegetables Chemosphere 341 2023
• Harata K et al Identification of polymer species by pyrolysis GC APCI HRTOF MS Journal of Analytical and Applied Pyrolysis 148 2020
• Matsueda M et al Preparation of a reference mixture for microplastics analysis by pyrolysis GC MS Journal of Analytical and Applied Pyrolysis 154 2021
• Ishimura T et al Analysis of microplastics with calcium carbonate by pyrolysis GC MS Journal of Analytical and Applied Pyrolysis 157 2021
• ASTM International Standard Test Method D8401 2024
• Belz S et al Analytical methods to measure microplastics in drinking water EU JRC Publications Repository JRC136859 2024