Analysis of Microplastics Using AIMsight Infrared Microscope

Significance of the Topic

Microplastic pollution is a critical environmental issue affecting aquatic ecosystems globally. Precise identification of polymer types and particle size of microplastics is essential for source tracking and risk assessment.

Objectives and Study Overview

This study demonstrates the use of an infrared microscope to analyze microplastics collected on a PTFE filter. It aims to identify polymer compositions, map their spatial distribution, and measure particle dimensions.

Methodology and Instrumentation

Samples of microplastics were gathered from water using PTFE filter paper and analyzed by infrared transmission mapping. Key measurement parameters included a spectral resolution of 8 cm-1, 10 scans accumulation, square triangle apodization, and a 30 µm by 30 µm aperture with 30 µm mapping intervals over a 1560 µm by 1110 µm area.

• AIMsight infrared microscope
• IRTracer-100 spectrometer
• 15x reflective objective lens and wide-field camera
• AMsolution control software with length measurement function

Main Results and Discussion

Infrared spectra obtained from mapped pixels matched UV-damaged polyethylene (PE) and polypropylene (PP) reference libraries. Chemical imaging based on characteristic CH2 rocking at 718 cm-1 for PE and CH3 bending at 1373 cm-1 for PP revealed the spatial distribution of these polymers on the filter. Red regions indicated higher concentrations of the respective plastic components.

Benefits and Practical Applications

The technique enables accurate qualitative identification and spatial mapping of microplastic types directly on filter substrates. The integrated size measurement tool allows simultaneous dimension analysis, supporting environmental monitoring, quality control, and research workflows.

Future Trends and Potential Applications

Advances may include combining infrared and Raman microscopy for improved sensitivity on submicrometer particles, automation through machine learning for rapid classification, expansion of polymer libraries for degraded materials, and portable systems for field analysis.

Conclusion

The AIMsight infrared microscope provides high sensitivity and spatial resolution for mapping and characterizing microplastic pollutants. Coupled with a dedicated software suite, it delivers comprehensive material identification and particle size data, enhancing environmental analysis capabilities.

Reference

Shimadzu Corporation Application News No. 01-00454-EN, First Edition Feb 2023.