Analysis of Microplastics by iSpect™ DIA-10 Dynamic Particle Image Analysis System and AIM-9000 Infrared Microscope

Significance of the Topic

Microplastics pose a growing threat to marine ecosystems and human health. Their tiny dimensions and persistence in water bodies require reliable analytical techniques for rapid detection, quantification and chemical identification. Early and accurate assessment supports pollution source tracking and informs remediation strategies.

Study Objectives and Overview

This work demonstrates a hybrid analytical workflow combining dynamic particle image analysis and infrared microscopy. It aims to (1) characterize the size, shape and concentration of microplastic particles in environmental water samples and (2) perform qualitative identification of particle composition on filter substrates.

Methodology and Used Instrumentation

Samples of coastal water containing microplastic debris were processed by two complementary systems:

• iSpect™ DIA-10 Dynamic Particle Image Analysis System: Employs a microcell flow‐through imaging method, capturing 5–100 µm particles in real time from a 150 µL aliquot at 0.1 mL/min. Frame rate 8 fps.
• AIM-9000 Infrared Microscope coupled with IRTracer™-100 FTIR: Performs mapping and point analysis on PTFE‐trapped particles. Aperture 20×20 µm, spectral resolution 8 cm⁻¹, 5 scans, using an MCT detector over a 460 µm × 1 780 µm area.

Main Results and Discussion

Dynamic imaging captured over 5 300 particles per milliliter, with an average size of 24.3 µm. Scattergrams and histograms revealed that the highest frequency of particles fell in the 10–30 µm size range, with varied morphologies including rod‐like and fibrous forms. Infrared mapping of visually selected particles confirmed polypropylene (PP) by the characteristic CH₃ bending vibration at 1 400–1 339 cm⁻¹. Chemical imaging highlighted the spatial distribution of PP within individual fragments.

Benefits and Practical Applications

• High‐throughput shape and size profiling reduces operator burden compared to manual microscopy.
• Low sample volume requirement facilitates analysis of precious environmental or biological specimens.
• Infrared mapping delivers precise polymer identification and spatial composition data.
• Combined workflow supports environmental monitoring, regulatory compliance and research into microplastic transport and fate.

Future Trends and Possibilities

Advancements may include integration of Raman spectroscopy for non‐destructive chemical profiling, AI‐driven image classification for polymer type recognition, and miniaturized field‐deployable instruments for on‐site monitoring. Enhanced software analytics will enable automated reporting and cross‐study data comparison.

Conclusion

The hybrid use of dynamic particle image analysis and infrared microscopy provides an efficient, reliable approach for comprehensive microplastic evaluation in water samples. This method yields quantitative metrics on particle concentration, size and shape, combined with qualitative identification of polymer composition, supporting environmental assessment and mitigation efforts.

References

Associate Professor Yutaka Kameda, Chiba Institute of Technology, for provision of environmental samples and microplastics expertise.