Issues in the Analysis of Microplastics

Significance of the Topic

In recent years, the accumulation of microplastics in marine environments has raised concerns over ecological impact and human health. Accurate identification of microplastics is essential for assessing pollution sources and guiding mitigation strategies.

Objectives and Study Overview

This work evaluates the challenges of conventional FTIR libraries in identifying degraded plastics and demonstrates the effectiveness of specialized UV- and thermal-damage spectral libraries. Through three representative examples, the study highlights improved identification of weathered microplastics using advanced reference spectra.

Methodology and Instrumentation

Beach-collected white and blue microplastic fragments and irradiated polymer standards were analyzed using Fourier Transform Infrared spectroscopy with microscopic ATR for particle sizes down to tens of micrometers. To overcome mismatches with standard libraries, two dedicated spectral libraries were applied for plastics degraded by UV exposure and thermal heating.
Key instrumentation used:

• IRSpirit FTIR spectrophotometer
• QATR-S single-reflection ATR attachment
• Infrared Microscope AIM-9000
• IRTracer™-100 FTIR spectrophotometer

Main Results and Discussion

Example 1: White polypropylene shards from seashore samples, when compared with the UV-Damaged Plastics Library, matched UV-degraded polypropylene and eliminated false positives from standard libraries.
Example 2: Progressive UV irradiation of polypropylene produced characteristic O–H and C=O absorption bands, illustrating molecular cleavage and crosslinking that are absent in unaged spectra.
Example 3: Microscopic ATR analysis of blue microplastics from Arctic cod identified polymethyl methacrylate (PMMA) as the main polymer and detected kaolin (aluminum silicate) as an additive.

Benefits and Practical Applications

Implementing specialized UV and thermal damage libraries significantly enhances the reliability of qualitative microplastic analysis. This approach supports environmental monitoring, quality control in recycling processes, and forensic investigations of polymer degradation.

Future Trends and Opportunities

Expanding spectral libraries to cover additional polymer types and degradation conditions will further improve identification capabilities. Integration of automated search algorithms and machine learning may enable high-throughput, real-time screening of environmental microplastic samples.

Conclusion

Combining FTIR-ATR microscopy with UV- and thermal-damage spectral libraries offers a robust solution for identifying degraded microplastics. This methodology addresses the limitations of standard libraries and provides a practical framework for diverse environmental and industrial applications.