Sample Preparation Method and FTIR Analysis Method for Microplastics Sampled from Rivers

Importance of the Topic

Microplastics are particles smaller than 5 mm that contaminate aquatic environments globally. Monitoring their distribution and degradation state is vital for assessing environmental impact and guiding remediation strategies.

Objectives and Study Overview

This study presents a workflow for sampling microplastics from river waters using the Albatross device and characterizing their degradation via FTIR spectroscopy. It aims to standardize sample preparation and demonstrate the use of Shimadzu's FTIR-based Plastic Analyzer for rapid analysis.

Methodology and Instrumentation Used

• Sampling: Albatross microplastic sampler submerged for 3 minutes in Kyoto Prefecture rivers.
• Sample preparation:
  1. Sieving through 2 mm and 0.1 mm meshes.
  2. Digestion of organic contaminants with 30% H2O2 at 60 °C for 3 days.
  3. Washing and density separation using 5.3 M NaI, standing for 7 hours to isolate microplastics.
• Instrumentation:
  • Shimadzu IRSpirit FTIR spectrophotometer.
  • QATR-S diamond ATR accessory.
  • Plastic Analyzer system with UV-damaged plastics library.
• Measurement conditions: resolution 4 cm-1, 45 scans, 4000–600 cm-1 range, DLATGS detector, SqrTriangle apodization.

Main Results and Discussion

FTIR spectra revealed key features of oxidative degradation: O-H stretching near 3400 cm-1 and C=O stretching near 1750 cm-1, matching polyethylene after 550 hours of UV irradiation. A peak around 1050 cm-1 indicates possible silicate contamination from environmental particulates.

Benefits and Practical Applications

• The workflow uses readily available equipment and standardized reagents for reproducible results.
• Plastic Analyzer simplifies degradation assessment without requiring expert interpretation.
• Applicable for routine environmental monitoring and quality control in research and industry.

Future Trends and Possibilities

Anticipated developments include expanding reference libraries for broader polymer types, integrating automated sample handling, and deploying portable FTIR systems for in situ analysis. Combining spectroscopy with imaging techniques may further enhance microplastic characterization.

Conclusion

The combined sampling preparation and FTIR analysis workflow enables efficient detection and degradation profiling of riverine microplastics. Shimadzu's Plastic Analyzer system provides a robust tool for environmental investigations.

Reference

R. Fuji, Sample Preparation Method and FTIR Analysis for Microplastics Sampled from Rivers, Shimadzu Application News, First Edition February 2021.