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Updated: Oct 25, 2025
Protocol for Microplastics Sampling on the Sea Surface and Sample Analysis
Published on: December 16, 2016
Reevaluation of microplastics identification based on Neuston net survey data
Haruka Nakano1, Keiichi Uchida2, Tetsutaro Aikawa2
1Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato-ku, Tokyo 108-8477, Japan; Environmental Management Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba 395-8569, Japan.
Fourier transform infrared spectroscopy (FTIR) analysis improves microplastic (MP) data accuracy by removing non-MP fragments, particularly smaller ones. This refinement is crucial for accurate MP size distribution analysis, especially for fragments versus foam.
Area of Science:
- Environmental Science
- Analytical Chemistry
- Materials Science
Background:
- Accurate quantification of microplastics (MPs) is essential for environmental monitoring.
- Visual identification methods can lead to overestimation of MP concentrations due to impurities.
- Fourier transform infrared spectroscopy (FTIR) offers advanced optical identification capabilities.
Purpose of the Study:
- To assess the impact of chemical preprocessing and FTIR analysis on microplastic data accuracy.
- To identify the causes of MP number concentration overestimation without FTIR.
- To differentiate the effects of FTIR on various MP shapes, specifically fragments and foam.
Main Methods:
- Survey data analysis of microplastic samples before and after FTIR identification.
- Comparison of microplastic counts, shape types (fragments, foam), and size distributions.
- Focus on the influence of FTIR on visually identified fragments and foam.
Main Results:
- FTIR analysis significantly reduced the proportion of identified fragments, while foam proportion increased.
- A significant difference in size distribution was observed for fragments post-FTIR (> before FTIR).
- No significant difference in size distribution was found for foam before and after FTIR.
Conclusions:
- Impurities, particularly fragments <1000 μm, are often misidentified and removed by FTIR.
- The recommended size threshold (>1000 μm) for microplastic analysis should be applied cautiously.
- This threshold is appropriate for fragments but not for foam, highlighting the need for shape-specific analysis.
