A critical comparison of the main characterization techniques for microplastics identification in an accelerated aging laboratory experiment

Many studies have reported the occurrence of microplastics in different environmental compartments, through the description of their morphological characteristics and chemical identification, obtained mainly by spectroscopic techniques. However, the scientific community still lacks the implementation of standardized analytical methods that aim to assess not only the identification of the particle, but also its stage of degradation. It is understood that this information would be extremely useful in helping elucidate the main sources of pollution and contributing to strategies and mitigating measures for the management of solid waste and microplastics in the environment. In this respect, the aim of this study was to evaluate the efficiency of Fourier-transform infrared spectroscopy, Raman spectroscopy, carbon elemental analysis coupled with mass spectrometry, and scanning electron microscopy with energy dispersive X-ray spectrometry for the characterization of virgin and aged polyethylene and polypropylene microplastics samples. The degraded samples were subjected to accelerated aging in a QUV chamber in accordance with American standard for measuring accelerated weather testing (ASTM G-154). This work discusses the efficiency and limitations of each technique for the detailed chemical characterization of microplastic samples collected from the environment.