The rising concerns about marine life and human exposure to microplastics have increased the interest in evaluating the synthetic polymers abundance in the environment. Chemical analysis using spectroscopy is necessary to classify microscopic debris as of man-made or natural origin. However, analysis and classification of microfibers are particularly challenging using conventional FT-IR and spontaneous Raman microscopy due to the small dimensions of the specimens (diameter smaller than 15 micrometers) and the strong autofluorescence present in some samples. Stimulated Raman scattering (SRS) microscopy allows to perform measurements on conventional glass substrates and is not affected by sample autofluorescence, overcomes the limitations of micro-FT-IR analysis, and allows to sensibly speed up the chemical characterization of environmental microfibers. Utilizing a custom SRS microscopy system, we built a library of SRS spectra of the natural and synthetic polymers that constitute the most abundant microfibers in the environment. SRS analysis and a comparison with the spectra in the library allowed us to characterize the origin of microfibers found in different environments. The majority of the microfibers analysed are of natural origin, in accord with other studies that used spectroscopy to assess the specimens’ chemical composition. This result highlights the importance of using spectroscopy to evaluate the man-made or natural origin of microfibers, and potentially implies that previous studies could have over-estimated the abundance of synthetic materials in the environment.

Presenter: Luca Genchi, King Abdullah Univ. of Science and Technology (Saudi Arabia)

Author(s): Luca Genchi, King Abdullah Univ. of Science and Technology (Saudi Arabia); Sergey Laptenok, King Abdullah Univ. of Science and Technology (Saudi Arabia); Cecilia Martin, King Abdullah Univ. of Science and Technology (Saudi Arabia); Fadiyah M. Baalkhuyur, King Abdullah Univ. of Science and Technology (Saudi Arabia); Carlos M. Duarte, King Abdullah Univ. of Science and Technology (Saudi Arabia); Carlo Liberale, King Abdullah Univ. of Science and Technology (Saudi Arabia) 

Source Name: SPIE, Paper PC12136-82

Source URL: https://spie.org/photonics-europe/presentation/Classification-of-environmental-microfibers-using-stimulated-Raman-microspectroscopy/PC12136-82